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The main problem here is that they both need to communicate via the Arduino's SPI bus, and I know that each of the two devices will need its own CS pin (The data logger is hard wired to 10, so the digital potentiometer will need a different one)

This would be fine, except that the digital potentiometer has one pin for both SPI and SDO. I read that to connect this to the Arduino, the shared pin on the digipot needs to be connected to the MISI pin on the Arduino (pin 12) and then to bridge the MISO pin to the MOSI pin with a resistor.

Would anyone be able to tell if this will work. I do not want to try connecting the two devices like this just in case it breaks something in the board.

Thanks

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I have done the same thing in the past for a DS1302 RTC that uses the same communication system. Yes, it works. Will it interfere with the other communication though? Quite possibly. It works fine for half duplex communication, but could cause interference with something else on the bus that is full duplex.

If in doubt, and you're not worried about high speed or high efficiency (you're not changing the potentiometer's value often) then use three other pins and bit-bang your own half duplex serial interface - it's not hard.

  • Thanks, I'll give it a go, and if it doesn't work, i'll try bit banging with three other pins. speed isn't a problem. I'll let you know how things go – cw1998 Nov 13 '15 at 0:32

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