Group 11
Final Report
April, 2005
Table of Contents
Table of Contents ................................................................................................................... 1
List of Figures ......................................................................................................................... 3
List of Tables ........................................................................................................................... 3
Project Overview .................................................................................................................... 4
Design Problem .................................................................................................................. 4
System Overview ............................................................................................................... 4
Division of Tasks ................................................................................................................ 5
Smart Sensor System Design .............................................................................................. 6
Introduction.......................................................................................................................... 6
Wind Speed ......................................................................................................................... 7
Wind Direction..................................................................................................................... 8
System Microcontroller ........................................................................................................ 10
Selection ............................................................................................................................ 10
Features ............................................................................................................................. 10
Processing Software ............................................................................................................ 11
Overview ............................................................................................................................ 11
Power-up and Initialization.............................................................................................. 11
Configuration ..................................................................................................................... 12
Sampling ............................................................................................................................ 13
Output Data ....................................................................................................................... 14
Output Hardware .................................................................................................................. 16
RS-232 ............................................................................................................................... 16
RS-485 ............................................................................................................................... 17
RC1090 .............................................................................................................................. 18
Output Software.................................................................................................................... 20
RC1090 Configuration ..................................................................................................... 20
PCB ........................................................................................................................................ 23
The Design of the Printed Circuit Board ....................................................................... 23
Designing Footprints ........................................................................................................ 23
Board Dimensions ............................................................................................................ 23
Placement of the Components ....................................................................................... 24
Routing the Traces ........................................................................................................... 25
Manufacturing of the PCB ............................................................................................... 26
Wireless Transceiver PCB .............................................................................................. 26
Troubleshooting ................................................................................................................ 27
Recommendations ........................................................................................................... 27
References ........................................................................................................................ 27
Appendices............................................................................................................................ 28
Appendix A Schematic .................................................................................................... 28
Appendix B - PCB ............................................................................................................ 29
Appendix C - Data Sheets .............................................................................................. 30
Appendix D - Bill of Materials ......................................................................................... 31
Appendix E – Source Code ............................................................................................ 32
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List of Figures
Figure 1. Overall System Block Diagram
Figure 2. Detailed layout of the RM Young 05103[1]
Figure 3. Wind speed circuit implementation
Figure 4. Wind direction circuit implementation with dead band compensation
Figure 5. ICL3221 External Circuitry and Interface[3]
Figure 6. ISL83485 External Circuitry and Interface
Figure 7. Connection to host MCU or RS232/422/485 drivers
Figure 8. footprint layout of ICL3221
Figure 9. PCB Dimensions
Figure 10. Fixed Location Parts
Figure 11. PCB layout of top side
Figure 12. PCB layout of bottom side
Figure 13. PCB being etched at Camosun College
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List of Tables
Table 1. Project Tasks ............................................................................................................... 5
Table 2 Required Capacitor Values[2] .................................................................................. 16
Table 3. Basic Parameters ....................................................................................................... 19
Table 4. List of Configuration data for the smart sensor ........................................................ 21
Table 5. Procedures for Configuration.................................................................................... 22
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Project Overview
Design Problem
A portion of this design problem hinges on some research that needs to be
completed on the RM Young 05103 wind sensor. This research will determine
whether or not the wind sensor will be able to charge a battery when not
acquisitioning data. If the charging power proves to be adequate then a transceiver
will be added (PartB) to the initial design to provide a completely wireless sensor.
The initial design problem (PartA), which is to create a smart sensor is detailed as
follows:



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Operating input voltage is to be between 5 and 17 volts.
The operating current will be less than 10mA.
Package size is to fit within 2”x1”x1.2” area.
Minimum input sampling rate is to be 10 Hz.
Unprocessed data output is selectable from 1 to 10 Hz.
Processed data output is selectable with averaging interval, averaging
duration and data rate.
Serial data rate is selectable from 1200 to 115kB/s.
The target cost per unit is less than $25/unit.
System Overview
A PIC 16F88 microcontroller will be used for the overall control of:
 Hardware interface
 translating of aquisitioned data
 serial i/o to hardwired and wireless transceivers
The aquisitioned data will come from the RM Young 05103 wind sensor, which
produces both wind speed and direction. The serial i/o can be set via a jumper to
choose either a hardwired connection or a wireless connection. This serial link will
enable the user to select different output rates and protocols for transmission.
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Division of Tasks
Table 1. Project Tasks
Shawn
Derek
Robert
Jonathan
Part Research
RS232
RS485
Transceiver
Microcontroller
Wind Sensor
Hardware Design
Wind Sensor Interface
Serial Interface
Transceiver Interface
Schematic Design
Smart Sensor
Transceiver
Hardware Testing
PCB Design
Smart Sensor
Transceiver
PCB Implementation
Smart Sensor
Transceiver
Software Design
Sampling Functions
Control Functions
Data Processing
Software Testing
Documentation
Progress Report#1
Progress Report#2
Final Report
Poster Design
Website Design
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Smart Sensor System Design
Introduction
The entire system is based around a PIC16f88 from Microchip which aquires data from the
wind sensor. Wind speed is measured via counting the rising edge of a square wave. This
signal is originally a generated AC waveform from the sensor that has been conditioned
through the use of an opamp. The WindSensor has a internal potentiometer that outputs a
varying voltage depending on its position. This voltage is applied to the PICs A/D converter
and the corresponding wind direction is determined.
Communication is achievable via three ways.
