DETAILED DESIGN REVIEW:
Wireless Assistive Control System
Project 08027
Todd Bentley, ISE
Vianna Muller, EE
Benjamin Danziger, EE
Peter “PJ” Drexel, EE
Jay Radharkrishnan, EE
James Corcoran, CE
Dr. Edward Brown, Advisor
November 2nd, 2007
RIT Multidisciplinary Senior Design 1
Page 1 of 46
Design Review: Table of Contents
Function Diagram
Front End
Customer Needs for the Front End
Strap Design
BOM: Strap
Controlling Hand Movements
BOM: Electrodes
Test for Deciding Electrodes
Filter, Controller
Customer Needs for the Filter and DSP
Unfiltered EMG data
Filter types
Exploration of Crosstalk
DSP 537 Architecture
Control System Operation
Processing Requirements and Specifications
Audio System
Audio Interface
Audio Amplifier Design
BOM: Speaker Amplifier
Wireless System
RC Car
The QFD as it relates to the RC Car.
Microcontroller
Development Board
Programmer
RC Car Pseudo Code
Visual Feedback
BOM: RC Car
Bill of Materials
Page 2 of 46
3
4
5
7
9
10
10
10
11
11
13
14
15
21
26
28
30
30
31
31
32
34
34
35
36
38
40
42
45
46
Design Review: Functional Diagram
Right Thumb Left Thumb
Left Fingers
Right Fingers
Amplifier
Grass Tech. BF511
DSP
Development
Board (for
BlackFinn 533)
DSP:
Filter and Controller
BlackFinn 533
RF TX
Sound
Transmitted Commands
RF RX
Micro Controller
Motor
ATtiny2313
Motor
Figure 1: Overall System Functional Diagram
Page 3 of 46
Speaker
Left
Right
Forward
Reverse
Design Review: Front End
Right Thumb Left Thumb
Left Fingers
Right Fingers
Amplifier
Grass Tech. BF511
DSP
Development
Board (for
BlackFinn 533)
DSP:
Filter and Controller
BlackFinn 533
RF TX
Sound
Transmitted Commands
RF RX
Micro Controller
Motor
ATtiny2313
Motor
Figure 2: Front End Functional Diagram
Page 4 of 46
Speaker
Left
Right
Forward
Reverse
Category
Front End
Nu. Specification Units Ideal Marginal
A
Directs/Protects
EMG wires
A2
Ergonomic
Design, size ft
4 ±1
Universal Fitment
of glove
A3
Ergonomic
Design, size ft
2 ±0.5
1
Universal Fitment
EMG wires
A4
Ergonomic
Design, size in
8 ±5
1
Aesthetic value
("coolness")
A5
The "Fonze"
Factor
N/A
N/A
N/A
Secures EMG
pads in place
Durable
A6
A7
Location of
pads
Material
N/A
N/A
N/A
N/A
Comfortable to
wear
A8
Ergonomic
Design, size in
Safe Electrodes
and Wires
A9
Current into
the body
A
Electrode Size
A10 Radius
Page 5 of 46
N/A
N/A
Cm
8 ±5
3
1
1
Documentation
Wires must be easily able to connect to electrodes
Wires should be thin and insulated
Electrodes must be grounded consistently
Amplifier no more than 5 lbs
Guaranteed safety by manufacturer
High strength thread used for construction
Rating of the appeal of the glove to the customer.
Easily stored for extended periods of time
3
1
1
3
3
1
1
3
1
1
3
3
1
None None
2
Wear resistant straps
Velcro strong enough to hold without loosening
Strap length sufficient to wrap arm of most operators
Length of wires sufficient for most operators
Puts EMG wires and electrodes close to desired location
Customer Needs for the Front End
9
3
3
1
33
3
3
1
1
3
1
3
Anthropometric Summary(cm)
Wrist Breath
Female
Elbow Breadth
Male
Female
Wrist to Elbow
Male
Male
5th
95th
5th
95th
5th
95th
5th
95th
5th
95th
4.6
5.9
5.3
6.6
5.7
7.7
6.4
8.2
31.9
41.1
The wrist to elbow dimension requires a maximum only since anyone with arms
shorter than 41.1 centimeters will simply have a bit of slack between the wrist and
elbow points.
Summary of Specs and Anthropometric Basis
Desired
Spec
Strap
Anthropometric Data
Measure
Converted
Circumference
around elbow
Elbow Strap
Elbow Breadth is the diameter of the
elbow
8.2
10.1
Circumference
around wrist
Wrist Strap
Wrist Breadth is the diameter of the wrist
6.6
8.2
Length of wrist
to elbow
Connecting
Tube
Relates to the Wrist to Elbow Distance
41.1
16.2
Height from
wrist to thumb
Thumb Strap
No anthropometric data exists for such a
measure, convenient since it is not
necessary to know.
N/A
N/A
The final column represents a conversion of the anthropometric data from a diameter
to a circumference and converting the measure from centimeters to inches. The final
lengths of each strap will need to overlap so an additional 3 inches was added for the
Velcro overlaps.
--For the length of the wires from the electrodes to the pack
anthropometric data was used combining the 95th percentile for the reach
of the human male and the waist to shoulder height for the same male. The
length of the thenar-to-pack wire was found to be 4.5 feet and the length
of the finger flexors-to-pack wire was determined to be 3.5 feet. This would
allow the operator to control the vehicle with his or her arms over their
head.
**All Data Collected from NHANES/NCHS databases and Bodyspace by Stephen Pheasant.**
Page 6 of 46
Figure 3: Three-Dimensional View of the Strap
Page 7 of 46
Figure 4: Strap Components with Measurements
Page 8 of 46
BOM: Strap
Primary Sources
Item
1" Nylon Webbing
Quantity
(Roll)
1 - 50 ft Roll
Total Price
$22.90
1" Nylon Web Tubing
1 - 50 ft Roll
$20.50
2" Nylon Webbing
1 - 50 ft Roll
$30.50
1.0" Duragrip ™ Black Hook Std
1.0" Duragrip™ Black Loop SewOn
1 - 25 ft Roll
$12.50
1 - 25 ft Roll
$12.50
1" Ladder Locks
10 @ $1.17
$11.70
500 Denier Cordura Plus®
Page 9 of 46
1 yd
Sub-total
Est.
Shipping
Total
$13.40
$124.00
$20.00
$144.00
Controlling Hand Movements
One potential problem is the differences in a person’s movements were that they produce
varying signals. A solution to the problem is to have a hand controller that would limit
the variation of movements from operator to operator. This hand controller would consist
of something that will require the user to push inward using all four of their fingers, thus
maximizing the potential created by their flexors. Also, this hand controller will be
