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Topic: I2C digpot on Due (Read 644 times) previous topic - next topic

SlightlyMadScientist

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.

http://ww1.microchip.com/downloads/en/DeviceDoc/22107a.pdf

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?











velon

SlightlyMadScientist friend, I think it's a waste of time trying to work with the ARDUINO DUO (often brick) that have gotten us this IDE. As I have read for less in IPad, dismissed the charge.

It would be nice to be moved these "bricks" with a new version and do not give me that can not be at 5V, because the product is encarecería.

A case not lose more if they continue with this product so darn deplorable.

Really sorry, and I would be more positive, but not lead me to it. Be fair and withdraw the product from the market soon.

Translation by google

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