 RS-232
 RS-485
 Wireless
Each mode is controlled via an enable, which allows each device to be shutdown when not
being used. The overall circuit schematic is seen in Appendix A. A block diagram of the
circuit is seen in figure 1 below.
Figure 1. Overall System Block Diagram
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Wind Sensor
To acquire the wind characteristics an RM Young Model 05103 wind sensor was
chosen. A detailed layout of the RM Young 05103 is shown in Figure 2. This wind
sensor is a high performance wind monitor that measures and records horizontal
wind speed and wind direction. It contains four blades that produces an AC sine
wave voltage signal with frequency directly proportional to wind speed. The wind
sensor
It also operates over a wide temperature range and is protected from high voltage
transients.
Figure 2. Detailed layout of the RM Young 05103[1]
Wind Speed
The propeller rotation of the RM Young 05103 produces an AC sine wave signal with
frequency proportional to wind speed. This AC signal is induced in a stationary coil
by a six-pole magnet mounted on the propeller shaft. Three complete sine wave
cycles are produced for each propeller revolution. Conditioning of this AC signal
must be done to produce a signal that can be easily converted to a digital signal.
The generated AC sine wave is fed into the input of an operational amplifier(fig 2.) to
produce a square wave with the same period and therefore still proportional to the
wind speed. The period of the square wave can be calculated from the onboard
asynchronous timer of the processor (PIC16F88). The period is measured from the
number clock pulses of the oscillator between two consecutively rising edges of the
square wave. The number of clock pulses and the frequency of the oscillator are
Pg.
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used to calculate the precise wind speed. The wind speed can be determined from
the following formulas.
Figure 3. Wind speed circuit implementation
WIND SPEED vs PROPELLER RPM
m/s = 0.00490 x rpm
knots = 0.00952 x rpm
mph = 0.01096 x rpm
km/h = 0.01764 x rpm
WIND SPEED vs OUTPUT FREQUENCY
m/s = 0.0980 x Hz
knots = 0.1904 x Hz
mph = 0.2192 x Hz
km/h = 0.3528 x Hz
Wind Direction
The RM Young 05103 transmits the wind direction by a 10k
plastic potentiometer, which requires a regulated excitation voltage of 3.3 volts. With
a constant voltage applied to the potentiometer, the output signal is an analog
voltage directly proportional to wind direction angle. It is important to note that, while
the sensor mechanically rotates through 360°, the full scale electrical signal only
rotates through 355°. Therefore external signal conditioning electronics must be
placed accordingly. When the potentiometer wiper is in the 5° deadband region, the
output signal is floating and may show varying or unpredictable values. To prevent
these false readings, the potentiometer was placed across an operational amplifier
as a feedback resistor. One side of the pot was connected to output of the op-amp
and the wiper was connected to the negative input of the op-amp. As the
potentiometer enters the deadband region, then the op-amp goes open-loop and the
output voltage goes to the railing voltage (3.3V). The output voltage is then fed into
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another op-amp with negative unity gain to invert the voltage to a positive signal.
The signal conditioning electronics are shown in Figure 4. The analog voltage
corresponding to the wind direction now varies between 0V and 3.3V without a
deadband. This analog voltage is converted into digital data using the 10 bit analogto-digital converter (ADC) of the processor.
Figure 4. Wind direction circuit implementation with dead band compensation
WIND DIRECTION vs VOLTAGE
0° = 0V
355° = 3.3V x (355°/360°) = 3.25417
360° = 3.3V
WIND DIRECTION vs VOLTAGE
0° = 0V
355° = 1.65V x (355°/360°) = 1.62708
360° = 1.65V
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System Microcontroller
Selection
During research for which type of microcontroller to use for the project, the PIC16F88
presented itself with many of the features required; low power, small in size, asynchronous
timer - to name a few. The 16F88 belongs to the ‘Mid-Range’ level microcontroller family
manufactured by Microchip Technology Inc and is widely available and relatively low
priced. Because the project sponsor had specified a preference for PIC microcontrollers, the
decision to choose the 16F88 as the processing core of the project was an easy one.
Features
The microcontroller, being at the heart of the data acquisition system, has to perform several
different tasks. It has to acquire two separate forms of data; a linear voltage scale for
direction and a linear frequency scale for speed. It also has to transmit its data, accept
incoming configuration data, and all the while limit the power consumption of itself and the
rest of the circuit.
Due to the fact that it was uncertain how much power the BSS project group could provide,
the overriding requirement of the sensor design was that it be low power. Indeed, low power
operation is always a responsible goal, but in this situation it was a key element. The PIC
16F88 is among a group of Microchip microcontrollers which sell under the ‘nano-Watt
Technology’ badge. Integral to the PIC’s miserly power consumption is its ability to enter
‘sleep’ mode. In this mode, the oscillator driver is turned off and under ideal conditions the
PIC will draw around 100 nA. The 16F88 provides several options to prompt a wake up
from sleep, but in order to provide a configurable periodic sleep cycle, this particular PIC has
a separate prescaler for its watchdog timer, ideal for handling the sample rate range specified
by the sponsor.
In order to read the linearly changing voltage scale (representing direction) provided by the
op-amp circuitry, the PIC 16F88 has an onboard 10-bit Analog to Digital converter (A/D).
The PIC is quite generous with the number of analog pin configurations available, however
only one active input is required for the conversion (Port A bit 0) with two other pins
providing reference levels to the maximum voltage, Vref+ (Port A bit 3), and minimum
voltage, Vref- (Port A bit 2). The ten bit A/D provides a resolution on the 360 degree scale
of 360 / 210  0.3515625 per bit which is acceptable for the given application.