spring loaded, but testing purposes we would simply grip the controller we have now
with reasonable force. On top of the hand controller, there will be an analog stick much
like the current video game controller we are currently using. Ultimately, the analog
stick would have to move in only one direction but for out tests we will only move it
medially. This will control the contraction of the thenar muscle group in the thumb by
forcing the user flex their thumb inward.
BOM: Electrodes
Item
Source
1025 passive electrode
DDN 20 passive
electrode
Part # 243 (with GND)
Part # 242
The Electrode Store
The Electrode Store
Noraxon, USA, Inc
Noraxon, USA, Inc
Amount
Cost
Status
3 boxes $165 arrived
20 packages $110 arrived
1 TBD getting quote
1 TBD getting quote
This BOM pertains to the needs of the IRB and will depend on the following test.
Test for Deciding Electrodes
In order to decide which electrodes will work best, first we have to decide which type of
electrode is preferred: active or passive. Active electrodes have a preamplifier closer to
the muscle, thus improving the signal. Passive do not have this feature and depends on
the amplification provided by the Grass Technologies QP511.
To compare, the Meditrace passive electrodes will be used in a series of movements with
the electrodes places on the appropriate locations on their arm. Then, placing the active
electrodes in the same locations and performing the same movements. Finally, the
signals will be compared, after taking into account numerically for the pre-amplification
by normalizing the gains, which makes a visual determination of the noise possible.
Whichever produces the least noise will be the better choice. Our prediction is that the
active electrodes will prevail. However in the case where there is no significant
difference between the two signals concerning noise, the passive electrodes would be
preferred since they are less expensive.
Page 10 of 46
Design Review: Signal Processing
Right Thumb Left Thumb
Left Fingers
Right Fingers
DSP
Development
Board (for
Amplifier
Grass Tech. BF511
DSP:
Filter and Controller
BlackFinn 533
BlackFinn 533)
RF TX
Speaker
Sound
Transmitted Commands
RF RX
Micro Controller
Motor
ATtiny2313
Motor
Left
Right
Forward
Reverse
Figure 5: Data Processing Functional Diagram
Category
Filter/DSP
Sampling Rate
Acquisition Lines
Line to Transmitter
Line to Speaker
Page 11 of 46
Number
B
B1
B2
B3
B4
Specification
Units
Ideal
Marginal
Range
Input
Output
Output
second 10,000 ±250
N/A
4 >4
1
N/A
1
9
9
9
Documentation
Transfer Rate
Number of inputs for each
command and clarity
After A/D conversion, there
is a large number samples
Customer Needs for the Filter and DSP
1
1
1
1
9
Implementation of Filter in the system
The 4 lines of on analog data enter DAQ and leave digitized and enter MATLAB. From
here the filtration process will start. As of right now, a sampling frequency of 500Hz is
being used, the thumb uses 5k amplification and the forearm muscle uses 50K
amplification. After the data is obtained, the RMS is taken and then it will be filtered.
The movements used to obtain data will be categorized as A, B, C and D. The A and B
movements are on the right arm and the C and D movements are on the left arm. The A
and C movement uses the forearm muscles and the B and D movements use the thumb
muscle.
In senior design II, the filtration process ADC will happen inside of the DSP along with
the filtering. After the data is filtered, it is sent the control system to figure out how to
handle the data further.
Some unfiltered data can be seen on the following page. Note that the period of activity
is a rough estimate.
Page 12 of 46
Unfiltered EMG data after RMS
Figure 6: an example of the A movement
(50K amplification)
Figure 7: another example of the A movement
(50K amplification)
Figure 8: example of the B movement
(5K amplification)
Figure 9: another example of the A movement
(5K amplification)
Page 13 of 46
Filter types
From the International Encyclopedia of Ergonomics and Human Text, it is seen that the three main filters to
look at are a Low pass, a High pass and Notch filter.
The low pass will be used with a 600hz cutoff frequency when working with surface EMG and 1000Hz when
working with fine wire EMG to prevent aliasing. It is suggested to use an analog filter for this.
The High pass filter would be used with a 15 cutoff, due to the rapid hand movements to remove movement
artifacts. It is suggested to use a 4th order Butterworth filter.
The notch filter is used at 60Hz to get rid of noise from power lines.
From Muscles Alive by J.V. Basmajian, the limits of the EMG frequencies were observed to be 20Hz to
1000Hz
Working with RMS data
When working with the EMG signal, we want to work with the RMS data (root mean squared). In order to
replicate this on the grass QP511, the RMS function will have to be performed on the DSP.
An equation similar to this will have to be used.
Xrms 
( X 12  X 22  X 32  ...  X n2 )
n
Page 14 of 46
Exploration of Crosstalk
Shown in the following graph is data obtained of a person doing the A movement with electrodes on both the
arm and thumb. 50K amplification was used was the forearm while 5k was used on the thumb.
Cross talk with movement A
4.5
4
3.5
voltage (v)
3
2.5
2
1.5
1
0.5
0
-0.5
0
1
2
3
4
5
time (s)
6
7
8
9
10
Figure 10: Crosstalk on Movement A
In the next graph is data obtained of a person doing the B movement with electrodes on both the arm and the
thumb muscle group. 50K amplification was used was the forearm while 5k was used on the thumb.
Cross talk with movement B
4.5
4
3.5
voltage (v)
3
2.5
2
1.5
1
0.5
0
-0.5
0
1
2
3
4
5
time (s)
6
7
8
Figure 11: Crosstalk on Movement B
With these two movements, there is minimal cross talk to be seen.
