AFeL
(Audio FM Link)
Service Manual
Senior Design Fall Semester 2001
Team Number: 16, FM Link - Blue
Project Sponsor: Dr. Matthew Valenti
Manual Author: Elizabeth S. Cullinan
Date: 12 December 2001
1
Table of Contents
Contents
Page
Introduction-------------------------------------------------------------------------3
Circuit Description-----------------------------------------------------------------4
Separate Parts List-----------------------------------------------------------------6
System Layout---------------------------------------------------------------------9
FM-25A Layout
Schematics------------------------------------------------------------------------10
USB – PIC Schematic
FM Receiver Schematic
Transmitter Schematic
Software List---------------------------------------------------------------------13
Software Code-------------------------------------------------------------------14
First Code
User Software
PIC Code
Troubleshooting----------------------------------------------------------------28
FCC Rules & Regulations----------------------------------------------------29
References for Specifications-----------------------------------------------30
2
Introduction
Welcome to the AFeL Service Manual. In here you will find all the
information you will need to completely understand the AFeL’s components
and how they work together. You will also be able to use this to
troubleshoot any problems you may encounter with the AFeL.
As discussed in the User’s Manual, the AFeL is a personal unlicensed, lowpowered FM Broadcasting system controlled by your PC. The AFeL is
made of two main components: it’s hardware and it’s software. The AFeL’s
hardware consists of the unlicensed, low-powered FM Transmitter, a FM
Receiver, USB cable and a microcontroller. The AFeL’s Software consists
of a user interface run on the PC and embedded software found in the
microcontroller.
The AFeL does transmit on an unlicensed FM broadcasting station in which
the United States embarks the FCC Rules & Regulations. It is vital that you
understand these rules. Please refer to the FCC Rules & Regulations chapter
of this manual for further information.
3
Circuit Description
Power Supply
The AFeL DC power supply is originally provided as a part of the
Ramsey™ FM-25A kit. 1While a DC power source is provided with the
FM-25A, the DC isn’t proper enough to provide us with the low-noise,
stable supply that we would like for a good audio quality. The Voltage
Regulator VR3 provides us with the means to take the raw DC output from
the wall transformer and smooth it out, keeping it at a constant 12 volts.
USB
The USB provides the communication between the PC User interface
(software) and the PIC microcontroller (hardware). The USB tells the PIC
which hardware component to turn on/off and what frequency to use. The
USB returns a ‘go’ or ‘no-go’ information form the PIC to the PC. The USB
has four Pins: Power, ground, D1 & D2 used to pass and receive data.
Microchip™ PIC16745
The Microchip™ PIC16745 microcontroller is the brains of the transmitter
and receiver. The PIC tells the transmitter and receiver when to turn on or
off and what station to transmit or receive. Without the PIC, the transmitter
and receiver would do nothing. The PIC, upon power-up, sets the PLL of
the transmitter then configures and initiates the USB. The frequency is set
to the Transmitter and transmission will begin. Please refer to the PIC
schematic for input/output specific pins.
Receiver
The Receiver is used to scan the licensed FM band (88-108 MHz) in order to
detect an open, or unused frequency. The components in the diagram
consist of the front-end chip, receiver chip and the PLL chip.
1
Note: Technical/Use information concerning FM25A kit taken directly from Ramsey™ User Manua
4
1
Transmitter
Once transmitter receives the information from the PIC, the PLL U1 takes
the 6MHz crystal frequency and divides it by 60 to obtain a stable frequency
of 100KHz. Your desired frequency is sent to the PLL in a string of binary
bits. The PLL is used to constantly check the output frequency so that it
matches the desired frequency. The PLL also takes the output frequency
from U3 and divides it by a number N. N is your desired frequency in
megahertz times 10.
The frequency from U3 is divided by N and compared to 100 KHz. If N is
less than 100KHz, the PLL will increase the output voltage (pin 13). This
will increase the voltage across the varactor diode D21 that will in turn cause
a decrease in the capacitance. The final result is an increase in U3’s RF
oscillator, and keeping the output frequency on track to match your desired
frequency. The opposite occurs when N is more than 100 KHz.
