Whats going on? serial comm

[Dwayne]

Hello Bob,

Instead of wading through the code, can you write *just* the code to send the data?

When you do so, make sure the sending pin is a I/O pin.
Make sure you assign it with the TRIS register as a Output
Make sure you You turn off all ADC's and Comparators.

If you cannot scope the output on this pin of any data (like the decimal number 1), you are wasting your time with all the other stuff.

When you get a scoped decimal one, then work on the reciever side.

When the above is finished, insert it in your code where it belongs.

MisterE made some EXTREMELY good points... Do not ignore them!


Dwayne

[BobEdge]

I have scoped the output of the transmitter, no problem with that. To test the circuit I have a PIC16F877A transmitting:

pause 500 'make sure receiver has time to boot
let value = 1
loop:
serout portb.7, 1, [value]
pause 100
goto loop

and a PIC 16F870 receiver:

loop:
serin portb.7, 1, [value] 'get input
high led
serout portb.0, 1, [value] 'send to pin to compare waves
low led
goto loop

The led never flashes so its just sat waiting for input which it never sees, though the scope sees a nice clean signal on the input pin.

I have noted all the points Mr E mentioned. I have tried it on lots of pic types, and various pins, I have included "modedefs.bas", I have a 10k resistor from TX pin to gnd, no comparators to worry about.

I am going to try disabling the A/D before receiving data, but cant see this making a difference, since I'm using port B

regards

Bob...

[darkman]

and a PIC 16F870 receiver:

loop:
serin portb.7, 1, [value] 'get input
high led
serout portb.0, 1, [value] 'send to pin to compare waves
'add here PAUSE
low led
'add here PAUSE
goto loop


and try this software for rs 232 commination capture with pc :

http://www.rs232pro.com

[Dwayne]

Hello Bob,


Bob>>loop:
serin portb.7, 1, [value] 'get input
high led
serout portb.0, 1, [value] 'send to pin to compare waves
low led
goto loop

The led never flashes so its just sat waiting for input which it never sees, though the scope sees a nice clean signal on the input pin.
<<

Ok, One thing I see, is that it will only take a very SMALL amount of time to send the data to the output, Thus your LED may be flashing, but too fast.

Can you scope the POrtb.0? and see the data being transmitted? Do not rely on just 1 LED flashing. (which seems you are doing here). It will flash way too fast, and probably look as if it is not flashing at all.

Since you have scoped the transmitter, and have verified it, then the reciever should be almost the same...Try scoping the PORTB.0, and making sure you have data coming out. If not, it is in your receiver... Then I would suggest slowing down your baud rate to 300.

Dwayne

Bob>>I am going to try disabling the A/D before receiving data, but cant see this making a difference, since I'm using port B <<

Will not make any difference if they are not present on POrtb. PortA ususally has all the AD and comparators...

Make sure your TRISB has the proper pins as I/O... according to your example

your input is PORTB.7 and output is PORTB.0

Thus I would (for safety sake)
Portb=%10000000

This assigns POrtb.7 as a input, and all others as outputs.

Dwayne

[BobEdge]

First of all thanks to everyone who replied to my posts. I have now cured the problem

serout serpin, 0, ["A",#VALUE,"AA"]
and
serin serpin, 0, ["A"],#VALUE
worked just fine.

Kind regards

Bob Edge...