Page 15 of 46
9
10
Smoothing Techniques
We looked at a couple of smoothing techniques to handle the data. We tried a moving average technique to
make the data more workable.
Here is the code for the moving average:
y= xlsread('C:\Documents and Settings\tkb1214\Desktop\test a-1');
y=y';
x=linspace(0,5,2500);
t=linspace(0,5,2500); %settign up the graph
%size of moving average
n=50;
out=linspace(0,0,2500)
%itterate over the lenth of the data starting from n points in
for i = n:length(y)
%copy the contents of our window into a temp array
for j=1:n
temp(j) = y(i-n+j);
end;
out(i) = sum(temp)/n;
end;
figure(1)
plot(t,y, 'b');
hold on
plot(t,out,'r')
ylim([0 5])
ylabel('Voltage (v)')
xlabel('Time (s)')
figure(2)
plot(t,y)
ylabel('Voltage (v)')
xlabel('Time (s)')
figure(3)
plot(t,out, 'r')
ylabel('Voltage (v)')
xlabel('Time (s)')
Figure 12: Moving Average Code
Page 16 of 46
5
4.5
4.5
4
4
3.5
3.5
3
3
Voltage (v)
Voltage (v)
5
2.5
2
2.5
2
1.5
1.5
1
1
0.5
0.5
0
0
0.5
1
1.5
2
2.5
Time (s)
3
3.5
4
4.5
0
5
0
0.5
1
Figure 13: Both the original and smoothed signal
1.5
2
4.5
4
Voltage (v)
3.5
3
2.5
2
1.5
1
0
0.5
1
1.5
2
2.5
Time (s)
3
3.5
Figure 15: The unsmoothed signal
Page 17 of 46
3
3.5
4
Figure 14: The smoothed signal
5
0.5
2.5
Time (s)
4
4.5
5
4.5
5
Control System
A proper model of the situation is necessary before designing the control system. This section extensively
describes the model and logistics of the control system. How the control system fits into the overall project
architecture is shown in the block diagram below. The controller and the digital filter is both implemented in the
DSP processor.
DIGITAL
FILTER
CONTROL
SYSTEM
WIRELESS
Tx
Figure 16: System architecture under scrutiny
The Control system was designed qualitatively by modeling the situation at hand. For instance, the situation is
presented where a muscle is flexed from its initial rest position at point (a) in the figure below to the point (b)
and returned back to its original rest position. The user’s motion does not have to be like this; however it
represents the range of force exerted by any muscle. The EMG data is recorded to process and develop the
control system in a similar manner.
Figure 17: The range of movement of muscle under scrutiny
The figure 3 below shows how this can be represented through a graph. The points (a) and (b) from
figure 1 is shown on the figure 2. This graph can be seen as the input to the controller. The only exception is
that 4 different muscles excerpt properties in a similar manner. The 4 different muscles exhibit the same range
of force. IT SHOULD BE NOTED THAT THESE GRAPHS ONLY MODEL THE SITUATION AND DOES
NOT REFLECT ANY EMG DATA.
Page 18 of 46
Figure 18: Controller input model
For this project we have 4 different muscular inputs that translate to subsequent outputs that go through a
wireless transmitter to the RC car. For instance how one input is related to the output is shown in figure 4
below.
Figure 19: Relationship of EMG input data to move left to the output on the RC car
It can be noted that the EMG data to move right works in a similar way, except the output will be taking into
account the range in which the tires of the RC car turn right. However, the input-output relation to move
forward and backward is slightly different. This is more clearly shown in figure 5 below.
Page 19 of 46
Figure 20: Relationship of EMG input data to move forward to the output of the RC car.
Here, it can be seen that the input is tied to the velocity of the RC car to move forward. The same
relationship is applied to move the car backward. This whole modeling idea is influenced from fuzzy logic
modeling. However, the lack of overlapping membership functions, made full fledged implementation of fuzzy
logic unnecessary and impractical. However, concepts from fuzzy logic are used in this digital controller.
A much clear representation of this modeling is shown in figure 6 below.
Figure 21: The explicit modeling of the control system
Everything explained till now is shown in the figure above. How the force excerpted by the muscle should
translate to the movement of the RC car is explained in the figure above. A further explanation of how this is
done in the DSP processor is explained below.
Page 20 of 46
DSP 537 Architecture
Figure 22: BF537 Board Architecture
It can be seen from the figure above that the processor does not have an in-built ADC or DAC. The ADC and
DAC are both peripheral devices on the Development board.
General-Purpose IO
This section describes general-purpose IO signals that are controlled by means of setting appropriate registers of
the flash A or flash B. These registers are mapped into the processor’s address space, as shown below.
Page 21 of 46
Table 1: Flash Memory Map on BF533
Flash device IO pins are arranged as 8-bit ports labeled A through G. There is a set of 8-bit registers associated
with each port. These registers are Direction, Data In, and Data Out. It could be noted that the Direction and
Data Out registers are cleared to all zeros at power-up or hardware reset. The Direction register controls I/O
pins direction. When a bit is 0, a corresponding pin functions as an input. When the bit is 1, a corresponding pin
is an output. This is an 8-bit read-write register.
The Data In register allows reading the status of port’s pins. This is an 8-bit read-only register. The Data Out
register allows clearing an output pin to 0 or setting it to 1.
This is an 8-bit read-write register.
Table 2: Flash A configuration registers for Ports A and B
Figure 8: ADC connector jack on the development board
Page 22 of 46
The EMG signals need to be hooked up directly the four input pins of J5, these input pins are hooked up to the
