MCP23017 ADC detail

[fan174]

I want to know how to operate an MCP23017 I'd have a looked at datasheet and source code

https://ww1.microchip.com/downloads/en/devicedoc/20001952c.pdf

device opcode which seems to be being used meaning the slave address.

slave address is shown 0 1 0 0 A2 * A1 * A0 * R/W in datasheet

source code **broken link removed**

I am not familear with c++ and given hardware, I do not understand Why 0x2o is the address of Slave, can somebody tell me reason ?

 

[Pommie]

Try working with any IIC device and you'll start to understand it.

Mike.

 

[rjenkinsgb]

The I2C device address only uses seven bits, then the R/W bit.

Some things show the address left-aligned (as with the register bits in the datasheet), some things show it right-aligned then shift it and add in the R/W bit as part of the I2C subroutines...

The 0x20 address is right-aligned, so the range is 0-127.
When transmitted and the R/W bit added in, it becomes 0x40 or 0x41.

It can be confusing when trying to cross reference addresses and literal data values.