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I need help with the PCF8574P in my FEZ DOMINO


#1

Hi Guys,

I’m trying reproduce the project in link below with PCF8574P in my FEZ DOMINO, but I’m not succeeding.

http://wiki.tinyclr.com/index.php?title=I2C_Buttonpad

Perhaps the connection between the ports are wrong or even the code in the example of the link may be wrong.

Please help me with this port expander.

thank you


#2

This may be a silly answer, but the schematic for the project does not include the ground and power connections to the chip. Have you included them in your project?


#3

Check the slave address because the regular version starts with the address 0x20. So if you ground the 3 address pins and use 0x20 for the device configuration it should work, all address pins high would be 0x27. The A version starts with 0x38 and will have an A at the end somewhere like AP or AN. They have the same function but use a different address so there can be up to 16 on the same line.