Problem with UART SCC2691

Hi all,

I am doing a project with a 8051 and SCC2691
Can any body show me how to use a 8051 to send data to a pc with the SCC2691
I have tried for almost 4 months but I still cannot make it.
here is the simplified schematic

http://www.ee.cuhk.edu.hk/~s017281/schematic6.gif


Thank you

 

Terry,

Find the datasheet of this chip at:

http://www.philipsmcu.com/acrobat/datasheets/SCC2691_2.pdf

First make sure your timing is correct. Especially the bustiming is
important.

Second you have to initialise the chip. Check wether you can write data to
the registers and read back. (Not all registers can be read back. Check the
datasheet.)

Try to send data. A resistor-led combination as sold to check serial lines
is very usefull for it.

petrus

 

Dear Petus,

Thanks for your advices. Do you think that this programme can
initialize the IC ? Please help me as I've tried for a long time.

Thank you very much


#include <sfr51.inc>
;------------------------------------------------
LF EQU 0AH ;Line Feed
CR EQU 0DH ;Carriage Return
;------------------------------------------------
ORG 00H
MOV SP,#60H
;------------------------------------------------
BEGIN: LCALL I_LCD
LCALL Clear_LCD
;------------------------------------------------
CLR P2.1 ;enable read
SETB P2.0 ;disable write
;------------------------------------------------
CLR P2.4 ;A2=0
SETB P2.3 ;A1=1
CLR P2.2 ;A0=0
MOV P1, #00110000B ;CR reset TX
MOV P1, #00100000B ;CR reset RX
MOV P1, #00011010B ;CR reset MR pointer,
disable TX, RX
;------------------------------------------------
CLR P2.4 ;A2=0
CLR P2.3 ;A1=0
CLR P2.2 ;A0=0
MOV P1, #00010011B ;MR1 no parity, 8bits
MOV P1, #00000111B ;MR2 normal, stop bit
length 1
;------------------------------------------------
CLR P2.4 ;A2=0
CLR P2.3 ;A1=0
SETB P2.2 ;A0=1
MOV P1, #10111011B ;CSR 9600 baud
;------------------------------------------------
SETB P2.4 ;A2=1
CLR P2.3 ;A1=0
CLR P2.2 ;A0=0
MOV P1, #10111000B ;ACR 10111---
;------------------------------------------------
CLR P2.4 ;A2=0
SETB P2.3 ;A1=1
CLR P2.2 ;A0=0
MOV P1, #00000101B ;CR enable TX, RX
;------------------------------------------------
CLR P2.4 ;A2=0
SETB P2.3 ;A1=1
SETB P2.2 ;A0=1
;------------------------------------------------
MOV DPTR, #MESS1
;------------------------------------------------
FILL: CLR A
MOVC A, @A+DPTR
CJNE A, #0, L1
RET

L1: MOV P1, A
INC DPTR
;------------------------------------------------
SETB P2.1 ;disable read
CLR P2.0 ;enable write
CLR P2.4 ;A2=0
CLR P2.3 ;A1=0
SETB P2.2 ;A0=1
wait_uart: MOV B, P1
JNB B.2,wait_uart
;------------------------------------------------
;------------------------------------------------
CLR P2.1 ;enable read
SETB P2.0 ;disable write
CLR P2.4 ;A2=0
SETB P2.3 ;A1=1
SETB P2.2 ;A0=1
;------------------------------------------------
SJMP FILL
RET
;------------------------------------------------
MESS1: DB "SCC2691_new_test;",LF,CR,0
;------------------------------------------------
END

 

Terry,

Saw a reply but it was removed from the server before I could open it.
(Newsserver of my provider is really bad, but it's the only
broadbandprovider in this place so I have no choice.)

petrus

 

Hi Terry,

I think you are not using the write and read strobes correctly. If you wish to write, you need to do something like this:

SETB P2.1 ;disable read strobe line
SETB P2.0 ;disable write strobe line

;set destination address for byte 1
CLR P2.4 ;A2=0
SETB P2.3 ;A1=1
CLR P2.2 ;A0=0

MOV P1, #00110000B ;Move byte 1 to P1 register

CLR P2.0 ;enable write strobe
;put delay here to meet write strobe timing requirements
SETB P2.0 ;disable write strobe

;set destination address for byte 2
CLR P2.4 ;A2=0
SETB P2.3 ;A1=1
CLR P2.2 ;A0=1

MOV P1, #00100000B ;Move byte 2 data to P1

CLR P2.0 ;enable write strobe
;put delay here to meet write strobe timing requirements
SETB P2.0 ;disable write strobe

;end of example

Reading is almost the same, except CLR the read strobe, wait a bit, then SET the read strobe, then retreive the data at P1.

The addresses I used in the examples above are probably not correct. I used them as examples only. If I get a chance, I will take a
look at the register setup on the UART.

See if you can redo the code with the new read and write strobe controls and post it here. I'll help ya !^)

Tim

 

hi petrus and tim,

the ic works now.
thank you very much for your kindly help !!



Terry