Adjustable Components
There are five potentiometers found in the hardware; three located in the
transmitter circuit and two located in the receiver circuit. 2The transmitter
potentiometers R11 and R16 allows for the adjustment of the audio levels.
The transmitter potentiometer R6 permits adjustment of stereo balance. The
receiver potentiometer RP1 is used in place of 22ohm resister and should
never be adjusted. The receiver potentiometer RP2 allow for adjustment of
the FM tuning level.
1
Information concerning the FM25A is taken directly from FM25A user manual.
l.
5
The FM Link Parts List
1
1
1
1
6 foot USB Cable Cord
Radio Shack Black Project Box 7x5x3
Shielded stereo audio cable
Micro-Controller Circuit
1
Microchip PIC 16C745
1
220 μF, ceramic capacitor
1
100μF, ceramic capacitor
1
1.5K ohms (brown – green – red) resistor
1
Receiver Circuit
Capacitors
5 .01μF disc capacitors
1 .017μF disc capacitor
2 .022μF disc capacitor
2 .03μF disc capacitor
2 .033μF disc capacitor
1 100 pF disc capacitor
1 680 pF disc capacitor
1 .22μF electrolytic capacitor
2 1μF electrolytic capacitor
1 10μF electrolytic capacitor
2 100μF electrolytic capacitor
Resistors
1 1K ohm (brown-black-red)
1 1.2K ohm (brown-red-red)
1 10K ohm (brown-red-orange)
1 20K ohm (red-yellow-orange)
1 10K ohm potentiometer
1 100K ohm potentiometer
Hardware, Misc.
2 4-turn inductor coils
1 2.7MHz ceramic filter
1 10.7MHz discriminator
1 Rohm™ BA1448S
1 Rohm™ B2611A
1 Rohm™ BA4424N
6
1
2
2
Ramsey Electronics, Inc. FM25A Transmitter Kit
Capacitors
8 .001μF disc capacitors
[C10,C12,C13,C26,C27,C28,C29,C31]
7 .01 μF disc capacitors [C7,C8,C15,C23,C24,C42,C43]
2 .1μF disc capacitors [C9,C16]
2 .022 μF ceramic capacitors [C14,C22]
2 5 pF disc capacitors [C18,C20]
2 10 pF disc capacitors [C30,C32]
2 27 pF disc capacitors [C1,C2]
2 47 pF disc capacitors [C35,C37]
1 75 pF disc capacitors [C36]
1 220 pF disc capacitors [C33]
8 10 μF electrolytic capacitors
[C3,C6,C11,C17,C19,C21,C25,C34]
1 100 μF electrolytic capacitors [C4]
1 1000 μF electrolytic capacitors [C5]
Resistors
1 100 ohms (brown-black-brown) [R12]
2 220 ohms (red-red-brown) [R14,17]
1 270 ohms (red-violet-brown) [R13]
2 470 ohms (yellow-violet-brown) [R2,R10]
1 1K ohms (brown-black-red) [R31]
1 2.2K ohms (red-red-red) [R19,]
2 3.3K ohms (orange-orange-red) [R9,R15]
2 4.7K ohms (yellow-violet-red) [R21,R28,R30]
5 10K ohms (brown-black-orange) [R1,R4,R5,R18,R20]
3 47K ohm (yellow-violet-orange) [R8,R27,R29]
1 100K ohms (brown-black-yellow) [R7]
1 150K ohms (brown-green-yellow) [R22]
1 10M ohms (brown-black-blue) [R3]
2 1K ohms potentiometer [R11,R16]
1 100K ohm potentiometer [R6]
Note: Items included in the Ramsey™ FM25A Kit that are not listed where not used in AFeL
7
(FM25A Kit continued)
Semiconductors
1 2N3904 NPN transistor [Q1]
2 2SC2498 or 2570 NPN transistor [Q2,Q3]
1 Varactor diode, marked MV2105 [D21]
1 LED [D1]
1 Shielded can inductor [L1]
1 Pre-wound spring style inductors [L2,L3]
Hardware, Misc.
