Can anyone confirm for me the serial voltage level used at the programming header please?
I am just starting out with this, connecting an emonTx V3 to a Raspberry Pi base via direct serial comms rather than a radio module. As far as I can make out both sides are using 3.3V, I know the Pi definitely is, the RFu328 is run at 3.3V, so I guess it is safe to connect the 2 devices directly?
If someone could confirm the voltage, point me to the information, or otherwise suggest why a direct, unbuffered connection might be a bad idea I would appreciate the help, thanks.
Re: emonTx V3 serial voltage level
update, for anyone else, it works:
as far as I could make out from the schematics at http://solderpad.com/openenergymon/emontxv3/the 5V line only goes to the programming header and to the pulse-counting screw terminal connections. Measured with a multimeter, the voltage on the Tx pin on the emonTx also seemed to stay at 3.3V while not transmitting. So I went ahead and connected the FTDI header on the emonTx to the Raspberry Pi Tx, Rx & GND. It all seems to work quite happily, no level conversion required.