The data acquisition circuitry provides a square-wave with a frequency directly proportional
to the wind speed at the sensor. This presented a unique requirement for the microcontroller.
In order to accurately measure speed, it would need to be able to count every cycle of the
square wave, even though power consumption dictated that it must be ‘asleep’ for the vast
majority of its operational life. The 16F88 has three onboard timers, but it is Timer1 alone
that fills the niche of this particular challenge. One of the modes this timer can operate in is
that of an asynchronous counter. In this mode the timer continues to increment asynchronous
to the internal phase clocks and will continue to run during ‘sleep’ mode. By reading and
clearing Timer1 at regular intervals, an accurate measurement of speed can be obtained.
Pg. 10
To transmit and receive data, the PIC 16F88 has the choice of three serial standards; Serial
Peripheral Interface (SPI™), Inter-Integrated Circuit (I2C™), and an Addressable Universal
Synchronous Asynchronous Receiver Transmitter (AUSART). Contrary to the AUSART’s
complex epithet, it was the standard of choice due to its ease of integration and lack of
overhead. The PIC’s onboard baud rate generator is configurable over the entire
communication rate range specified by the sponsor. Receives from the AUSART can
generate an interrupt, freeing the processor from having to take time to ‘listen’ for incoming
configuration data. Transmissions simply require a byte sized write to the TXREG and the
AUSART will begin transmitting.
Even though the PIC 16F88 had all the features required for the problem specification, one
limiting factor made its presence felt near the end of development - program memory space.
The 16F88 has 4 kilo-words of program space which is a mid to high amount for its device
family, and seemed more than adequate upon initially sourcing the chip, but later proved to
make the processing and averaging of the data a challenge to squeeze in.
Processing Software
Overview
To utilize all the features offered by the PIC 16F88, Hi-Tech Software’s PIC-C compiler was
used as the language suite within Microchip’s MPLAB developer’s environment to create the
required software solution. Once compiled, the software produces a program for the
microcontroller which manages all facets of the sensor operation. The source code is
included within Appendix E. This section of the report will explain the operation of the
device and how the end user can operate it.
Power-up and Initialization
As with any embedded application, it is necessary to initialize certain registers within the
processor to ensure proper operation of the device after power-up. Within Main.C (refer to
Appendix E) the initialization steps are performed at the bit level for clarity. These
operations configure the direction of the I/O pins and whether they operate as digital or
analog I/O. Timer1 is configured for asynchronous counter mode and the watchdog timer
(WDT) is configured to run off its own prescaler. The only interrupt which gets enabled is
the AUSART receive interrupt flag (RCIF), and once the global and peripheral interrupt
enables are set, the device is ready to receive configuration data.
However, the device will not wait to receive a configuration before beginning operation. It
will either operate with the configuration it had preciously – if it has been configured already,
or it will operate in a default mode – if it has not. This is possible because the device’s
configuration is stored in the PIC’s Electrically Erasable Programmable Read Only Memory
(EEPROM). During initialization, the device will check the location of its configuration
bytes within the EEPROM. If there is valid data there, it will set it to its volatile
configuration bytes and operate as previously programmed.
Pg. 11
Configuration
As soon as the PIC has set its global and peripheral interrupt enables, the device is ready to
receive configuration data. If the device is operating in the default mode, this data will be
sent over RS232 communication at 19.2k BAUD, if not, the data can come over which ever
medium the sensor has been configured for.
As soon as a character is received in the receive register (RCREG) the PIC triggers an
interrupt which shuts off the WDT (preventing an unwanted reset during configuration) and
calls the dataReceive() function (refer to Functions2.C in Appendix E). This function is
written to look for a specific preamble (HEX ‘55’s or ASCII ‘U’s) before modifying the
device’s configuration. At anytime within this function, if the device receives an invalid
character, the PIC will leave the interrupt without modifying the configuration settings and
return to its previous operation prior to the interrupt. Below is a map on how to construct a
valid configuration string of ASCII characters for the device:
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Preamble:
o A continuous transmission of ‘U’s for a period greater than the devices sleep
cycle, such that it may catch the preamble and enter dataReceive().
First Character:
‘H’ or ‘W’ – not case sensitive
o Select ‘H’ if the device is to be hardwired via either the RS232 or RS485
communication chips, or select ‘W’ if it will be communicating wirelessly.
Second Character:
‘2’ or ‘4’
o Select ‘2’ if the device is to communicate via the RS232 chip, or select ‘4’ if it
is to use RS485 communication. If the device is set to Wireless, this choice is
not important, but a ‘2’ or ‘4’ must be entered to continue with configuration.
Next Four Characters: A four bit ‘ASCII Binary’ string from“0000” to “1111”
o These ones and zeroes will translate directly into the part of the configuration
dealing with communication rate. For example, entering the combination ‘1’
’0’ ’1’ ’1’ (equivalent to decimal 11) will set the device to communicate at
28.8k BAUD. Refer to the comSpeed() funtion within Funtions2.C in
Appendix E for the entire table of configurable speeds.
Seventh Character:
‘R’ or ‘P’ – not case sensitive
o Select ‘R’ if the desired output is a raw data string, or select ‘P’ if the output
must be a processed data string (Refer to Output Data within this section).