1 6MHz crystal, marked 6.00 [Y1]
1 38 KHz crystal [Y2]
1 78L05 +5 volt voltage regulator [VR1]
1 78L02 +2.6 volt voltage regulator [VR2]
1 7812 +12 volt voltage regulator [VR3]
1 18-pin socket for U3
1 145170 Serial PLL IC [U1]
1 BA1404 Stereo modulator IC [U3]
1 FM-25A printed circuit board
1 RCA-style jacks [J2,J3,J4]
1 DC power jack [J1]
1 Horizontal push-button switch [S1]
1 Whip antenna [ANT1]
1 12 volt DC power transformer
1 Two pin jumper and jumper block [JMP1]
8
FM25-A Layout
NOTE: Items Blocked in RED are not part of AFeL, but are part of
Ramsey ™ FM25-A Kit.
9
USB – PIC Schematic
10
FM Receiver Schematic
11
Transmitter Schematic
12
Software List
Visual Basic (User Interface)
First:
Main: main.vbp
PIC 16C745
Main: pic.c
Packages:
usb_main.c
ushb_ch9.as
stub.as
hidclass.as
descript.as
usb_defs.as
13
Visual Basic ‘First’Code
Const
Const
Const
Const
Const
SCAN = 1
TXON = 2
TXOFF = 3
GOOD = 11
BAD = 13
Private Sub cmdAuto_Click()
frmMain.Show
frmFirst.Hide
intMode = SCAN
sngTestFreq = 92.3
ReDim Buffer(2)
Do
sngTestFreq = Round(sngTestFreq + 0.2, 1)
'Sends three bytes to the device and reads two bytes back.
Buffer(0) = Int((sngTestFreq * 10) / 256)
Buffer(1) = Int(sngTestFreq * 10) Mod 256
HIDComm1.WriteTo Buffer, 3
Buffer = HIDComm1.ReadFrom(2)
intModeRtn = Buffer(0)
intCommResult = Buffer(1)
If intModeRtn <> intMode Then
MsgBox "error", vbOKOnly
End If
If (intCommResult = BAD And sngTestFreq >= 107.9) Then
sngTestFreq = 92.1
End If
frmMain.txtFreq.Text = Round(sngTestFreq, 1)
Loop Until (intCommResult = GOOD)
MsgBox "The AFeL is ready to begin broadcasting", vbOKOnly,
"Success"
frmMain.cmdBroadcast.Enabled = True
End Sub
Private Sub cmdOnce_Click()
sngTestFreq = InputBox("What frequency do you want to scan?", _
"Manual Scan", 92.3)
If ((sngTestFreq * 10) Mod 2) <> 1 Then
sngTestFreq = Round(sngTestFreq + 0.1, 1)
End If
If ((sngTestFreq * 100) Mod 10) <> 0 Then
sngTestFreq = Round(sngTestFreq, 1)
End If
If sngTestFreq > 107.9 Or sngTestFreq < 92.3 Then
sngTestFreq = 92.3
14
End If
frmMain.Show
frmFirst.Hide
intMode = SCAN
'Sends three bytes to the device and reads two bytes back.