ADC at pins 16-19, and pins 22-26.This is clearly shown in the figure below. Also, the analog signal is
amplified by ADI amplifier that has a 120 dB open loop gain, low noise, low input bias current and low offset
voltage.
Figure 23: Audio Codec with ADC and DAC pins
The figure above also shows the pins for serial communication, these are pins SCK MOSI MISO and PF4 (Pins:
50, 51, 2, and 49). The MOSI signal is for the SPI bus, and MISO is the pin through which data is brought to
the board through the 90-pin connector. This is clearly shown in figure 9 and 10.
However, the reset for the ADC (AD1836) is controlled by the GPIO pin PA0 in flash A. How it is connected
on the 90-pin connector is shown in figure 10 below. Also, the pins of interest are circled in red as seen in the
figure. The GPIO’s subsequent connection on the processor is shown in figure 11. The serial peripheral
interface (SPI) of the ADSP-BF533 processor connects to the AD1836 audio codec and the expansion interface.
The SPI connection to the AD1836 is used to access the control registers of the device. The PF4 flag of the
processor is used as the devices select for the SPI port. The SPI signals are available on the expansion interface
and on the SPI connector (P6). The inputs are available on the board as two stereo headphone jacks. These
inputs are then connected to IN1R+/-, IN1L+/- and IN2R+/-, IN2L+/- respectively on the AD1836 chip. This is
clearly shown in figures 8 and 9.
Page 23 of 46
Figure 24: J2 connector on the Development board
Analog-to-Digital Converter (ADC)
The AD1836 is a high-performance, single-chip codec providing three stereo DACs and two stereo ADCs. A
SPI port is included, allowing a microcontroller to adjust volume and many other parameters. On the ADC, the
analog inputs are multiplexed on a single ADC per channel. As shown in the figure below the left channels are
Page 24 of 46
multiplexed on one ADC and both right channels are multiplexed on the other ADC. In the figure below, it can
be seen there are four inputs to the ADC. The four EMG signals will be hooked up to these inputs. Therefore,
the right arm’s data will be connected the AIN2L1 and AIN2L2, and the left arm’s data will be connected to
AIN2R1 and AIN2R2. These inputs are selected because the ADC will be operating in the Time-Division
Multiplexed (TDM) mode.
Figure 11: Functional Block Diagram of the ADC (AD1836)
Page 25 of 46
Control System Operation
How the control system functions will be explained in detail in this section. At this point, it is assumed that the
digital filter cleans out the raw EMG data. The filtered EMG data is fed to the controller; this is clearly shown
in the figure below.
LEFT
INPUT
DIGITAL
FILTER
FILTERED
DATA
RIGHT
INPUT
CONTROL
SYSTEM
WIRELESS
TRANSMITTER
FORWARD
INPUT
BACKWARD
INPUT
Figure 25: Detailed operations diagram of the control system
The controller accepts the inputs and transmits 8 bits of data as the output through the wireless transmitter. The
controller logic is pretty important in deciding the output and is briefly explained here. The truth table clearly
shows the situations in which a particular output can be high.
Left (i)
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Right (i) Forward(i)
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
Reverse(i)
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Left(o) Right(o) Forward(o)
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
1
0
0
1
1
0
1
0
1
0
0
1
0
0
1
0
1
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
Table 1: Truth Table for the input-output relation
The truth table can be summarized to the follow assumptions:
Left output is high when the Left input is high and when the Right input is low.
Right output is high when the Right input is high and when the Left input is Low.
Forward input is high when the Forward input is high and when the Reverse input is low.
Reverse input is high when the Reverse input is high and when the Forward input is low.
Page 26 of 46
Reverse(o)
0
1
0
0
0
1
0
0
0
1
0
0
0
1
0
0
Depending on the inputs, the output that will go through the wireless transmitter is an 8 bit number. How the 8bit data is allocated is shown in the figure below.
Figure 26: Bit allocation for the 8-bit output
From the above figure, it is apparent that there are 16 positions for forward/Reverse Directions and 16 positions
for Left and Right Directions.
All of this information is integrated using the following pseudo code:
a= 4bits of information for right/left turn
b=4bits of information for forward/reverse direction
If (left amplitude > right amplitude)
Then (resulting left turn= (left – right) of a’s left magnitude)
If (right amplitude > left amplitude)
Then (resulting right turn = (right-left) of signed a’s magnitude)
If (right amplitude = left amplitude)
Then (a=0000)
If (forward amplitude > reverse amplitude)
Then (resulting forward magnitude = (forward – reverse) b magnitude)
If (reverse amplitude > forward amplitude)
Then (resulting reverse magnitude = (reverse – forward) signed b magnitude)
If (forward amplitude = reverse amplitude)
Then (b=0000)
This clearly means that each direction’s magnitude is divided into 8 divisions. Also, the control system is itself
an open loop control system were the only feedback is the user’s eyes. Also it can be seen that the user is the
actual control system while the digital controller could be seen as a simple interface, since no major control
algorithms are being used there. How the pseudo code works is demonstrated through the figures below.
After the entire signal processing work is and a signal as showed in the figure below is obtained to move the car
