Hey, Just wondering if its possible to have more than 3 CT's connected to the emonTX, are there additional analog input to extend this capability?
Basically I want to monitor many circuits in a building and try to get as many as possible connected on one board.
Thanks
Re: More than 3 CT's on emonTX
ADC 4 and 5 are free, see for yourself: http://openenergymonitor.org/emon/emontx/reference%20.
Yes you could build the energy monitor circuit on a bread/strip board and wire it into those free ports.
Re: More than 3 CT's on emonTX
Adding another two Analog channels to be sampled would reduce the accuracy right?
Re: More than 3 CT's on emonTX
Not at all, the Atmega328 on the emonTx spends most of its time sleeping. It would just sample each channel in turn at the same accuracy, and spend less time sleeping. Sampling one channel takes 332ms. Sampling 5 channels would take 1.67s + a bit more overhead for RF transmitting.
There is some info about this in the emonTx design notes: http://openenergymonitor.org/emon/modules/emontx/designnotes
Re: More than 3 CT's on emonTX
Okay Awesome! where on the pcb is the PWR/SER/12C pins. Is it the one below the emonTC sign (under the 2 blue capacitors and above the FTDI pins?)
Re: More than 3 CT's on emonTX
Yes, ADC4 is marked SDA and ADC5 is marked SCK. Their located just below the crystal and the two 2pF de-coupling capacitors.
Re: More than 3 CT's on emonTX
Couldn't find where I read that before, but I remember seeing somewhere that if you sample one channel, the time between measurements is very short (depends on the frequency at which you power the Atmega) and with each channel you add to be measured, the time between two measurements for each of the channels will get longer with each added channel. That's what I meant.