ReDim Buffer(2)
Buffer(0) = Int(Int(sngTestFreq * 10) / 256)
Buffer(1) = Int(sngTestFreq * 10) Mod 256
HIDComm1.WriteTo Buffer, 2
Buffer = HIDComm1.ReadFrom(2)
intModeRtn = Buffer(0)
intCommResult = Buffer(1)
If intModeRtn = intMode Then
If intCommResult = GOOD Then
frmMain.txtFreq.Text = sngTestFreq
frmMain.cmdBroadcast.Enabled = True
MsgBox "The AFeL is ready to begin broadcasting", vbOKOnly,
"Success"
Else
If intCommResult = BAD Then
MsgBox "Please choose a different frequency", vbOKOnly,
"Unclear Frequency"
Else
MsgBox "error", vbOKOnly
End If
End If
Else
MsgBox "error", vbOKOnly
End If
End Sub
15
Visual Basic ‘Main’Code
Option Explicit
Dim Result As Long
Dim intMode As Byte
Dim intModeRtn As Byte
Dim sngBCFreq As Single
Dim Buffer() As Byte
Dim Buffersize As Long
Dim sngTestFreq As Single
Dim intCommResult As Byte
'Set these to match the values in the device's firmware and INF file.
Const MyVendorID = &H4D8
Const MyProductID = &H1234
Const
Const
Const
Const
Const
SCAN = 1
TXON = 2
TXOFF = 3
GOOD = 11
BAD = 13
Private Sub cmdAutoScan_Click()
intMode = SCAN
sngTestFreq = sngBCFreq
ReDim Buffer(3)
Do
sngTestFreq = Round(sngTestFreq + 0.2, 1)
'Sends three bytes to the device and reads two bytes back.
Buffer(0) = intMode
Buffer(1) = Int(sngTestFreq * 10) / 256
Buffer(2) = Int(sngTestFreq * 10) Mod 256
HIDComm1.WriteTo Buffer, Buffersize
Buffer = HIDComm1.ReadFrom(Buffersize)
intModeRtn = Buffer(0)
intCommResult = Buffer(1)
If intModeRtn <> intMode Then
MsgBox "error", vbOKOnly
End If
If (intCommResult = BAD And sngTestFreq >= 107.9) Then
sngTestFreq = 92.1
End If
frmMain.txtFreq.Text = Round(sngTestFreq, 1)
Loop Until (intCommResult = GOOD)
16
MsgBox "The AFeL is ready to begin broadcasting", vbOKOnly,
"Success"
frmMain.cmdBroadcast.Enabled = True
End Sub
Private Sub cmdBroadcast_Click()
If cmdBroadcast.Caption = "Start Broadcasting" Then
intMode = TXON
sngBCFreq = sngTestFreq
'Sends three bytes to the device and reads two bytes back.
Buffer(0) = intMode
Buffer(1) = Int(sngTestFreq * 10) / 256
Buffer(2) = Int(sngTestFreq * 10) Mod 256
HIDComm1.WriteTo Buffer, 3
Buffer = HIDComm1.ReadFrom(2)
intModeRtn = Buffer(0)
intCommResult = Buffer(1)
If intModeRtn = intMode Then
If intCommResult = GOOD Then
cmdBroadcast.Caption = "Cancel Broadcasting"
cmdChkFreq.Enabled = False
cmdAutoScan.Enabled = False
Else
If intCommResult = BAD Then
MsgBox "error", vbOKOnly
Else
MsgBox "error", vbOKOnly
End If
End If
Else
MsgBox "error", vbOKOnly
End If
Else
intMode = TXOFF
'Sends three bytes to the device and reads two bytes back.
Buffer(0) = intMode
Buffer(1) = Int(sngTestFreq * 10) / 256
Buffer(2) = Int(sngTestFreq * 10) Mod 256
HIDComm1.WriteTo Buffer, 2
Buffer = HIDComm1.ReadFrom(2)
intModeRtn = Buffer(0)
intCommResult = Buffer(1)
If intModeRtn = intMode Then
If intCommResult = GOOD Then
cmdBroadcast.Caption = "Start Broadcasting"
cmdChkFreq.Enabled = True
cmdAutoScan.Enabled = True
17
Else
If intCommResult = BAD Then
MsgBox "error", vbOKOnly
Else
MsgBox "error", vbOKOnly
End If
End If
Else
MsgBox "error", vbOKOnly
End If
End If
End Sub
Private Sub cmdChkFreq_Click()
intMode = SCAN
'Sends three bytes to the device and reads two bytes back.