forward. Here, the magnitude is divided into major 8 divisions that represent the 7 different speeds to move
forward. The 8-bit output value it translates to is shown in the figure below. Here, it could be assumed that only
the data to move the car forward is excited.
Page 27 of 46
Figure 27: 8-Bit output relation to filtered signal
Processing Requirements and Specifications
For this project the Nyquist frequency is fN= 1kHz.
Thus:
fS ~ 10 fN = 10kHz
Therefore: BW = 10kHz
Thus the dynamic range for the Analog to Digital converter is from 1 kHz to 15 kHz. This results in a dynamic
range of 23.52dB.
A total of 1 GPIO is needed; this is the 1 GPIO through which the output from the controller to wireless
transmitter. Four inputs to the ADCs for the four EMG signals. Also 1 GPIO is necessary for the audio feedback
that was recently added to this project.
The 4 EMG input signals needs to be sampled simultaneously than serially. Although multiplexing 2 inputs
such as forward and reverse as one along with right and left as another might workout.
The Resolution was calculated thus: Range from Highest observed EMG amplitude to Lowest observed EMG
amplitude = 5Vto -5V = 10. A resolution of 24 bits is used because this is the highest resolution at which the
ADC can operate; also this yields the optimal results.
The other major issue is the skew rate: Since the sampling frequency is assumed to be 10 kHz, the Skew rate is
calculated as shown in the figure below:
Page 28 of 46
Figure 28: Skew rate calculation
It is apparent from the figure above that skew rate is 0.3ms. This translates to a frequency of (10/3) kHz, which
is quite negligible considering the sampling frequency, is around 10kHz. Should this sampling frequency proves
not be sufficient, it can be increased to the desired frequency.
The Time frame for the DSP is normally the time taken by the DSP to process the whole process. This is
calculated as the sum of the processing times for each of the individual components:
Asynchronous Memory Read Cycle Timing = 6ns+6ns+6ns=18ns
Asynchronous Memory Write Cycle = 4(6ns) =24ns
SDRAM Interface Timing = 2(6ns) +2(4ns) =20ns
Parallel Peripheral Interface (PPI) Timing: 9ns+8ns=17ns
Serial Ports-External Clock = 4(10ns) =40ns
Serial Port-Internal Clock =3ns+3ns =6ns
Serial Port-Enable and Three State=10ns+3ns=13ns
Serial Peripheral Interface (SPI) Port Master Timing = 4ns+6ns+7.5ns=17.5ns
SPI Slave Timing = 10ns+10ns+8ns+8ns=36ns
GPIO Port Cycle Timing=2(6ns) =12ns
JTAG Port Timing=10ns+12ns+20ns+12ns+5ns+4ns=63ns
Approximate Code Processing Time=12ms
Total time frame for the DSP is about 15ms.
The other memory requirements include about 800kb for Audio storage, 5kb for u-boot and other boot files,
and about 20kb for coding. This sums to about 825kbs of memory that needs to be saved on the flash memory.
The flash memory has 2MB of memory. Therefore, it might be enough for this project.
Other power specs include a 7.5V input voltage for the BF533 Ez Kit Lite, with a regulator of 5V and 3.3V.
Page 29 of 46
Design Review: Audio System
Right Thumb Left Thumb
Left Fingers
Right Fingers
Amplifier
Grass Tech. BF511
DSP
Development
Board (for
BlackFinn 533)
DSP:
Filter and Controller
BlackFinn 533
RF TX
Sound
Transmitted Commands
RF RX
Speaker
Micro Controller
Motor
ATtiny2313
Motor
Left
Right
Forward
Reverse
Figure 29: Audio Capability Functional Diagram
Audio Interface
The AD1836 audio codec provides three channels of stereo audio output and two channels of multichannel 96
kHz input. The SPORT0 interface of the processor links with the stereo audio data input and output pins of the
AD1836 codec. The processor is capable of transferring data to the audio codec in time-division multiplexed
(TDM) or two-wire interface (TWI) mode.
The TWI mode allows the codec to operate at a 96 kHz sample rate but limits the output channels to two. The
TDM mode can operate at a maximum of 48 kHz sample rate but allows simultaneous use of all input and
output channels. When using TWI mode, the TSCLK0 and RSCLK0 pins, as well as the TFS0 and RFS0 pins of the
processor must be tied together external to the processor. This is done through the SW9 DIP switch.
The AD1836 audio codec’s internal configuration registers are configured using the SPI port of the processor.
The processor’s PF4 programmable flag pin is used as the select for this device. The general-purpose IO pin PA0
of flash A is a source for the AD1836 codec reset. In this project, TDM mode will be implemented because this
is the only mode in which simultaneous EMG inputs can be used.
Page 30 of 46
Audio Amplifier Design
Figure 30: Basic Amplifier design for the speaker
BOM: Speaker Amplifier
Part
LM358 Amp
Cap .01 uF
Cap 3.3 uF
Cap 100 uF
Res 1M
Res 3.3k
Res 10k
Res 6.8k
Res 4.7k
BJT 2N4403
BJT 2N4401
Bread Board
Speaker
Quantity
2
2
1
1
3
2
1
1
2
1
1
1
1
Overall Cost
Page 31 of 46
Cost (each)
$
0.45
$
0.17
$
0.16
$
0.14
$
0.26
$
0.04
$
0.04
$
0.04
$
0.04
$
0.04
$
0.04
$
2.50
$
-
Total Cost
$
0.90
$
0.34
$
0.16
$
0.14
$
0.78
$
0.08
$
0.04
$
0.04
$
0.08
$
0.04
$
0.04
$
2.50
$
$
5.14
Design Review: Wireless Communication
Right Thumb Left Thumb
Left Fingers
Right Fingers
Amplifier
Grass Tech. BF511
DSP
Development
Board (for
BlackFinn 533)
DSP:
Filter and Controller
BlackFinn 533
RF TX
Speaker
Sound
Transmitted Commands
RF RX
Micro Controller
Motor
ATtiny2313
Motor
Left
Right
Forward
Reverse
Figure 31: Wireless Functional Diagram
Wireless System
The wireless link between the DSP and RC car consists of a paired ASK transmitter module with an
output of up to 8mW depending on power supply voltage and a receiver with a sensitivity of 3uV.
 Frequency: 434 MHz