Next Four Characters: A four bit ‘ASCII Binary’ string from“0110” to “1011”
o This string defines the setting for the WDT prescaler which in turn determines
the sleep cycle period (and in effect, the sample rate). The combination ‘1’
‘0’ ‘0’ ‘0’ (decimal 8) will cause the sleep period to be 316ms. Refer to the
setWdtPs() funtion within Funtions2.C in Appendix E for the entire table of
configurable periods.
Twelfth Character: ‘m’ or ‘M’ or ‘K’ or ‘N’ – only the ‘m’ is case sensitive
o This character determines what unit the sensor will calculate speed with. ‘M’
for mph, ‘K’ for km/h, ‘N’ for knots, and ‘m’ for m/s.
Pg. 12
An example of a valid configuration string:
“.UU..<U’s over the length of the sleep cycle>..UUH21001R1010K”
This string would set the device to hardwired communication over RS232 at a rate of 19.2k
BAUD with raw data as the output, a sleep period (sample rate) of 1.12 seconds, and km/h as
the unit of speed measurement.
Once a valid string has been entered, the program translates the information onto the volatile
configuration bytes and then returns to the interrupt service routine (ISR). Before exiting the
ISR the WDT is re-enabled and an ‘updated’ flag is set which prompts the main program to
act upon the recent configuration data and save that setting to the EEPROM before entering
the next sleep cycle.
Sampling
When the device is not receiving data, it operates out of an infinite loop within Main.C.
There, it checks the updated flag and updates the PIC’s settings if required. It then enables
the appropriate communication chip and enables the sample circuit which provides reference
voltages for the direction detection circuit before calling the sample() function within Main.c.
The integral part of the sample() function is its data acquisition. It first performs an A/D read
(readADC() function) and acquires a ten bit value for the wind direction. It then performs a
fail safe read of the two Timer1 counter registers, TMR1H and TMR1L and combines the
two bytes into an integer which is then multiplied by the appropriate conversion constant to
obtain the correct speed, according to the device’s configuration. It then disables the sample
circuit before acting on the acquired data (refer to Output Data). After acting on the data and
transmitting its output string, the function returns to the main loop.
Once back in the main loop, the program makes sure all power consuming circuits are
disabled and then executes a sleep() function call to enter ‘sleep’ mode (refer to System
Microcontroller – Features). It remains in this low power shutdown mode for the remaining
time of the sleep cycle period which is governed by the WDT prescaler. At the end of that
period, the PIC ‘wakes up’ and performs a NOP to allow the program counter to pick up at
the next instruction which carries it to the top of the loop again. This essentially defines the
sleep period of the device as the sensor’s sample period.
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Output Data
There are two separate forms of output for the device, as specified by the sponsor. The first
is ‘raw’ data and the second is ‘processed’ data. Each has their own NULL terminated string
of characters based on the NMEA standards (see http://www.nmea.org for more information)
stored globally within Main.C. The raw data string is rawFeed[32], which is initialized at
"$WIMWV,ID,999.9,R,888.88,m,A*CS” and processed data is processedFeed[70], which is
initiallized to
“$AXMWV,ID,036,175.1,R,000.00,000.00,000.00,000.00,000.00,000.0,m,A*CS". Below is
a description of the NMEA elements within the strings:
•
rawFeed[32]:
$WIMWV,ID,175,R,000,N,A*20
ID
=
Unique Sensor ID
175
=
direction
R
–
for Relative Direction
000
=
speed
N
–
Knots (M – MPH, m – m/s, K – km/h)*
A
–
Alarm
CS
=
XOR Checksum
•
processedFeed[70]:
$AXMWV,ID,Dur,175,R,001,002,003,004,005,120,N,A*CS
ID
=
Unique Sensor ID
Dur =
Wind Average Duration
175
=
Average Vector direction
R
–
for Relative Direction
001
=
Average Scalar speed
002
=
Average Vector Speed
003
=
Gust Speed
004
=
Minimum Speed
005
=
Maximum Speed
120
=
Wind Variation
N
–
Knots (M – MPH, m – m/s, K – km/h)*
A
–
Alarm
CS
=
XOR Checksum
*modified MPH to ‘M’ from ‘S’ for clarity during the demonstration.
Within the sample() function, the PIC acts upon the data based on whether it is set for raw or
processed output. If the output is the raw data, the program simply passes the speed and
direction, individually, to a function which returns a pointer to the first element of a string
containing the ASCII representation of the passed data, and then updates the appropriate
elements of the rawData[] string. If instead the output data is set to processed, then a series
of operations are performed to find each value within the processedFeed[] string.
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
DUR, Wind Average Duration. This value is hard-coded into the device as 36
seconds due to the fact that in order to sample over a long enough period to detect
wind gusts, the device has to operate with the 1.12s sample period only.

175, Average Vector Direction. Over the Wind Average Duration, the PIC updates
two eight element circular buffers every 4.5 seconds with pre-averaged values for the
X and Y components of the wind’s vector speed - such that it can maintain moving
average values for each. To find the vector components of the wind speed and
direction, the values are passed to a function which converts the magnitude (speed)
and direction into its orthogonal X and Y components (see the getXY() function
within Functions.C in Appendix E). This happens every 1.12s with every sample.
The pre-averaging is done by summing the four X and Y components sampled over
the 4.5 seconds and then right shifting the data by 2 (divide by four). The moving
average is maintained in much the same way. The two averages for X and Y (sumX
and sumY within the sample() function) add their pre-averaged amounts, av_x and
av_y, after pre-averaging them again (right shifting by 3 for the eight elements) .