sngTestFreq = txtFreq.Text
Buffer(0) = intMode
Buffer(1) = Int(sngTestFreq * 10) / 256
Buffer(2) = Int(sngTestFreq * 10) Mod 256
HIDComm1.WriteTo Buffer, 3
Buffer = HIDComm1.ReadFrom(2)
intModeRtn = Buffer(0)
intCommResult = Buffer(1)
If intModeRtn = intMode Then
If intCommResult = GOOD Then
cmdBroadcast.Enabled = True
txtFreq.Text = sngTestFreq
MsgBox "The AFeL is ready to begin broadcasting", vbOKOnly,
"Success"
Else
If intCommResult = BAD Then
MsgBox "Please choose a different frequency", vbOKOnly,
"Unclear Frequency"
Else
MsgBox "error", vbOKOnly
End If
End If
Else
MsgBox "error", vbOKOnly
End If
End Sub
Private Sub cmdDecrement_Click()
txtFreq.Text = Round((CSng(txtFreq.Text) - 0.2), 1)
If (txtFreq.Text < 92.3) Then
txtFreq.Text = 107.9
End If
End Sub
18
Private Sub cmdIncrement_Click()
txtFreq.Text = Round((CSng(txtFreq.Text) + 0.2), 1)
If (txtFreq.Text > 107.9) Then
txtFreq.Text = 92.3
End If
End Sub
Private Sub Form_Load()
ReDim Buffer(3)
frmFirst.Hide
frmMain.Hide
HIDComm1.Connect
cmdBroadcast.Enabled = False
sngBCFreq = GetSetting("AFEL", "STARTUP", "BCFreq", 25)
If sngBCFreq = 25 Then
sngBCFreq = 92.3
frmFirst.Show
Else
frmMain.Show
End If
txtFreq.Text = sngBCFreq
End Sub
Private Sub Form_Unload(Cancel As Integer)
If cmdBroadcast.Caption = "Cancel Broadcasting" Then
Call cmdBroadcast_Click
End If
HIDComm1.Disconnect
HIDComm1.Uninit
SaveSetting "AFEL", "STARTUP", "BCFreq", sngBCFreq
End Sub
Private Sub txtFreq_LostFocus()
cmdChkFreq.Enabled = True
cmdChkFreq.Default = True
cmdBroadcast.Enabled = False
On Error GoTo ErrorHandler
If ((txtFreq.Text * 10) Mod 2) <> 1 Then
txtFreq.Text = Round(CSng(txtFreq.Text) + 0.1, 1)
End If
If ((txtFreq.Text * 100) Mod 10) <> 0 Then
txtFreq.Text = Round(CSng(txtFreq.Text), 1)
End If
sngTestFreq = CSng(txtFreq.Text)
If sngTestFreq > 107.9 Or sngTestFreq < 92.3 Then
Err.Raise (13)
End If
Exit Sub
ErrorHandler:
txtFreq.Text = "92.3"
sngTestFreq = 92.3
19
Resume Next
End Sub
Private Sub txtFreq_Change()
If cmdBroadcast.Enabled = True Then
If cmdBroadcast.Caption = "Cancel Broadcasting" Then
Call cmdBroadcast_Click
cmdBroadcast.Enabled = False
End If
End If
End Sub
20
PIC Code
#include <stdio.h>
#include <stdlib.h>
#include "usb.h"
#include <pic.h>
#define SCAN 1
#define TXON 2
#define TXOFF 3
#define GOOD 11
#define BAD 13
#definePORTBIT(adr, bit)
((unsigned)(&adr)*8+(bit))
static bit
static bit
RXStatus @ PORTBIT(PORTA, 0);
TXStatus @ PORTBIT(PORTA, 1);
static bit
static bit
Done @ PORTBIT(PORTA, 2);
Done1 @ PORTBIT(PORTA, 3);
static bit
static bit
RX @ PORTBIT(PORTB, 0);
TX @ PORTBIT(PORTB, 1);
static bit
static bit
static bit
CE @ PORTBIT(PORTB, 2);
CK @ PORTBIT(PORTB, 3);
DA @ PORTBIT(PORTB, 4);
static bit
static bit
static bit
EN @ PORTBIT(PORTB, 5);
CLK @ PORTBIT(PORTB, 6);
DIN @ PORTBIT(PORTB, 7);
static bit
C_bit @ PORTBIT(STATUS, 0);
unsigned int hibyte;
unsigned int lobyte;
void setup_tx_pll(void)
{
CLK = 0;
DIN = 0;
21
EN =1;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
DIN = 0;
