Hi
I am using LM3S6965 to drive PCF8575 using I2C bit banging on GPIO
I can drive outputs correctly but when I try to read inputs, I can read the 1st byte P00-P07 correctly only but the 2nd byte P10-P17 always are red as 0xff regardless of the input on the port.
in order to use port as input I write 0xFF to the pins from 0x10 to 0x17
and to read 1st I write the address and get the ACk from the PCF8575
then I clock 8 clocks on the SCL and read the bits P07 to P00 "this are red correctly"
then signal ACK by pulling the SDA Low while sending one clock
then I clock 8 bits and read the bits P17 to P10 "these bita are always red as 0xFF regardless of the input applied on the pins P10 to P17"
then send NAK by sending one clock while SDA is high
and finally I send the stop bit.
I connect the IO to GND in order to make the input low.
Dose anyone have recommendation to overcome this problem.
Regards
Hossam Alzomor