Then the current circular buffer element is subtracted from the moving average before
inserting the new pre-averaged value into that circular buffer slot. With the moving
average values, sumX and sumY, the Average Vector Direction can be found by
passing these values to an arctan lookup function, arcTan() within Functions.C. This
value is converted to a character string and the processedFeed[] string is updated.

001, Average Scalar Speed. The same eight element circular buffer technique used to
average the X and Y components is also used to maintain the scalar speed moving
average, sum_vel. The output string is updated with this value.

002, Average Vector Speed. This value is essentially the Pythagorean sum of the X
and Y components. However, since squaring integers and subsequently finding the
square root of their sum involves a lot of program memory overhead, the function
hypotenuse() was developed for this application. A brief description of its operation
is that it takes the largest value between X and Y and sets it as the base value. It then
states that the other is going to be some ratio of 0 -1 of the base. It finds that ratio and
determines the starting value for the hypotenuse from an eight position look up table.
However, it maintains accuracy between the look up points by adding a remainder
amount onto the starting value of the hypotenuse. The value from this function is
then converted to a characters and the output string is updated,

003, Gust Speed. To find this, the elements within the scalar speed circular buffer are
run through a max/min algorithm which finds both after one pass through the array.
If the max and min differ by a set value, then the max is selected as the gust strength.
This element requires another sort to ensure a gust is not reported after a long period
of high winds followed by a lull. However program memory space dictated that
should be looked at in a future revision.
Pg. 15


004, Min Speed and 005, Max Speed. With the max and min values found during the
Gust detection search, this operation simply involves a character conversion and
output string update.
120, Wind Variation. This operation is done by doing the same max/min algorithm
on the eight element circular buffer containing the instantaneous direction values
taken every 4.5 seconds then finding the difference between them. If the difference is
greater than 360 degrees, the output string is updated with 360 – the difference.
Otherwise the difference is reported.
Output Hardware
RS-232
The first protocol of serial communication considered was RS-232. For this the Intersil
ICL3221 device was chosen. This surface mount chip had many attractive features including
its low operating power (1uA @ 3-5.5V), size, capable data rate of 250Kbps, auto power
down and it meets the EIA/TIA-232/V.28/V.24 industry specifications. The supply current of
1uA is a result of Intersils efficient on-chip charge pumps along with the manual and
automatic power down functions. The automatic power down function powers down the onchip power-supply and driver circuits. This occurs whenever the attached device removes its
valid applied RS-232 voltage at the receiver input. For this design the chip is turned off and
on through a software enable. This was achieved by tying pin 13 of the PIC to pin 16
(!FORCEOFF) on the ICL3221 chip. To disable, a logic low is applied. To re-enable, a logic
high must be applied. A jumper header was also connected between these pins that could be
removed when the in circuit debugger was to be used. This allowed for one pin to have
multiple roles. For all the external circuitry please refer to the Intersil ICL3221 data sheet in
Appendix C. It is important to note that for proper operation of the charge pumps the
required capacitor values must match Vcc as seen below in Table 2. For this circuit we
choose values in the 4.5 to 5.5V Vcc range. See figure 5 for the ICL3221 circuit and
interface.
Table 2 Required Capacitor Values [2]
Pg. 16
Figure 5. ICL3221 External Circuitry and Interface [3]
RS-485
The implementation of the RS-485 serial communication protocol was achieved using a
Intersil ISL83485 surface mount device. The chip is a 3.3V, high speed, RS-485/RS-422
transceiver that meets both the RS-485 and RS-422 standards for balanced communication.
This half duplex device configures the RX input and Tx output with RX and Tx disable
functions. Data rates of up to 10Mbps are available. The devices logic inputs (pins DE and
DI) allow for accepted input signals beyond 5.5V making them compatible with the majority
of 5V logic families. Another attractive attribute of this chip is the “fail-safe if open” feature,
which establishes a logic high output whenever RX inputs are left floating. The Tx driver
outputs are also short circuit protected for any excessive power supply voltages. The
operating current for this device is .65mA and 15nA in low current shutdown mode.
Switching from operating mode to low current mode is achieved through the use of a mosfet
as seen in figure 6 on the following page. For all external circuitry refer to the Intersil
ISL83485 data sheets in Appendix C.
Pg. 17
Figure 6. ISL83485 External Circuitry and Interface
This mosfet allows both the !RE and DE pins on the ISL83485 to be configured using only
one pin on the PIC. The !RE pin is the receiver output enable. RO is enabled when !RE is
low; RO is high impedance when !RE is high. The DE pin is the driver output enable. The
driver outputs, Y and Z, are enabled by bringing DE high. They are high impedance when
DE is low.
RC1090
The RC1090 is a RF Transceiver Module produced by Radiocrafts. This compact, "all
included", standard transceiver made it very easy to implement radio communication in the
smart sensor design. The RC1090 works in the ISM frequency band at 915 MHz which is
usable in North America. The basic power and radio features are summerized in table 3 on
the following page.
Pg. 18
Table 3. Basic Parameters
Communication between two RC1090 modules is handled by the proprietary RC232
embedded RF protocol. This protocol is invisible to the user, but is versatile enough to be
configurable. The features of this protocol are:
 Un-buffered transparent mode
 Buffered packet transmission mode
 Variable packet length, end character or timeout
 Optional addressing of packets to a unique node, or broadcast to all nodes in a system
 Optional error detection using CRC-16 check sum
 On-the-fly configuration of the radio modem
The modules can transfer data via a UART interface to/from either a host MCU or
dedicated serial drivers. The interface to the module UART can be made with a simple two
wire connection- one for transmit, one for receive. The UART protocol used by the module is
a simple 8 bit, 1 stop bit, no parity. For communication with dedicated serial drivers, the
RC1090 is compatible with RS232, RS422, and RS485 serial buses. This communication is
again handled with the UART interface. Optional handshaking is also available through RTS
and CTS signals for both host communication and dedicated serial drivers. If these signals
are not used. It is recommended by the data sheets to connect them to the VDD pin. When
connecting to the RC1090, refer to the diagram below. For a complete pin description and
assignment refer to the RC10x0_Data_Sheet_1_3.pdf in Appendix D.
