DCC communication between commander and decoder

Hello, All!

I would like to make a very simple DCC system (digital modell railway) with 16F716 commander and 16F716 decoder in engine.

I made electronics succesfully, when I apprehended using of booster, and logic of NMRA standard signal (preamble,0, address,0,instruction,0,error,1); but I don't know, how I get sended signals with decoder?

So; the logical 0 means that You change by booster "direction" of rails (change polarity) at first +/-, wait 58 mikrosec (using by 4 MHz xtal oscillator it means 58 steps), change polarity -/+, wait 58 mikrosec again, and sign is ready. Logical 1 is same, but the waiting time is 100 mikrosec.

I tryed to simulate a signal-sending-routine: made a transmitter PIC and a receiver PIC. Both are same, difference is only that transmitter gives a logical 0 sign, receiver gets it.

I made a short bit-examination (receiver input is RB4):
btfss PORTB,4
goto $-1
wait_40mks
btfss PORTB,4
goto $-1
bsf PORTB,7 (connected LED)

I thought that if I sent a 58 mikrosec long sign (simulated BSF), if the 40 mks delay expired, the input sign 1 yet, that the second bit-trap enables to pass-on. If I put into routine a 100 mikrosec long delay, when it stops, the input sign must be ZERO (it expired before 42 mikrosecs...), the second bit trap must makes a never-ending cycle - BUT NOT !!!!!!!!!! NOT MAKES! WHY??????????????????????????????????

Please help me. What is the problem? What I corrupt? Please help me, If I shall understand it, I shall can make routines for my DCC system.

ThanX forwardly all helps!

fejesg

Would probably be helpful to post your schematic & code.

Hi, Bill!

Thank You the fast reply. So, the asm progs are a bit long... May I send it by attached file? And which format can You check the schematics? Is it enough to attach sch-s&brd-s (by Eagle 5.0.3 freeware), or should I export to png? How is better for You?

fejesg

fejesg said:

Hi, Bill!

Thank You the fast reply. So, the asm progs are a bit long... May I send it by attached file? And which format can You check the schematics? Is it enough to attach sch-s&brd-s (by Eagle 5.0.3 freeware), or should I export to png? How is better for You?

fejesg

Click to expand...

hi,
Attach the program as *.asm and the circuit as *.png

Hi Eric!

Yes, I attach the last version of commander&decoder (I tryed to make circuits with 16F84A, 16F628A and 12F683 - but I stayed with 16F716; because 84A has no extras and needs xtal osc, 628A has many extras (pwm, tx), has intosc_4mhz but has not ADC-s, 683 has pwm, ADC-s, intosc_4mhz, but has only 5 I/O pins, whisc is not enough to handle LCD and DCC ports.... so, if I shall understand progamming devices, I shall make switch-signal-accessory decoder by 12F683)

The attached circuits are working, because I made them on probe-panel.

fejesg

So; because of I shall to make a very simply electronic (for myself, not want to resell), I thought out 2 own varibles, which are in NMRA standard, by free using by amateurs; CV105 and CV106.