Hi All,
I'm trying to setup a simple VI on a myRIO-1900 to use a digital potentiometer as a variable resistor. I have preciously used an SPI dpot with success however I am having issues when switching to an i2C controlled dpot.
Following the datasheet found here ( http://www.analog.com/media/en/technical-documentation/data-sheets/AD5241_5242.pdf ) I have made the following connections.
[1] A1 -> 5V
[2] W1 -> Analog Input
[3] B1 -> DGND
[4] Vdd -> 5V
[5] SHDN -> Vdd (5V)
[6] SCL -> [32] I2C SCL
[7] SDA -> [34] I2C SDA
[7] SDA -> [34] I2C SDA
[8] AD0 -> 0V analog output
[9] AD1 -> 0V analog output
[10] DGND -> DGND
[11] Vss -> DGND
[12-14] -> No connections
When I make these connections and run the following VI with the i2C express VI set to write, I end up reading a constant voltage which does not change with variation of the 8bit vertical point slide input. Furthermore, I am experiencing some chip overheating if the VI runs for too long which shouldn't be occuring.
There are several areas which I think the error may be arising from:
1. Pinout connections outlined above are incorrect.
2. The slave address is incorrect. I am unsure whether I should be sending analog or digital outputs to the AD pins to define the slave address. the datasheet states " Package pin programmable address bits. Must be matched with the logic states at Pin AD1 and Pin AD0." I hav e set both to a logic low (I think) and therefore assume that AD0 and AD1 are 00. So the slave address bit is 01011 then 00 whch is 255. I have also tried setting both to boolean false with a digital output but I expereince the same problems.
3. Incorrect soldering. The chip is a SOIC chip and I have hand soldered it onto an adaptor board (winslow w9502RC) so that I can sit it into my breadboard.
Does anyone have an idea what the problem/s might be?
Cheers,
Ben