Serial communication between PIC and Atmega controileer trough RS485

[visitac]

Hello aratti,

Yes i have the pulldown and the pullup resistors connect, not solve

with this i receive on the display the data on the atmega88 controller that works as slave

_start:

If Ischarwaiting() <> 0 Then 'test if char arrive
Inputbin Serialchar 'get it
If Serialchar <> 254 Then Goto _start 'the first value must be 254
Inputbin , T_destino , Crypt 'get the rest two values
Clear Serialin
End If


the works as master, and send this binary data

i try to send it as decimal as too hex
serout2 disp_pos,396,[dec master,dec destino,dec posicao]
and also
pause 1000
serout2 disp_pos,396,[hex2 master,hex2 destino,hex2 posicao]

unfortunatly without sucess

I have no more idea what can be wrong

Best regards
visitac

[aerostar]

Just a thought, if you have accidently crossed the rs485 wires, then the signal will be inverted at the receiving end, so your serial data would be inverted.

[aratti]

With fragment of code and no schematic, I personally think you cannot get much more help. Please post the whole code you are using, along with some reference to the data sheet of the slaves you have installed in your network. Naturaly complete the info with a schematic on the setup.
With a more complete picture you will have a better chance to get the corrected advice.

Cheers

Al.

[visitac]

Hello aratti,

The network is only one master, the pic controller, on there i use serout2 and a 7segment display as slave, that use a Atmega88P. Both with baud 2400
The display works fine on other project as slave too on baud 38400, all with Atmega controllers. The display is not a problem, the protocol is the same,
only on this project with the pic i have change the baud to 2400. With software uart it not possible to work on baud 38400. Why i have change the baud on the
display to 2400.

I can draw a schematic tomorrow, but like i said the display is working on the other project. On the board with the pic i have connect PORTE.0 to pin 4 and PORTE.2 to pin 1
of the max487. The pin 2 and 3 of the max487 connect together to PORTE.1. On startup make the PORTE.1 as output and high for transmit mode. A is connected to A and B to B of the max487 on the display.

Best regards
visitac