need help 89c51 serial communication

[starlet]

89c51 uart source

hi friends

i have a problem in serial communication with at89c51. i want to send 8 bits of data 0-255, i first used serial mode 1 which works well 1-255 but for zero i used mode 3 (9 bit uart) but it caused a problem.
i am using odd parity in PC. and with 8 bits, 9600 baud rate, 11.0592MHZ in uc.

mov a,#161 (161 constant can be variable r0 )
mov c,p
cpl c ;for odd parity
mov tb8,c
mov sbuf,a

but still it works for 7 bits data <128 but it sometimes receives or some times not. i am confused
is there any problem in code? i am using visual basic, but i also tried Hyper terminal but when i transmitted 161 decimal it gives me 237 and many errors fomr >127 values.
need help. but please as soon as possible. i really need to know bug?

 

[PaulHolland]

89c51 serial communication

Hi,

Why using parity if the mcu does not support parity !. You should use the PC in 9600 N81 (9600 Bits/s No parity 8 data bits and 1 stop bit.

use the 8 bit mode on your mcu and set the buadrate gen correct.
send a byte and check before you put a new byte in the send register if its empty...

that is all..

Paul.

 

[starlet]

visual basic 9 bits serial

ok now

9600,N,8,1 works well with MCU for 0-255 but PC was not determinig the two 0s value.
hyper terminal is still showing the black rightward sign for 2 consecative zeros but VB does not show anyone therefore VB is right (null showing) but buffer count increases which is clear that some is receiving.
i was checking hyperterminal. 0 is null char. but 2 zeros are making sign given in picture below (rightward black sign).
that was confusing me to go on parity communication. but it might be the only one case to show 2 null char by that sign which come only for consec. zeros not any other time like for 0 and 1, or 0 and non zero value.

also PaulHolland , parity check communication is supported on at89c51 using TB8 and RB8 bits in 9 bits UART mode. i just missed to check the Parity flag, if i change that then that communication will also be good as other on MCU at89c51.

 

[PaulHolland]

9 bit serial communications with vb

Hi Starlet,

I know you can use the mcu in 9 bit mode and make the 8th bit your parity bit but why would you >??.. its not giving any protection better use CRC instead... btw: you know how to calculate parity quickly on an 8 bit word ???..

regards,

Paul.

 

[ramaswamy1]

89c51 communication 10 bit

i am using 89c51want to communicate to pc with data 8 bit , parity bit even , stop bit 1 . Have any body tried using mode 3 , if yes can you send the source code please.

Added after 6 minutes:

ok now

9600,N,8,1 works well with MCU for 0-255 but PC was not determinig the two 0s value.
hyper terminal is still showing the black rightward sign for 2 consecative zeros but VB does not show anyone therefore VB is right (null showing) but buffer count increases which is clear that some is receiving.
i was checking hyperterminal. 0 is null char. but 2 zeros are making sign given in picture below (rightward black sign).
that was confusing me to go on parity communication. but it might be the only one case to show 2 null char by that sign which come only for consec. zeros not any other time like for 0 and 1, or 0 and non zero value.

also PaulHolland , parity check communication is supported on at89c51 using TB8 and RB8 bits in 9 bits UART mode. i just missed to check the Parity flag, if i change that then that communication will also be good as other on MCU at89c51.

hello . can you send the source code for parity check commincation- please

 

[ctownsend]

why are you using hyperterminal?

You need a terminal program that displays the data in hex. AvrTerm.exe is very good for debugging micro to terminal applications.

look in this thread:



I also posted some simple uart source there.

Good Luck