It's very frustrating, I'm working on this the last 4 days straight, no =
solution so far. I'm going to quickly tell you my problem, and tell you =
what I've done to try solving it.

Problem: Very simple: I have a device that sends data through USART at =
38400baud (I've also tested 19200). I need to receive those bytes and do =
something with them. Right now my problem is even simpler, I just want =
to receive them without errors. I've done this with my PIC16F877A (hw =
USART) and with my PIC18F242 and both of them present the same problem, =
they receive bytes, but more than 80% of them are in FERR condition.

What I've tried:
- Different baud speeds (38400, 19200)
- Different microcontrollers (16f877A, 18f242)
- Pooling the serial port
- Using interrupts (that's what I'm using now)
- I thought the problem could be in the connections with my device, then =
I've done a program on the PC to send exactly the same bytes, at the =
same speed, at the same baud rate through serial port, same thing.

I'm using a development board, so in the main loop of the program I'm =
displaying the contents of RCSTA on PORTD (PORTA on 18f242), and I see =
bit 2 (FERR) blinking like crazy. I know that I'm having FEER on 80% of =
the bytes because I'm incrementing a counter everytime the FERR flag =
goes up on the interrupt, and I know how many bytes I send per second...

I'm using mikropascal, here's the code (it's short, I promise)

I'd appreciate your help very much, thanks!

Padu


/////////////////////////////////////////////////////////////////////
program GPSCountMessages;

var
  i: integer;
  s: string[17];
  rx,x: byte;
 =20
procedure interrupt;
begin
 //taking care of overflow
 if TestBit(RCSTA,OERR)=3D1 then
    begin
      ClearBit(RCSTA,CREN);
      SetBit(RCSTA,CREN);
      exit;
    end;
 if TestBit(RCSTA,FERR)=3D1 then
   begin
     x :=3D RCREG;
     inc(i);
   end
 else
   begin
     //right now I'm not doing anything with that, I just want to get my =
bytes clean
     rx :=3D RCREG;
   end;
end;

procedure Setup;
begin
  Usart_init(38400);
  USART_Read;
  INTCON :=3D 0; // all interrupt bits off
  PIR1 :=3D 0; // ..
  PIE1 :=3D 0; // disable all ext. interrupts
  SetBit(PIE1,RCIE);
  SetBit(INTCON,GIE);
  SetBit(INTCON,PEIE);
end;

{main procedure}
begin

  TRISA :=3D 0;
  PORTA :=3D $FF;
  Lcd_Init(PORTB);
  Lcd_Cmd(LCD_CLEAR);
  LCD_Cmd(LCD_CURSOR_OFF);
  LCD_Out(1,1,'FERR msg count');
  Delay_ms(500);
  LCD_Out(2,1,'                ');
  PORTA :=3D 0;
  rx :=3D 0;
  i :=3D 0;
  found :=3D false;
  Setup;
while true do
begin
  PORTA :=3D RCSTA;
  inttostr(i,s);
  LCD_Out(2,1,s);
end;
end.
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