I2C bus and EmonTX shield v2


I have a 7-segment LED display which just needs a connection to the I2C bus on the Arduino to work. The I2C bus is present on analogue pins 4 and 5 on my Arduino Uno. I've taken a look at the EmonTX v2 shield and it doesn't use ADC5, but it does use ADC4 (for CT4 input). Has anyone had any experience of using the I2C bus with the EmonTX v2 shield? 

I'm wondering whether, if I don't connect a CT to the CT4 input, I can just use ADC4 and ADC5 for the I2C bus instead....

I'm going to get an Arduino prototyping shield to see if I can bring these two pins out and give it a go...


tomkerswill's picture

Re: I2C bus and EmonTX shield v2

Quick updated on this. I did mange to get the 7-segment display working with the emonTX shield. I used a breadboard and disconnected ADC4 from CT4, to use that for the I2C bus.

The 7-segment display functioned at the same time as the emonTX shield v2, but I found that the current readings were not reliable, so perhaps some interference from the LED display, or something else that caused issues. In the end, I abandoned using the LED display, and instead attached an Ethernet shield to the arduino (with emonTX shield v2 above), which allowed me to record readings to emonCMS and display current consumption on a tablet instead. This works really nicely. I'm working on using a nook eReader to display the values in an energy-efficient way.


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