OpenEnergyMonitor Community

Emontx V2.2 Not connecting

Hi, I’ve acquired an unused Emontx V2.2 board and components. I’m a newbie to both soldering electronics and very rusty when it comes to programming, so please bear with me here.
I’ve followed the instructions and have soldered all of the components to the board, but when connecting to my pc (using the USB to TTL connector supplied) to upload the firmware, the PC isn’t recognising anything as being connected.
I think I’ve matched the right connectors from the USB to the FTDI pins on the board, but as the pins aren’t labelled on the board, could someone let me know the correct sequencing of the pins?
The solders look “ok”, and having checked the voltage across a number of connections, I’m getting the voltage expected. Is there any other tips or tricks to check the solders or diagnose what’s gone wrong?

Welcome, Rob, to OEM.

Take a look at the FAQ page, many common problems are listed there.

You can find the full circuit diagram and PCB layout in the Wiki: GitHub - openenergymonitor/emontx2: emonTx V2 (through-hole design): A low power, wireless energy monitoring node based on Arduino / JeeNode the files are Eagle CAD (free).

There might also be some helpful information in ‘Learn’ regarding the programmer.

The bit you’re interested in:

  1. GND is nearest the USB.
  2. N/C
  3. 5 V
  4. Rx (really - see below but later labelled Tx)
  5. Tx (really - see below but later labelled Rx)
  6. Reset - needed for programming (from RTS on the programmer)

A “Shop” programmer should plug in directly - no swapped wires.

Beware: Later emonTx’s have the Rx and Tx swapped, for some reason I’ve never managed to work out. The Rx pin on the emonTx is looking for the Rx pin on the programmer, and is therefore the pin that transmits the data, likewise the Tx pin on the emonTx is looking for incoming data that has been transmitted from the Tx pin on the programmer.