Automatic DCC Controller Project

Revised 12-29-06

  1. Develop a self contained unit that can automatically control up to four DCC equipped engines, starting and stopping them based on their position on a loop of track
  2. Engine operation will be performed by a PIC processor, a 16F88, that is interfaced with the MiniDCC controller
  3. The control PIC will be operated and configured by a hand-held TV remote control set to produce Sony TV codes
  4. Engine position will be sensed by as many as four light sensors that will be connected to the second PIC.
  5. A 4 x 4 keypad that is connected to the MiniDCC controller will be used to manually operate engines
Connecting the MiniDCC to the Control PIC

The control PIC interacts with the MiniDCC controller through the MiniDCC's keypad.  Six pins from the 16F88 will connect to the keypad through a pair of 4066 ICs.   

(Click the image below for higher resolution)

IR Control / Configuration of 16F88 Controller

Because of a limited number of available pins on the 16F88 an infrared TV remote control is being used to change settings on the controller.  The IR signal is received by the PNA4602M.  It is made to react only to IR signals that are modulated at 38 KHz, the frequency used by a typical TV remote control unit.

These signals are decoded in the 16F88 and are used to set variables, accelerate / decelerate engines and to initiate operation of the controller.



The 16F88 controller is programmed using PIC Basic Pro.  The test code for the controller is below.  Note that it is not yet able to sense train position.  It is being used primarily to test the circuit and its components.

4 x 4 Key Pad

I chose to make up my own 4 x 4 keypad matrix from 16 discreet SPST momentary switches - the ones I have chosen are from Electronic Goldmine (part number G1412)

Circuit Board

The circuit board was designed using ExpressPCB's software.  The board has six sections:

  1. Power supply - a 7805 voltage regulator and associated filter capacitors
  2. MiniDCC controller - the circuit is identical to that in the16F628 MiniDCC (click for schematic)
  3. 4 x 4 keypad - a standard matrix that connects to 8 pins on the 16F628 through eight 1 K resistors
  4. MiniBooster - the circuit is identical to that in the MiniDCC (click for schematic)
  5. PIC Controller - a basic 16F88 circuit with ICSP - note that it drives an external LCD controller from
  6. Keypad Interface - the 4066 ICs allow the PIC Controller to directly "press" any of the keys for acceleration and deceleration.  Note that the direction and headlight keys are not connected to the PIC Controller
Circuit Board Photos

This is a view of the MiniDCC LCD (front) and the PIC Controller LCD (back) and the 4 x 4 keypad (left)

Here is the bare board, component side.

This is an overhead view of the component side with most components mounted.  The MiniDCC PIC is upper left, the PIC Control chip is just below it, the IR sensor is in the center, the 18200 is bottom center and the two 4066's are bottom right - the pushbuttons for the keypad are on the other side.

Here is a full view of the keypad side of the board.  The MiniDCC LCD plugs into the header in the upper right.

This is a close-up view of the component side.

A close-up of the 18200 and power supply section.





Only one piece of rework was necessary.  I miswired the connection between pin 14 and the headlight section of the keypad matrix.  The fix is in the two photos below.  One error on a board with all of these components is not too bad!

Test Code (PicBasic Pro)

Include "modedefs.bas"
cmcon=7 'allows you to use pins as digital rather than analog
ansel=0 'allows you to use pins as digital rather than analog
OSCCON = %01100111 'MUST BE USED to set clock speed %01100111 =$67 = 4mhz
Serial_out var PORTA.2
Ser_Speed con 188
rw0 var portb.0
rw1 var portb.1
rw2 var portb.2
rw3 var portb.2
cl10 var portb.4 ' 10
cl11 var portb.5 ' 11
cl00 var portb.6 ' 12
cl01 var portb.7 ' 13
cl30 var portb.0 ' 6
cl31 var portb.1 ' 7
cl20 var portb.2 ' 8
cl21 var portb.3 ' 9

sensor1 var porta.6 '15
sensor2 var porta.7 '16
sensor3 var porta.0 '17
sensor4 var porta.1 '18

IRin var porta.3
led2 var porta.7 'red LED
led var porta.4 'white LED 'pin 3

temp var word
temp2 var word
temp3 var byte
temp4 var byte
temp5 var byte
temp6 var word
temp7 var word
tempbyte var byte
x var byte
xx var byte
Delay var byte
Delay2 var byte
Vwhole var word
Vdecimal var word

zero con 136
one con 128
two con 129
three con 130
four con 131
five con 132
six con 133
seven con 134
eight con 135
nine con 136
channelUP con 144
channelDOWN con 145
volumeUP con 146
volumeDOWN con 147
OK con 148
Menu con 224
ENTER con 139

digit var byte
SpeedStep var word
TempWord var word
TempWord2 var word
value var byte
temp0 var byte
temp1 var word

