software uart - Electronic Circuits Projects Diagrams Free

baftab · 8th October 2007, 12:49 PM

i got this code from a site, but i cant assemble it in keil
which assembler whould i use??
or is there some fault with the code itself??
the '*' are giving some problem

"djnz r1,*" for instance

TXD EQU P1.0 Transmit on this pin
RXD EQU P1.1 Receive on this pin
* The serial baud rate is determined by the processor crystal, and
* this constant which is calculated as: (((crystal/baud)/12) - 5) / 2
BITTIM EQU 45 (((11059200/9600)/12) - 5) / 2
*
* Transmit character in A via TXD line
*
putc CLR TXD Drop line for start bit
MOV R0,#BITTIM Wait full bit-time
DJNZ R0,* For START bit
MOV R1,#8 Send 8 bits
putc1 RRC A Move next bit into carry
MOV TXD,C Write next bit
MOV R0,#BITTIM Wait full bit-time
DJNZ R0,* For DATA bit
DJNZ R1,putc1 write 8 bits
SETB TXD Set line high
RRC A Restore ACC contents
MOV R0,#BITTIM Wait full bit-time
DJNZ R0,* For STOP bit
RET
*
* Receive a character from the RXD line and return in A
*
getc JB RXD,* Wait for start bit
MOV R0,#BITTIM/2 Wait 1/2 bit-time
DJNZ R0,* To sample in middle
JB RXD,getc Insure valid
MOV R1,#8 Read 8 bits
getc1 MOV R0,#BITTIM Wait full bit-time
DJNZ R0,* For DATA bit
MOV C,RXD Read bit
RRC A Shift it into ACC
DJNZ R1,getc1 read 8 bits
RET go home

is this workable??

ikalogic · 8th October 2007, 01:27 PM

I Suppose this code is for a 8051 Micro controller, right?

a simple question, why don't you use the hardware UART.. ?

**Nigel Goodwin** · 8th October 2007, 01:31 PM

Quote:

Originally Posted by ikalogic

I Suppose this code is for a 8051 Micro controller, right?

a simple question, why don't you use the hardware UART.. ?

Go to the back of the class!

You've not being paying attention, he has another thread asking about dual UART's.

baftab · 8th October 2007, 01:51 PM

the hardware uart is already being used
am interfacing a rfid reader and my pc to the controller

i need an extra serial port...
i knw there are controllers available with 2 uarts, but i cant find them here...in my city...

so..?? which assembler should i use???

i think
djnz r1,*

means as long as r1 is not zero, keep on looping??
right??

keil assembler is not assembling

NOW Nigel...some help??

**Nigel Goodwin** · 8th October 2007, 01:57 PM

Quote:

Originally Posted by baftab

NOW Nigel...some help??

Only on a PIC I'm afraid, but my tutorial does describe how it works?
http://www.winpicprog.co.uk/pic_tutorial7.htm

baftab · 8th October 2007, 02:03 PM

there has to be someone on this site...good in 89c51 assemble

??

wake up ppl...help me out!!!

**Nigel Goodwin** · 8th October 2007, 02:11 PM

Quote:

Originally Posted by baftab

there has to be someone on this site...good in 89c51 assemble

It's so old they are probably all dead!

It only seems to be used out India/Pakistan way?.

baftab · 8th October 2007, 02:44 PM

lol yeh...or they might be afraid to come out and show that they know something abt 89c51...they'll be ridiculed at

yeh...am not sure abt india, but in pakistan latest ics are not available..somethin to do with import restrictions on electronics equipments

we get the used ones and old ones :s

i couldnt find a single controller with 2 uarts here :S
no fair!!!

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8th October 2007, 12:49 PM	(permalink)
baftab	software uart i got this code from a site, but i cant assemble it in keil which assembler whould i use?? or is there some fault with the code itself?? the '' are giving some problem "djnz r1," for instance TXD EQU P1.0 Transmit on this pin RXD EQU P1.1 Receive on this pin * The serial baud rate is determined by the processor crystal, and * this constant which is calculated as: (((crystal/baud)/12) - 5) / 2 BITTIM EQU 45 (((11059200/9600)/12) - 5) / 2 * * Transmit character in A via TXD line * putc CLR TXD Drop line for start bit MOV R0,#BITTIM Wait full bit-time DJNZ R0,* For START bit MOV R1,#8 Send 8 bits putc1 RRC A Move next bit into carry MOV TXD,C Write next bit MOV R0,#BITTIM Wait full bit-time DJNZ R0,* For DATA bit DJNZ R1,putc1 write 8 bits SETB TXD Set line high RRC A Restore ACC contents MOV R0,#BITTIM Wait full bit-time DJNZ R0,* For STOP bit RET * * Receive a character from the RXD line and return in A * getc JB RXD,* Wait for start bit MOV R0,#BITTIM/2 Wait 1/2 bit-time DJNZ R0,* To sample in middle JB RXD,getc Insure valid MOV R1,#8 Read 8 bits getc1 MOV R0,#BITTIM Wait full bit-time DJNZ R0,* For DATA bit MOV C,RXD Read bit RRC A Shift it into ACC DJNZ R1,getc1 read 8 bits RET go home is this workable??

8th October 2007, 01:27 PM	(permalink)
ikalogic	I Suppose this code is for a 8051 Micro controller, right? a simple question, why don't you use the hardware UART.. ? __________________ Ibrahim Kamal check my electronics and robotics page: http://www.ikalogic.com/

8th October 2007, 01:51 PM	(permalink)
baftab	the hardware uart is already being used am interfacing a rfid reader and my pc to the controller i need an extra serial port... i knw there are controllers available with 2 uarts, but i cant find them here...in my city... so..?? which assembler should i use??? i think djnz r1,* means as long as r1 is not zero, keep on looping?? right?? keil assembler is not assembling NOW Nigel...some help??

8th October 2007, 02:03 PM	(permalink)
baftab	there has to be someone on this site...good in 89c51 assemble ?? wake up ppl...help me out!!!

8th October 2007, 02:44 PM	(permalink)
baftab	lol yeh...or they might be afraid to come out and show that they know something abt 89c51...they'll be ridiculed at yeh...am not sure abt india, but in pakistan latest ics are not available..somethin to do with import restrictions on electronics equipments we get the used ones and old ones :s i couldnt find a single controller with 2 uarts here :S no fair!!!