Figure 7. Connection to host MCU or RS232/422/485 drivers
The transceiver shown here has the on/off pin tied to Vcc. This option allows the transceiver
to be powered all the time. For control of the power, a separate line to a host MCU should be
Pg. 19
used. When turning the RC1090 on and off, the timing parameters and hardware control
specifications need to be considered for fault free operation. The time required from RESET
to IDLE state and OFF to IDLE state is 160ms. The wakeup time from SLEEP to IDLE is
55ms. Other timing parameters can be found on page 8 of the RC10x0 Data Sheet 1_3.pdf.
For the OFF mode, it is important to follow the note on page 5 of the RC10x0 Data Sheet
1_3.pdf to ensure power-on-reset. There are 3 options listed in the note depending on design.
For the smart sensor design, the ON/OFF pin was brought out to a header pin for control
from the PIC16F88. As well, the RESET pin was also brought out to the header via a
100kohm series resistor for control from the PIC16F88.
Output Software
RC1090 Configuration
The configuration of the RC1090 can be done through the host MCU or via the serial
drivers. To begin this process, the CONFIG pin is first pulled low then high. The
configuration data is then sent via the UART interface. Once in CONFIG mode, the
module will return a '>' prompt on the TXD pin. This indicates that the module is
ready to receive a command. Most commands are followed by arguments. For a
complete list of commands and arguments, refer to pages 5 to 9 in the RC232 User
Manual 1_4.pdf in Appendix C. The format for sending the configuration data should
be in hexadecimal.
If configuration is done via the host MCU, it needs to be able to read the '>' prompt
signal from the module before sending commands. A configuration program can be
sent to the host, then used to configure that actual module in circuit. This can be
very beneficial in the field. A simpler method for configuring the transceivers is
through the serial drivers. However, this needs to take place before installation. In
order to load the data onto the transceivers via serial drivers, a terminal program is
needed. This program needs to be able to send hexadecimal values from 0x00 to
0xFF. ASCII terminal programs, like Hyperterminal, will therefore not be suitable.
There are two types of memory that can be configured- the volatile memory and the
non-volatile memory. When configuring the volatile memory, all configuration will be
lost on reset or if the power supply is turned off. The parameters that were
configured for the smart sensor design are listed in table 4 on the following page.
Pg. 20
Table 4. List of Configuration data for the smart sensor
Parameter
Memory Configuration
Command in Address in Argument in
Hex
Hex
Hex
0x11
BROADCAST_ADDRESS
0x28
DESTINATION_ID
EXIT_MEM_CONFIG
Command to enter
into memory
configuration
0x40
PACKET_END_CHARACTER
0x21
0xFF
Note
0x0D
To start transmission,
send an ASCII 'CR' at
the end of the packet
0x39
Set broadcast
address to decimal 9
0x39
Set the destination of
the packet the same
as the broadcast_id
Exits out of memory
configuration
Pg. 21
For a step by step procedure for configuration of the RC1090 modules refer to the
table below.
Table 5. Procedures for Configuration
Module Input
Value
Module Response
Notes
>
Assert
CONFIG
A logic '0' form
the host MCU or
pull to GND if
using serial
drivers
1
none
De-assert
CONFIG
A logic '1' form
the host MCU or
pull to Vcc if
using serial
drivers
0x4D
>
0x11
none
0x0D
none
0x28
none
0x39
none
0x21
none
0x39
none
0
Memory
Configuration
Command
Send an End
Character
Character to
be sent
Broadcast
Address
Address
Destination of
Packets
Command to
write to memory
Address of value
to be changed
Write value of
ASCII 'CR' to
above address
Address of value
to be changed
Write value of
ASCII '9' to
above address
Address of value
to be changed
Address
Write value of
ASCII '9' to
above address
Exit Out of
Memory
Configuration
Command
Exits out of mem
config and puts
module into idle
state
0xFF
>
Pg. 22
PCB
The Design of the Printed Circuit Board
There were several steps involved in the process of designing the printed circuit board (PCB)
for the Whirl Wind Smart Sensor. For convenience, the PCB of the Smart Sensor was
designed using Protel 2004 DXP software. The advantage of creating a PCB using Protel is
that the creation of the schematic document and PCB document can communicate between
each other (refer to Appendix B).
The main aspects of designing the PCB of the Smart Sensor using Protel software are;
designing the footprint layouts of each component, drawing the dimensions of the board,
placing the components on the board, and routing all the traces.
Designing Footprints
Each component used in the circuit for the Smart Sensor must have a footprint layout. The
correct dimensions for the footprint are specified in the component datasheet. The Protel
library has most footprint layouts already designed, but for newer components, the footprints
have to be constructed manually and assigned to the component. Figure 8 displays the
footprint for the RS232 transceiver chip (ICL3221).
