problem with USART

[leemin]

i encounter some problem when using the hardware USART for communication. pls help. my code as below:

include "modedefs.bas"
DEFINE SHIFT_PAUSEUS 20
define OSC 20
DEFINE SER2_ODD 1

TRISA=%11110000
TRISB= %11111011

symbol Addr_Data_In=porta.4
symbol en=porta.3
symbol stb=porta.2
symbol clk=porta.1
symbol data_out=porta.0

SPBRG = 32 ' Set baud rate to 9600
RCSTA = %10010000 ' Enable serial port and continuous receive
TXSTA = %00100000 ' Enable transmit and asynchronous mode
RCIF VAR PIR1.5 ' Alias RCIF (USART Receive Interrupt Flag)
OERR VAR RCSTA.1 ' Alias OERR (USART Overrun Error Flag)
CREN VAR RCSTA.4 ' Alias CREN (USART Continuous Receive Enable)
LED VAR PORTD.0 ' Alias LED to PORTD.0

ADCON1=6

protocol_2 var byte
protocol var byte
addr var word


mode var byte
Address_Value var word
digit var byte

i var byte

buffer_size CON 35 ' Sets the size of the ring buffer
buffer VAR BYTE[buffer_size] ' Array variable for holding received characters
index_in VAR BYTE ' Pointer - next empty location in buffer
index_out VAR BYTE ' Pointer - location of oldest character in buffer
bufchar VAR BYTE ' Stores the character retrieved from the buffer
errflag VAR BYTE ' Holds error flags

index_in = 0
index_out = 0
i = 0

INTCON = %11000000 ' Enable interrupts
ON INTERRUPT GoTo serialin ' Declare interrupt handler routine
PIE1.5 = 1 ' Enable interrupt on USART

'================================================= ==================================================

main: call display
CALL ending

display: IF errflag Then error ' Handle error if needed
IF index_in = index_out Then display ' loop if nothing in buffer

GoSub getbuf ' Get a character from buffer

protocol=buffer[1]
if (protocol<>"X") then display

addr=buffer[2]
If (addr<>Address_Value) then display

mode=buffer[3]
if (mode=$30) Then Turn_Off_Led

a29=buffer[4]
a28=buffer[5]
a27=buffer[6]
a26=buffer[7]
a25=buffer[8]
a24=buffer[9]
a23=buffer[10]
a22=buffer[11]
a21=buffer[12]
a20=buffer[13]
a19=buffer[14]
a18=buffer[15]
a17=buffer[16]
a16=buffer[17]
a15=buffer[18]
a14=buffer[19]
a13=buffer[20]
a12=buffer[21]
a11=buffer[22]
a10=buffer[23]
a9=buffer[24]
a8=buffer[25]
a7=buffer[26]
a6=buffer[27]
a5=buffer[28]
a4=buffer[29]
a3=buffer[30]
a2=buffer[31]
a1=buffer[32]
a0=buffer[33]

protocol_2=buffer[34]
if (protocol_2<>"Y") then display

lookup a0,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg1=digit
lookup a1,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg2=digit
lookup a2,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg3=digit
lookup a3,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg4=digit
lookup a4,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg5=digit
lookup a5,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg6=digit
lookup a6,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg7=digit
lookup a7,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg8=digit
lookup a8,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg9=digit
lookup a9,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg10=digit
lookup a10,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg11=digit
lookup a11,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg12=digit
lookup a12,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg13=digit
lookup a13,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg14=digit
lookup a14,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg15=digit
lookup a15,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg16=digit
lookup a16,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg17=digit
lookup a17,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg18=digit
lookup a18,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg19=digit
lookup a19,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg20=digit
lookup a20,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg21=digit
lookup a21,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg22=digit
lookup a22,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg23=digit
lookup a23,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg24=digit
lookup a24,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg25=digit
lookup a25,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg26=digit
lookup a26,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg27=digit
lookup a27,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg28=digit
lookup a28,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg29=digit
lookup a29,[$FD,$85,$DB,$9F,$A7,$BE,$FE,$95,$FF,$BF,$80],digit
seg30=digit

shiftout data_out,clk,MSBFIRST,[seg30,seg29,seg28,seg27,seg26,seg25,_
seg24,seg23,seg22,seg21,seg20,seg19,seg18,seg17,_
seg16,seg15,_
seg14,seg13,seg12,seg11,seg10,seg9,_
seg8,seg7,seg6,seg5,seg4,seg3,seg2,seg1]
high stb
pause 5
low stb

goto display


' Subroutines

Disable ' Don't check for interrupts in this section

getbuf: ' move the next character in buffer to bufchar
index_out = (index_out + 1) ' Increment index_out pointer (0 to 63)
IF index_out > (buffer_size-1) Then index_out = 0 ' Reset pointer if outside of buffer
bufchar = buffer[index_out] ' Read buffer location
Return


error: ' Display error message if buffer has overrun
errflag = 0 ' Reset the error flag
CREN = 0 ' Disable continuous receive to clear overrun flag
CREN = 1 ' Enable continuous receive
GoTo display ' Carry on


serialin: ' Buffer the character received
IF OERR Then usart_error ' Check for USART errors
index_in = (index_in + 1) ' Increment index_in pointer (0 to 63)
IF index_in > (buffer_size-1) Then index_in = 0 'Reset pointer if outside of buffer
IF index_in = index_out Then buffer_error ' Check for buffer overrun
HSerin [buffer[index_in]] ' Read USART and store character to next empty location
IF RCIF Then serialin ' Check for another character while we're here


Resume ' Return to program

buffer_error:
errflag.1 = 1 ' Set the error flag for software
' Move pointer back to avoid corrupting the buffer. MIN insures that it ends up within the buffer.
index_in = (index_in - 1) MIN (buffer_size - 1)
HSerin [buffer[index_in]] ' Overwrite the last character stored (resets the interrupt flag)
usart_error:
errflag.0 = 1 ' Set the error flag for hardware

Resume ' Return to program


ending: END

[mister_e]

This thread should give you some tips

Care about the Enable and Disable placement

[leemin]

yupe. i got it d. no problem d. thanks ya.

[sakthi]

hi
i saw ur coding.i m also doing the same thing.i program is to transmit a string from one pic and receiving the same string in the another pic(USART comm) and displaying the received string in the lcd. my transmit program is working well(got the string in hyper terminal).i have the problem in receiving the string,it s not working.i m using 16f877a and micro c complier.seperately my lcd prgm is also working well
my code is

void receive()
{
int i=0;
char s[10];
STATUS.f5=0;
STATUS.f6=0;
for(i=0;i<5;i++)
{
while(PIR1.f5==0)
{}
s[i]=RCREG;
PIR1.f5=0;
}
init_lcd();
display();
}
void main()
{
STATUS.f6=0;
STATUS.f5=1;
TRISC=0;
PORTC=0;
STATUS.f5=0;
RCSTA=0x90;
SPBRG=0x20;
receive();
while(1)
{}
}

if u find any wrong in my code plz help me to correct it

-Sakthi

[mister_e]

OK you're using C language but here we use Melabs PICBasic but anyways, let's try to help you on that.

your problem is with this line

TRISC=0;

Sure if the RX pin is set as an output, it won't work. Just change it and i suspect it will work. but i didn't look the whole thing so i could have miss something.

Good luck!