Range: 500 ft

Max Data Throughput: 4800bps

Transmitter Voltage Range: 2 – 12V (connected to 5V from regulated supply on DSP board)

Receiver Voltage Range: 4.5 – 5.5V (connected to 5V supply on vehicle)

Optional Antenna: 30-35cm of wire
Page 32 of 46
The data communications protocol for the wireless communications system is quite simple.
Each transmitted data sample will consist of 3 8-bit bytes. To operate properly, the wireless link
must transmit data which has approximately neutral disparity (#0’s:#1’s = 1). The first byte of
this sample will consist of a start byte, which will indicate to the receiver that data is being sent
to it. To indicate the beginning of a data transmission the transmitter will send a header byte
having neutral disparity (eg. 0xAA, 0x55). Subsequently, the transmitter will send the packet
described earlier consisting of the sign and magnitude information for the motor controls. Lastly
the compliment of the second byte will be transmitted. This will allow for neutral disparity of the
data transmission to be preserved, while also allowing for error detection on the receiving end.
The design of this communications protocol will limit data transfer to a maximum of 150
samples/sec.
Figure 32: Wireless Transmitter/Receiver Hardware
Page 33 of 46
Design Review: RC Vehicle
Right Thumb Left Thumb
Left Fingers
Right Fingers
DSP
Development
Board (for
Amplifier
Grass Tech. BF511
DSP:
Filter and Controller
BlackFinn 533
BlackFinn 533)
RF TX
Speaker
Sound
Transmitted Commands
RF RX
Micro Controller
Motor
ATtiny2313
Motor
Left
Right
Forward
Reverse
Figure 33: Robot Functional Diagram
Control
µProcessor
Power
Page 34 of 46
Marginal
Length
Width
Max Weight
Transmission range
Minimum turning radius
Accuracy of Path
Sufficient PWMs
Minimum battery life
Minimum battery supply voltage
in
in
lb
m
ft
in
#
min
V
12
6
< 10
150
2
±3
2
60
6
20
8
< 20
50
5
±3
2
45
>6
1
1
1
1
1
1
3
3
3
3
1
9
3
3
Documentation
Ideal
Must be relatively small chassis
Units
Vehicle is aesthetically pleasing
Specification
Efficient control of all drives/servos
Number
C
C1.1
C1.2
C1.3
C2.1
C2.2
C2.3
C3.1
C4.1
C4.2
Vehicle Easily Controlled
Category
Proof of Concept
Chassis
Vehicle Must receive RF commands
The QFD as it relates to the RC Car.
1
1
1
1
1
1
1
1
1
Microcontroller

