8-bit Microcontrollers中的主题 Re: Problem receiving

Problem receiving

kacto — Sun, 11 May 2008 06:57:05 GMT

I`m sending bytes trough sci to pc, but not receiving what i'm supossed to, can anyone tell me why?

Here is my test code for a gp32. 9600 bd, 1 bit stop, no parity

main: rsp

          mov     #$00,CONFIG2
          mov     #$11,CONFIG1
          nop
        nop
          cli

mov #$20,SCBR ; Baud Rate = 9600

mov #$40,SCC1 ; Enable the SCI peripheral
mov #$0C,SCC2 ; Enable TX and Rx

lda scs1

REP:brclr   7,scs1,*
        mov     'H',scdr
        brclr   7,scs1,*
        mov     'E',scdr
        brclr   7,scs1,*
        mov     'L',scdr
        brclr   7,scs1,*
        mov     'L',scdr
        brclr   7,scs1,*
        mov     'O',scdr
        brclr   7,scs1,*
        jmp     REP

I also tried using "mov #'H',scdr" but din't work neither.

This is what i get on Realterm Software in hex

EC 69 98 2F 09 6C 29 98 2F 2B EC 29 98 6F 09 EC 29 18 2F 09 EC 6B 98 2F
09 4C 29 98 2F 23 EC 29 98 6F 09 EC 29 98 2F 09 EC 29 98 2F 09 F6 8C 65............

This is what appears watching the ascii code

öŒe¥$zŒe¥$zLf¥$zŒe¥ä{Œe$zŒ%¥$zLf¥$zŒe¥Æ{Œe $zŒg¥$zNf¥${Œe¥Æ{Œe)˜/
Œe$zŒe¥$zLf¥$zŒe¥Ä{Œe $zŒg¥$zNf¥${Œe¥Æ{Œe $zŒg¥$zŒe¥${Œe¥$zŒe)˜/)ì)˜o ........

Any help will be good.

Regards

Re: Problem receiving

bigmac — Sun, 11 May 2008 12:58:23 GMT

Hello,

Your code should definitely be modified for immediate addressing mode, i.e. mov #'H',scdr. Your code would otherwise be reading values from various locations in page zero - not what you intend.

If you still have problems after these changes, maybe your bus frequency isn't quite what you have assumed for the SCBR setting.

Regards,

Mac

Re: Problem receiving

Ake — Mon, 12 May 2008 16:16:50 GMT

Hi,

I took your code and tried to to run it on a ICS08GP board.

The baudrate seemed to be too high, so I corrected

mov #$21,SCBR ; Baud Rate = 9600

Then the TE bit was not set. Instead the TCIE bit was set.

I changed that to.

mov #mSCC2_TE,SCC2 ; Enable TX

and now it works!

Regards,

Ake

Re: Problem receiving

peg — Tue, 13 May 2008 05:55:31 GMT

Hi ,
Well you definately need those #'s
If you re-arrange the hex output, you get:

EC 69 98 2F 09
6C 29 98 2F 2B
EC 29 98 6F 09
EC 29 18 2F 09
EC 6B 98 2F 09
4C 29 98 2F 23
EC 29 98 6F 09
EC 29 98 2F 09
EC 29 98 2F 09
F6 8C 65

This is I assume without the #'s
But you can see you are mostly just getting single bit errors.
This would tend to suggest thaat the baudrate is in the ballpark but not close enough.
BTW you are looking for
48 45 4C 4C 4F

Re: Problem receiving

kacto — Tue, 13 May 2008 08:31:09 GMT

I've already fixed it. I miss calculated de baud rate. I asumed it was 9600 but it was 19200 so i corrected that and now is working fine. I used the "#" in my original code, I just changed it to see if that was the problem, but now that i know what was wrong i put it back again. Thanks

Regards

Kacto