RS232 read problem

[marten]

hello,

I've got a pic witch is write configured, and writes a signal (Binairy ' 010111011') over the  RS232  port. The signal is being converted by a maxim232 ic. And i've measured it, it is +/- - 11 V  (logic 1) dc by 1.5  V dc (zero).

But now i'm trying to read (the PIC (16F870) sends continously) the signal during the basic read and write VI. The write function functions good, but the recieve function..... I've got 1 stop bit, none parity bit, and bautrate is 9600....

Now i'v got no idea why he isn't working?? (he gets a recieve time out)

Who can help me?

[Ray.R]

Is it possible to show us the read portion of your code?

[RayFarmer]

hi,

Are you expecting to see a terminate character, if not, switch this off.

regards

Ray Farmer

[marten]

The PIC sends a clear signal between + 9 and -9 Volt DC, with the cable unconnected. When i connect the cable it is the same but, only from 9 to zero or from 0 to -9 Volt DC.

I am using the basic serial write and read VI in labview and only trying to read (sending is working properly)...

I've treid many options with stop bits, but it isn't working...

I really don't have a clue ....

[marten]

I am using the pic 16f876 the labview code is the basic read and write vi and the assembly code is:

RSZEND
 bank1                ;initialize USART
 movlw  h'A2'     ;mastermode, 8bit, Async, LowSpeed
 movwf  TXSTA
 movlw  h'6'        ;9,6 kbaud @ 4mHz
 movwf  SPBRG
 bank0
 movlw  h'80'
 movwf  RCSTA

 GOTO  loopp

loopp
 movlw  b'10111110'
 movwf  TXREG    
 goto  loopp           ; stays in loopp

[Ray.R]

just curious (maybe I missed something)..

how does it exit "loopp"?

[marten]

it doens't..

so it sends the value continously, is that a problem??

[Ray.R]

It might...

At what rate is it filling up the transmit buffer (from the PIC)? 

Does the processor/controller have time to actually send the data while the buffer is being filled?

[marten]

The Pic sends the signal continously, i don't know of the buffer is being filled. But i think he is sending, so the buffer is empty, but  het sends at a bautrate of 9600..

And in this loop he uses 4 instructions is 4us.... so the buffer 9600 bits per seconde, so 1/ (9600/8) = 83,3 us per byte

So the buffer is (I think) full...

But he sends and i am measuring this with the scope..