The microcontroller being used for the task of controlling the vehicle is the ATTiny2313.
Up to 20 MHz operating frequency

8bit processor

15 I/O Lines

UART compatible pins

Data and Non-volatile program and data memories
o 2K Bytes In-System Self Programmable Flash
o 128 Bytes In-System Programmable EEPROM
o 128 Bytes Internal SRAM

One 8bit Timer/Counter

One 16bit Timer/Counter

Four PWM Channels

Operating Voltage Range: 2.7 – 5.5V (@10MHz)

Typical Power Consumption
o Active Mode

1MHz, 1.8V: 230uA
o Power-down Mode

Page 35 of 46
<0.1uA at 1.8V
Figure 34: ATtiny 2313 Microcontroller
Microcontroller Development Board:
Figure 35: Microcontroller Development Board Schematic
Page 36 of 46
Microcontroller Development Board:
Description:
Prototype board for 20 pin AVR microcontrollers with power supply circuit, crystal oscillator circuit, RS232
port, reset IC, status LED, 10 pin STK ICSP port.













ICSP 5x2 pin connector for in-circuit programming with AVR Programmers
Voltage regulator +5V or 3.3V, LM317
Quartz crystal oscillator circuit: 10Mhz
Reset IC ZM33064
Status LED connected to PB7 via removable jumper
AGND-GND AVCC-VCC jumpers
DIL28 microcontroller socket
RS232 DB9 female connector
RS232 MAX232 interface circuit with Tx, Rx, CTS, DTR/RTS signals
Extension slot on every uC pin
Grid 100 mils
GND bus
Vcc bus
Page 37 of 46
Microcontroller Programmer:
Description:
AVR-PG1B is programmer based on serial port PonyProg design. It takes the power supply from the target
board. The connector is 2x5 pin with 0.1" step and Atmel STKxxx compatible layout.
Figure 36: Microcontroller Programmer
Page 38 of 46
C9
U1
22p
Q
10 MHz
C10
22p
0
5
4
1
12
13
14
15
16
17
18
19
U4A
5
6
7
8
4
3
2
VCC
VCC Data
GND Data
GND
ANT GND
ICSP
ICSP
ICSP
1
10
MO-RX3400
PA0/XTAL1
PA1/XTAL2
PA2/RESET/DW
20
VCC
V1
2
3
6
7
8
9
11
PD0/RXD
PD1/TXD
PB0/AIN0/PCINT0
PD2/CKOUT/XCK/INT0
PB1/AIN1/PCINT1
PD3/INT1
PB2/OC0A/PCINT2
PD4/T0
PB3/OC1A/PCINT3
PD5/OC0B/T1
PB4/OC1B/PCINT4
PD6/ICP
PB5/MOSI/DI/SDA/PCINT5
PB6/MISO/DO/PCINT6
PB7/UCSK/SCK/PCINT7
R3
1k
BUT
0
2
0
U6
R4
1
2
3
Wireless receiver
A0
A1
A2
Microcontroller
THERMAL FLAG OUTPUT
8
CURRENT SENSE OUTPUT
10
2
OUTPUT 2
OUTPUT 1
VS POWER SUPPLY
GROUND
9
DIRECTION INPUT
PWM INPUT
BRAKE INPUT
BOOTSTRAP 2
C6
BOOTSTRAP 1
3
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
15
14
13
12
11
10
9
7
R5
R6
100
R8
100
R10
100
R7
100
R9
100
R11
100
100
100
5
Left
Side
74F138
4
11
1
C7
6
4
11
1
7
U3
LMD18200
C5
10n
U5B
18
GND
6
VCC
17
10n
10n
DC Motor
Steering
V2
6Vdc
OUTPUT 2
OUTPUT 1
C5
10n
Rear
0
U7
R12
1
2
3
10
2
THERMAL FLAG OUTPUT
CURRENT SENSE OUTPUT
8
U2
LMD18200
BOOTSTRAP 2
BOOTSTRAP 1
5
PWM INPUT
BRAKE INPUT
3
DIRECTION INPUT
GROUND
VS POWER SUPPLY
9
0
Right
Side
GND
0
7
3.3Vdc
1
ATTINY 2313
0
C11
100n
18
GND
VCC
A0
A1
A2
17
DC Motor
Acceleration
Motor Controls
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
15
14
13
12
11
10
9
7
R13
R14
100
100
R15
100
100
R19
100
74F138
R16
100
R18
100
R17
100
0
Visual Feedback
Title
RC Vehicle Schematic
Size
B
Date:
Figure 37: RC Vehicle Circuit Schematic
Page 39 of 46
Document Number
<Doc>
Wednesday , October 31, 2007
Rev
1
Sheet
1
of
1
RC Car Pseudo Code:
The RC Car must accept digital control information from a wireless source and translate
this information into direction and magnitude information which will control the motors.
The RC vehicle will utilize interrupt driven subroutines for both of these tasks. As shown
in the Vehicle Circuit Schematic, the wireless transmitter will interface directly to the
microprocessor through a digital input on pin 16 (PB4). Upon receiving data an interrupt will be
thrown causing the received data to be verified. To indicate the beginning of a data transmission
the transmitter will send a header byte having neutral disparity (eg. 0xAA, 0x55). Upon
identifying this byte subsequent data will be accepted, otherwise the byte is dropped and further
data is not stored. Upon receiving a header successfully two additional bytes will be accepted.
The first is the data byte and the second is its compliment. If the addition of these two bytes is
equal to zero, the first byte will be stored for later use in the motor control subroutine. The
design of this communications protocol will limit data transfer to a maximum of 150
samples/sec.
