need help with PBP, I2C and MCP23017

[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.