EN = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
DIN = 1;
CLK = 1;
CLK = 0;
DIN = 0;
CLK = 1;
CLK = 0;
EN = 1;
//PLL IS NOW RESET
22
//SETUP C REG
DIN = 0;
EN = 0;
CLK = 1;
CLK = 0;
DIN = 1;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
DIN = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
DIN = 1;
CLK = 1;
CLK = 0;
DIN = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
EN = 1;
//SETUP REF DIVIDER
// 000000000111100
DIN = 0;
EN = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
23
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
DIN = 1;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
DIN = 0;
CLK = 1;
CLK = 0;
CLK = 1;
CLK = 0;
EN = 1;
}
void tune_tx_pll(void)
{
int ctr;
24
CLK = 0;
EN = 0;
C_bit=0;
for (ctr=0;ctr<=7;ctr++)
{
asm("rlf _hibyte,f");
DIN = C_bit;
CLK = 1;
CLK = 0;
}
for(ctr=0;ctr<=7;ctr++)
{
asm("rlf _lobyte,f");
DIN = C_bit;
CLK = 1;
CLK = 0;
}
DIN = 0;
EN = 1;
}
void main()
{
int mode;
TRISA=(0b00000011);
TRISB=(0);
Done1 = 1;
setup_tx_pll();
Done = 1;
hibyte=3;
lobyte=217;
tune_tx_pll();
Done1 = 0;
for(mode=0;mode<=3000;mode++){}
InitUSB();
SoftDetachUSB();
ConfiguredUSB();
25
while(1)
{
Done = 1;
for(mode=0;mode<=3000;mode++){}
Done = 0;
for(mode=0;mode<=3000;mode++){}
}
}
26
Troubleshooting
FCC Rules & Regulations
*Please Refer to this section of Manual
Completed
First check for loose connections between the USB and PC, the USB and
AFeL Box. Also check to make sure DC adapter is plugged in and the AFeL
Box has been turned on.
If the AFeL user interface software is not able to run, check to see what
Operating System is running on the PC. The AFeL program is meant to run
on Windows® 98/95. The AFeL will not run on other systems.
If your standard FM radio is picking up your transmission and what sounds
like interference from another station change your station immediately.
Please refer to FCC Rules & Regulations.
27
FCC Rules & Regulations
Your Rights
According to FCC Rules & Regulations, unlicensed FM broadcasting, used
by the AFeL, do not have any rights over the licensed FM Broadcasting
stations. This means that any interference the AFeL may cause with
licensed FM Broadcasting must be dealt with immediately. This can easily
be done by changing your AFeL FM transmitting station.
Unlicensed FM broadcasting is discussed further in the FCC Rules &
Regulations part 15.
To order your copy of FCC Rules & Regulations part 15, call the US
Government, Superintendent of Documents, at 202.512.1800, or fax at
202.512.2250. To order the correct document, ask for “CFR Title 17: Parts
1 to 199.” The cost is $24.00. Master Card and Visa are accepted.
28
References for Specifications
For Specification Sheets on Microchip™ PIC visit Microchip:
www.microchip.com
For more information on the Ramsey™ FM25-A Kit visit:
www.ramseyelectronics.com
For Specification Sheets on Rohm™ Audio LSIs visit:
www.rohm.com
For Specification Sheets on Murata™ components visit:
www.murata.com
For Specification Sheets on Soshin™ components visit:
www.soshinelec.com
29