Max Thermistors using imp002?

I apologize for the simple question.

What is the max number of thermistors that can be read by an imp002, assuming I use Tom’s tempbug design which requires one of the I/O pins to drive the thermistors high and low? For example, on the imp001 the answer is 5.

I have been using the imp for thermistor temperature monitoring and have moved on from the imp001 to the imp002. I do equipment diagnostics and honestly, I can never have enough data streams. I’m spending Easter finally documenting what I think would be a good board which is a match to my needs, dedicated to thermistor monitoring using imp002. I’m not great with electronics and I/O capabilities.

Thanks in advance. Happy Easter 2014!

imp002 exposes 2 more ADC pins, but also a few others, so if you dont need a ADC pin to drive them, that would be 3 more thermistors.

If you need more than that, theres ADC chips outthere that can talk with the imp over I2C.
For example MAX127 - http://www.maximintegrated.com/datasheet/index.mvp/id/1890
Thats a 5V chip though, you can probaly find some 3v3 ones too.

Those chips have address lines, usually 2 or 3, so you can add up to 8 of them, each giving 8 ADC channels on one I2C bus, and the imp002 have 2 busses :slight_smile:

Or you can look into onewire sensors, like the DS18B20 these dont need a dedicated line for each sensor, but instead share a single one, so you can have multiple sensors on 1 pin, but they are quite a bit more difficult to interface with.

You could also use an analog mux to get to more of them, but I2C or SPI ADC is good too.