Figure 8. footprint layout of ICL3221
Board Dimensions
The PCB of the Whirl Wind Smart Sensor will need to fit inside the RM Young 05103
interface box. This enclosure of the RM Young Wind Sensor is small, therefore the entire
space must be utilised. The areas of the PCB that will require height restrictions on the board
are the connectors, potentiometer, and crystal. Tooling holes are required in the design of the
board for assembly and manufacturing processes. All these factors need to be defined before
the board can be designed, as well as, the maximum dimensions of the board and the location
of connectors and tooling holes. For a diagram of the board dimensions refer to Figure 9.
Pg. 23
Figure 9. PCB Dimensions
Placement of the Components
At this point, the placement of the parts on the board can begin. There are a number of
factors to be considered when placing parts, such as, electrical function, physical size,
temperature factors, minimum spacing, and routability. Start with placing all the fixed
location parts. These parts must be placed in certain locations for functionality purposes. On
the Whirl Wind Smart Sensor these parts include only the terminal connectors. The desired
placement of these parts is shown in Figure 10. The remaining components were placed as to
reduce trace length and to reduce the total amount of vias.
Figure 10. Fixed Location Parts
Pg. 24
Routing the Traces
Due to the small physical size of the board and the complexity of the circuit, routing all the
traces would be a difficult process. To make routing easier, the traces were connected
automatically using the autorouting capabilities of DXP Protel. To use DXP autorouting, a
netlist of all the connections must be constructed from the schematic document. This netlist
is then applied to the PCB document. Some unusual traces occurred during autorouting, but
were easily fixed by manually re-routing the trace. Figures 11 and 12 show the finished PCB
layout of the top and bottom sides respectively.
Figure 11. PCB layout of top side
Figure 12. PCB layout of bottom side
Pg. 25
Manufacturing of the PCB
The finished PCB design was then checked against the schematic for correct operation and
connectivity. The gerber and tooling files needed to create the physical board were
completed. The PCB was etched and drilled on a copper plated board at Camosun College as
shown in Figure 13. The components (surface mount and thru-hole) were manually
soldered. The vias had to be manually soldered too because this particular machine cannot
produce connected thru-hole pads.
Figure 13. PCB being etched at Camosun College
Wireless Transceiver PCB
The wireless transceiver (RC1090) was made on a separate PCB and connected to the main
board using an 8-pin header. The RC1090 is very susceptible to noise and interface and it
was concluded that a separate board with a large ground plane and separate supply voltage
would be the best solution to reduce the effect of noise. The process of building the PCB for
the wireless transceiver was constructed using the same steps as for the main board (refer to
Appendix B).
Pg. 26
Troubleshooting
Once the PCB was built, power was slowly applied to the Whirl Wind Smart Sensor and all
areas of the board for tested without no load at the outputs. After the Smart Sensor was
operating under no load correctly, then each transmission protocol was tested separately
starting with the RS232 and the RS485 transceivers. These transceivers were operating
properly as expected. The wireless transceiver (RC1090) showed signs of noise interference
even with the considerations already taken in the design of the RC1090 board. These
transmission errors were concluded to be the result of noise produced from the main board of
the Smart Sensor.
After extensively testing the Smart Sensor several intermittent faults appeared and the
original could not be detected. The source of these faults is considered to be the result of one
of the IC’s, but could not be concluded as time did not permit.
Recommendations
It is recommended that an alteration to the PCB design of the Whirl Wind Smart Sensor be
looked at to increase stability. A modification to the main ground trace should be considered
to increase the stability of the Smart Sensor to noise and other electromagnetic interference.
The best solution to achieve better stability is to connect the main ground trace in a complete
