Arduino breadboard
Before I have built a sensor on a PCB, the Smartmeter IR signal was read with an Arduino and a phototransistor. The schematic is very simple needs only one transistor, a resistor and the phototransistor to work. The Arduino operates purely as a USB to UART bridge and is held in constant reset (no firmware required). The optional LED indicates when a datagram is received. For the phototransistor I used a SFH309 from Osram, which is sensitive in the IR range of the meter IR port and blocks the ambient light. A long flat ribbon cable allows placing the IR sensor on top of the meter IR port.
