Bit-Bang I2C - PIC18F

[john cutler]

I'm trying to ascertain if and how one needs to set the tris register for the scl and sda pins when using CCS bit-bang I2C routines. I did make the necessary pins (A0 and A1) digital via the ADCON1 register. Do I need to set the TRIS or do the CCS routines do it for me? I'm also using the built in USART for RS-232 and wonder if that's a problem.

PIC18F1320, 40Mhz, PCWH 3.163 (and I tried 3.167 also)

Anyone know if/what I'm doing wrong?
Thanks.

John

Here's sample code:

#fuses H4, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
#use Delay(Clock=40000000)
#use RS232(baud=19200, bits=8, BRGH1OK, xmit=PIN_B1, rcv=PIN_B4, PARITY=N)

#use i2c(master, scl=PIN_A0, sda=PIN_A1)


#asm
bsf adcon1,0
bsf adcon1,1
#endasm

.......

i2c_start();
i2c_write(0x40);
i2c_write(255);
i2c_stop();

.....

i2c_start();
i2c_write(0x41);
readtemp = i2c_read();
i2c_stop();



___________________________
This message was ported from CCS's old forum
Original Post ID: 144515797

[Kenny]

:=I'm trying to ascertain if and how one needs to set the tris register for the scl and sda pins when using CCS bit-bang I2C routines. I did make the necessary pins (A0 and A1) digital via the ADCON1 register. Do I need to set the TRIS or do the CCS routines do it for me? I'm also using the built in USART for RS-232 and wonder if that's a problem.
:=
:=PIC18F1320, 40Mhz, PCWH 3.163 (and I tried 3.167 also)
:=
:=Anyone know if/what I'm doing wrong?
:=Thanks.
:=
:=John
:=
:=Here's sample code:
:=
:=#fuses H4, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
:=#use Delay(Clock=40000000)
:=#use RS232(baud=19200, bits=8, BRGH1OK, xmit=PIN_B1, rcv=PIN_B4, PARITY=N)
:=
:=#use i2c(master, scl=PIN_A0, sda=PIN_A1)
:=
:=
:=#asm
:=bsf adcon1,0
:=bsf adcon1,1
:=#endasm
:=
:=.......
:=
:=i2c_start();
:=i2c_write(0x40);
:=i2c_write(255);
:=i2c_stop();
:=
:=.....
:=
:=i2c_start();
:=i2c_write(0x41);
:=readtemp = i2c_read();
:=i2c_stop();
:=
:=
:=

John,
Haven't actually done it, but I think you only need to float the lines.

output_float(PIN_A0);
output_float(PIN_A1);

Also, I think that
readtemp = i2c_read();
should be
readtemp = i2c_read(0);
because the first byte is also the last and need to NACK it.

Regards
Kenny
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515798