First of all, I'd like to thank admin for helping me to register (turns out it was a problem with IE :0)
I am currently working on a project where I'd like to use a two digital potentiometers. I just bought an Arduino and don't have much experience with microcontrollers (unless you count a "hello world" LCD project on a PIC about 15 years ago). However, I am reasonably good with analog electronics (I know how to use an op-amp) and have a fair bit of experience with programming. I am also good at electrical measurements (part of my job). Hence, I thought this should be straightforward....
I trying to use a 10K potentiometer controlled via I2C (using the wire lib), a microchip MCP45X1 which looked like a good "generic" pot.
However, I can't communicate with it. I've tried a program I found in a tutorial http://tronixstuff.wordpress.com/2010/10/20/tutorial-arduino-and-the-i2c-bus/
(yes, I know it is not exactly the same part, but as far as I can tell the I2C address and the commands are the same. )
I've also tried the I2Cscanner program, it can't find a device...
I am powering the pot from the 3.3V output on the Due (which-as far as I can tell from the datasheet for the MCP45X1 should be fine for the I2C communication). I am using SDA and SCL on pins 20 and 21 on the Due.
I've mounted the MCP45X1 on an MSOP adapter (soldered under a microscope with a good soldering station, I am doing this at work)
So far I've *Tried with/without external 4K7 pullup resistors. *Tried pulling the hardware address pin (A0) on the MCP45X1 both high and low. *Checked the connections a number of times (beeped it with a multimeter etc). I've also checked that the MCP45X1 has 3.3V between Vdd and Vss. *Tried two different chips just in case I managed to burn the first one.
I've had zero luck so far.
Does anyone have ideas of what else I can try? Have I misunderstood the datasheet of the MCP45X1? It should work with 3.3V, shouldn't it?