need help with PBP, I2C and MCP23017

[keithv]

It's probably your copy and paste, because it's done it to me before on this forum, but if the code is indeed correct, your ANSEL, ANSELH, TRISC, and TRISA don't look right. It should a % sign letting PBP know that it's binary and it should have 8 bits.

TRISC = %00000000

[richard]

I2CWRITE SDA,SCL,$20,[$05,%10111000]

I had the same setup for Arduino which worked fine.

Arduino use a 7 bit i2c address pbp uses a 8 bit address.
you make no mention of how you have AO,A1,A2 on the expander connected

pbp i2c address = (% 0 1 0 0 A2 A1 A0 )<<1 for a mcp23017

[queenidog]

Address bits are connected to ground. for Arduino I could use address $20 or 0 to access, the latter if I used one of the libraries.

[richard]

for Arduino I could use address $20 or 0 to access, the latter if I used one of the libraries.

in Australia I drive on the other side of the road, its horses for courses
pbp uses 8bit address scheme

Address bits are connected to ground

so A0=0 A1=0 A2=0
plugged into formula
pbp i2c address = (% 0 1 0 0 A2 A1 A0 )<<1
addr =(%0100000)<<1 = $40

so
I2CWRITE SDA,SCL,$40,[$05,%10111000] is whats required

[queenidog]

Thanks Richard. MELabs also told me it was $40 for address. That was the problem! That and the fact my outputs are active low and I was sending active high bits.