The motor control subroutine references a stored byte to update the motor control
parameters. This subroutine is executed at a set interval and in effect will control how frequently
the robots motor parameters will be changed. This subroutine will parse the stored data byte for
direction and magnitude information for the forward/reverse and left/right motors.
It is estimated that code requirements to implement the functions necessary for the
operation of the vehicle to be approximately 1K bytes.
//Receive wireless data
//Enter from receive interrupt
wait:
Read in a byte from the serial connection
Clear Receive Interrupt and Disable interrupts
If byte is equal to start byte
Get byte1
Get byte2 //We expect byte2 to be the compliment of byte1
If( byte1 + byte2 == 0)
store byte1 to MotorByte
else
Toss bytes
else
continue to wait for start byte
Enable interrupts
//Setup Motors
//Enter from timed interrupt at least 30 times/sec
//Forward/Reverse Motor Controls
mask upper four bits of MotorByte
Set fwd/rvs direction based on bit 3
Set fwd/rvs PWM based on bits 0-2
Move lower 3 bits to mux to update fwd/rvs LEDs
//Right/Left Motor Controls
shift MotorByte right 4
mask upper four bits of MotorByte
Set left/right direction based on bit 3
Set left/right PWM based on bits 0-2
move lower 3 bits to mux to update left/right LEDs
Figure 38: RC Car Circuit Board Placement Mock-U
Page 40 of 46
Figure 39: RC Car Circuit Board Placement Mock-Up
Page 41 of 46
Visual Feedback:
Concern was expressed in the proposed control design in the fact that there will be little
feedback to the user to indicate how the vehicle is responding to a user’s actions. One
mechanism devised to provide feedback on the actions being received by the vehicle is through
lighted indicators on the sides and rear of the vehicle.
It is intended that these be composed of individual LEDs aligned linearly on the sides and
rear of the vehicle (as shown in the images to follow). These lights would range in color from
green yellow  red. The different colors will be used to indicate a magnitude of direction. For
example, if the user is turning left, the LEDs at the back of the vehicle will light the left half of
the LEDs according to the magnitude of the direction. Similarly if a user is driving forward, the
lights positioned at the side of the vehicle will light indicating magnitude of direction in the
forward or reverse direction.
These Lights will be connected to a 3-to-8 multiplexor which in turn will connect to the
digital outputs of the ATtiny2313. A total of 8 discrete levels of magnitude will be able to be
indicated in the left/right directions and the forward/reverse directions.
The lights will be installed behind a plastic cover which lies flush with the truck body.
The plastic cover and the packages of the LEDS can be sanded to help diffuse the light and
create the appearance of a clean transition between colors.
Page 42 of 46
Figure 40: RC Car Side Lighting Mock-Up
Page 43 of 46
Figure 41: RC Car Rear Lighting Mockup
Page 44 of 46
BOM: RC Car
RC Vehicle BOM
Component
ATtiny2313
AVR Dev board
Power Supply
Serial Cable
Programmer
H Bridge
DC Motor (Forward/Reverse)
DC Motor (Left/Right)
Wireless Link 315MHz
Wireless Link 434MHz
RC Car
5mm Red LED
5mm Green LED
5mm Yellow LED
3-to-8 Multiplexor
10 pin 100Ω Resistor
network
Total Cost
Page 45 of 46
Quantity
3
1
1
1
1
1
1
1
1
1
1
Retail Link
Link
Link
Link
Link
Link
Sampled
From RC Car
From RC Car
Link
Link
WalMart
Cost/Item
$2.88
$16.95
$5.95
$3.95
$12.95
$0.00
$0.00
$0.00
$16.95
$16.95
$19.97
Total Component Cost
$8.64
$16.95
$5.95
$3.95
$12.95
$0.00
$0.00
$0.00
$16.95
$16.95
$19.97
20
20
20
10
Link (152805)
Link (1586197)
Link (152792)
Link (835315)
$0.19
$0.65
$0.17
$0.20
$3.80
$13.00
$3.40
$2.00
10
Link (280671)
$0.26
$2.60
$127.11
Design Review: Bill of Materials
Comprehensive Bill of Materials
System
Front End
Signal Processing
Audio
Proof of Concept
Comprehensive BOM
Number of Parts
16***
Strap
16
Amplifier
NA
Dev Board
1
Amp
19
93
Wireless System
2
Car with Supplies
91
Total Parts
129***
Subsystem
Subsystem Cost
Total Cost
$
$
$
$
$
519.00*
$
$
250.00
5.14
$
33.90
93.21
Total Cost
901.25 $
127.11
$
$
*The cost of the active electrodes were unknown at this time.
**Shipping is unknown for these items
***The electrode equipment is not accounted for
Page 46 of 46
144.00
375.00*
250.00
5.14**
901.25