Train var byte(10)
xxx var byte
delay = 15 'was 35
trisb=0 'all of port b to output to drive keyboard on miniDCC
p_len var byte
steps VAR WORD
trisa = %11001111
Command Var Byte
IRpulse_length var word(13)
train(1)=0 'cl00
train(2)=2 'cl10
train(3)=4 'cl20
train(4)=6 'cl30
Train(5)=1 'cl01
Train(6)=3 'cl11
Train(7)=5 'cl21
Train(8)=7 'cl31
'next line toggles all 4066's to initiate them - NEED IT!
for xx=1 to 8:high train(xx):pause 10:low train(xx):pause 10:next
'pause 200
serout2 serial_out, Ser_Speed,["?f?c0"]:pause 200:serout serial_out,Ser_Speed,["?f?c0"]:pause 200 '?c0 turns cursor off
serout2 serial_out, Ser_Speed,["?B40"]:pause 200 'set brightness of LCD
serout2 serial_out, Ser_Speed,["MiniDCC Driver_test?nd. bodnar 12-2006?nVersion ",#vwhole,".",#Vdecimal]
pause 200

gosub getir:
if command >=128 and command <=137 and command <> 136 and command <> 134 then

if xxx=6 then xxx=7
if xxx=5 then xxx=6
if xxx=4 then xxx=5
if xxx=8 then xxx=4
if xxx=10 then xxx=8

Serout2 serial_out, Ser_Speed,["?y0?x00Cmd= ",#xxx," ",#train(xxx)]
gosub TrainUp:command=0
if command=OK then gosub All_Stop:command=0
if command = enter then goto GetRevSettings
goto start:

for temp=1 to speedstep :high Train(xxx):pause delay:low Train(xxx):pause delay:next temp

for temp=1 to 35
for temp2=5 to 8
high train(temp2):pause delay:low train(temp2):pause delay
next temp2
next temp

low led
Serout2 serial_out, Ser_Speed,["?y3?x00@ IR ",#temp4," "]
Pulsin IRin ,0,IRpulse_length(0)
if IRpulse_length(0) < 200 then 'was 200 for 4 mhz clock
toggle led
for xx=1 to 12
pulsin IRin,0,IRpulse_length(xx)
next xx

if IRpulse_length(1) < p_len then 'was 100 for 4 mhz clock
Command.bit0 = 0
Command.bit0 = 1
if IRpulse_length(2) < p_len then
Command.bit1 = 0
Command.bit1 = 1
if IRpulse_length(3) < p_len then
Command.bit2 = 0
Command.bit2 = 1
if IRpulse_length(4) < p_len then
Command.bit3 = 0
Command.bit3 = 1
if IRpulse_length(5) < p_len then
Command.bit4 = 0
Command.bit4 = 1
if IRpulse_length(6) < p_len then
Command.bit5 = 0
Command.bit5 = 1
if IRpulse_length(7) < p_len then
Command.bit6 = 0
Command.bit6 = 1
if IRpulse_length(8) < p_len then
Command.bit7 = 0
Command.bit7 = 1
If Command.bit7 = 0 then 'Bit 7 is one of the device bits
Command = Command + 1
If Command = 10 then
Command = 0
serout2 serial_out, Ser_Speed,["?y3?x10CMD= ",#command]


high LED:pause 500:low LED
gosub getir
if command=0 then GetRevSettings0
if command > 137 or command < 128 and command <>139 and command <> 0 then
goto start: 'abort on non number 0-9
if command=139 then GetRevSettings0

if Value = 10 then value=0

if value=0 then high LED:pause 250:low LED
for tempbyte=1 to value:High LED:pause 100:low LED:pause 100:next tempbyte

pause 100:command=0
if digit=0 then
temp0= speedstep / 256
write 0, temp0
temp1 = temp0*256
temp2= speedstep-temp1
write 1, temp2
'gosub test4:
goto start:
goto GetRevSettings0

First MiniDCC Built

This is the first unit I built - it uses the MiniDCC board and a home made switch matrix. 

Here is the back of the same unit

This is a close-up of the first screen

This is screen 2


This is a controller I made by rewiring a board from a speedometer that I have designed.  It uses the same type of keypad                




Another shot of the same unit

View of the back of the board.

Another view of the back.