I2C I/O Expander PCF8574 hanging?

[badrad]

I am trying out the PCF8575 - 16 bit expander in my application. The high byte will be connected to LEDs for output, and the low byte is connected to switches.

For your application using the PCF8574 - did you use the I2CREAD and I2CWRITE commands control the bit expander? Would you mind posting a snippet of your code example on how you control the device?

Thanks.

[NavMicroSystems]

badrad,

for several reasons I have written my own routines that I can't share.

But
I2CWRITE and I2CREAD should work fine.

(Don't forget the 4k7 PullUps on the Data and Clock Lines)

[badrad]

badrad,

for several reasons I have written my own routines that I can't share.

But
I2CWRITE and I2CREAD should work fine.

(Don't forget the 4k7 PullUps on the Data and Clock Lines)

Thanks NAV, no probs with the proprietary stuff, understandable. I changed my pullups to 4k7, i had originally put in 10Ks.

The pcf8575s works like a charm. I have 8 panels with a pcf8575 each on one I2C bus, and another 2 on another bus I2C. Highbyte connected to proximity sensors, and Lowbyte connected to LEDs. There is a 3rd I2C bus for serial eeproms, and one serial port for a serial graphic display (Orbital Matrix).

The tricky part of this equation was all the parts are SMD. So I did not prototype the design to do my trials and testing, just straight from paper to circuit board layout. Hand soldering those SOIC and TSSOP, and 604 size parts is NOT a fun task.

Fun only when it works in the end... Now on to the task of coding the darn thing.