loop around the PCB and to increase the size of the ground plane. This will provide a better
suppression of unwanted signals.
References
1.) [1] RM Young 05031 data sheet See Appendix C
2.) [2] Intersil ICL3221 data sheet See Appendix C
3.) [3] Intersil ICL3221 data sheet See Appendix C
Pg. 27
Appendices
Appendix A Schematic
1
JP1
2
3
4
5
6
RM_Young_Header
VCC
4
COIL2 5
POY+ 4
POT X 3
POT- 2
COIL1 1
IC2D
TLV2404
13
14
12
A
A
11
WindDirectionPotentiometer (0- 10k)
-VCC
3.6864MHz
1
2
R6
XTAL
VCC
VCC
Trimmedto~10k
4
1
IC2B
TLV2404
6
R2
R4
7
5
IC2C
TLV2404
9
8
100K
VCC
C2
15pF
IC3
2
11
-VCC
R5
50K
11
-VCC
C1+
.047uF 4
C4
5
.33uF
-VCC
C1-
IC1
1
Ref level +
2
3
R10
Ref Level -
D2
4
VCC
1N4148
5
6
W3
R9
100K
7
C8
1uF
8
Jumper
9
VCC
C
RA0/AN0
RA4/AN4/T0CKI/C2OUT
RA7/OSC1/CLKI
RA5/MCLR/Vpp
RA6/OSC2/CLKO
Vss
Vdd
RB0/INT/CCP1
RB1/SDI/SDA
RB7/AN6/PGD/TIOSI
RB6/AN5/PGC/T1OSO/T1CKI
RB2/SDO/RX/DT
RB5/SS/TX/CK
RB3/PGM/CCP1
RB4/SCK/SCL
R1in
En
12
VCC
.33uF
13
C5
RS232Tx
R1out
1
17
7
!FORCEOFF
FORCEON
16
IC3221
INVALID
8
B
RS232Rx
16
10
VCC
15
D3
14
14
10K
Q1
MOSFET-N
RA3/AN3/Vref+/C1OUT
18
T1out
GND
R8
100K
RA1/AN1
100nF
C7
.33uF
3
T1in
9
RA2/AN2/CVref/Vref-
V-
C2-
VCC
R7
100K
V+
C2+
6
11
B
VCC
11
R3
5K
C6
C3
0-Vcc/2~
WindDirection
10
Var Res
100K
15
15K
3
C1
15pF
VCC
R1
4
Z2
Tranzorb
4
IC2A
TLV2404
2
Z1
Tranzorb
100K
VCC
13
GE
12
11
JP3
W1
Jumper
10
RS232Tx
RS232Rx
PIC16F88
RS485Tx
RS485Rx
R12
1
2
3
4
5
C
RS232/RS485_header
1M
5
IC6
OPA244
4
Sample Control Signal
D1
3.3V
RegEnable
VCC
1
8
3
Frequency ~
WindSpeed
1N4148
IC4
R15
1M
R13
100K
2
ON/OFF
3
R14
100K
4
3.3V
JP5
!RE
D/Z
DE
A/Y
7
6
RS485Rx
RS485Tx
DI
ISL83485
5
1
2
3
4
5
D
JP4
ICSP Connector
RegEnable
Title
1
2
3
4
5
6
7
8
5
4
3
2
1
RO
GND
RXEN
TXEN
CONFIG
TxD
RXD
VCC 3.3V -VCC
Q2
MOSFET-N
VCC
-VCC
D
1
W2
Jumper
2
R11
1K
Power
JP2
RC1090Header
Size
Number
Revision
B
Date:
File:
1
2
3
4
5
4/7/2005
Sheet of
C:\Documents andSettings\..\wind_sensor2[2].S
D
C
raw
HD
n
O
B
C
y:
6
Pg. 28
Appendix B - PCB
Top layer
Bottom layer
Pg. 29
Appendix C - Data Sheets
1. Intersil ICL3221 data sheet

http://www.intersil.com/data/fn/fn4805.pdf
2. Intersil ISL83485 data sheet

http://www.intersil.com/data/fn/fn6052.pdf
3. Microchip Pic16F88 data sheet

http://ww1.microchip.com/downloads/en/DeviceDoc/30487b.pdf
4. RadioCrafts RC1090 data sheet

http://www.radiocrafts.com/download.html
5. Texas Instrument TLV2404 data sheet

http://focus.ti.com/lit/ds/symlink/tlv2404.pdf
6. Texas Instrument OPA244 data sheet

http://focus.ti.com/lit/ds/symlink/opa244.pdf
7. RM Young MODEL 05103 Wind Monitor data sheet

http://www.cleanair.com/Equipment/Rentals/equip/manuals/RMYOUNG.PD
F
Pg. 30
Appendix D - Bill of Materials
Quantity
Part Number
1
PIC16F88-I/SO
IC1
1
TLV2404IPW
IC2
1
ICL3221IA
IC3
1
ISL83485IB
IC4
1
1
1
2
1
2
2
IC5
IC6
X1
D1,D2
D3
Z1,Z2
C1, C2
1
2
4
1
3
1
7
RC1090
OPA244NA/250
ATS037
1N4148
1N23
P6KE18
ECUS2A150JCA
GRM319R71H104KA01D
GRM319R71H335KA01D
GRM319R71H475KA01D
ECJ-3YF1E105Z
VN10KLS
929647-02-5-I
929647-02-8-I
929647-02-2-I
ERD-S2TJ102V
ERD-S2TJ104V
2
1
1
1
1
1
ERD-S2TJ105V
EVNDJAA03B15
ERD-S2TJ153V
ERD-S2TJ103V
ERD-S2TJ473V
ERD-S2TJ472V
1
3
1
Designator Description
C6
Microchip PIC16F88 – 18-pin enhanced flash microcontroller with
nanowatt technology
Operational Amplifier - 880-nA/Ch rail-to-rail input/output with
reverse battery protection
One microamp supply-current, +3V to +5.5V, 250kbps, RS-232
transmitters/receivers
3.3V, low power, high speed or slew rate limited, RS-485/RS-422
transceivers
Wide band multi-channel RF transceiver module
Micropower single-supply operational amplifier
Crystal oscillator 3.6864 MHz 15pF load capacitor
High conductance fast signal diode
Germanium crystal diode
Transzorb transient voltage suppressor
15pF, 100V 5% monolithic ceramic capacitor
0.1uF, 50V 10% ceramic capacitor
C4,C5,C7
0.033uF, 50V 10% ceramic capacitor
C3
0.047uF, 50V 10% ceramic capacitor
C8
Q1,Q2
JP1,JP3-JP5
JP2
W1-W3
R11
R4,R6-R9,
R13,R14
R12,R15
R2
R1
R10
R5
R3
1uF, 25V ceramic capacitor
N-channel enhancement-mode MOSFET - zener gate
5-pin header
8-pin header
2-pin header/jumper
Resistor 1kΩ carbon film 1/4W 5%
Resistor 100kΩ carbon film 1/4W 5%
Resistor 1MΩ carbon film 1/4W 5%
100k potentiometer 6mm carbon top adjustment
Resistor 15kΩ carbon film 1/4W 5%
Resistor 10kΩ carbon film 1/4W 5%
Resistor 47kΩ carbon film 1/4W 5%
Resistor 4.7kΩ carbon film 1/4W 5%
Pg. 31
Appendix E – Source Code
See attached.
Pg. 32