Please check out the full repository on Github for more information!

Currently only my leftover boards are sold. Should there be any interest, I will happily stock more!

What is it?

This is a logic level impulse to S0 converter/interface board. It is used to convert 5v logic level impulses to an S0 compatible format to use sensors like the TCRT5000 reflective optical sensor in existing smart home systems, that usually use 12v or 24v levels for digital inputs. This can be used to read out old school electrical meters as well as modern smart meters that only offer optical IR impulses or a spinning disc to "display" the current power usage.

Why did you make it?

To read out existing electrical meters, offering only an LED for "actual power" output to my smart home system, accepting only S0 compatible inputs.

What makes it special?

Using a low power ATtiny microcontroller the device can not only convert any kind of logic level input pulse to S0 compatible pulses, but it can also count input edges and output pulses only after a set amount of inputs, effectively diving your input frequency. It can detect rising or falling edges, and output HIGH or LOW pulses of your chosen duration. The smallest detectable input pulse is about 150 ns, while the output needs only about 100 µs to fully switch on, so output pulses of about 250µs are viable (though not really supported by most smart home systems) The PCB has multiple jumpers on board to set different input or output configurations, as well as different firmwares supplied in the repository for different pulse detection/output configs. The devices will be shipped with the 01_010_n_r firmware installed, but using the ICSP header any of the firmware versions can be installed.

My particular system outputs 10,000 impulses of 7ms per kWh, which is too quick for my smart home system. Using the 10_030_i_r firmware version it counts 10 input edges before outputting a single 30ms output pulse of 24 V, which my smart home system can read easily.

In the repository you will also find 3d printable parts to mount the device in your electrical cabinet on DIN rails, as well as a TCRT5000 header fitting German EMH electrical meters.

Please check out the full repository on Github for more information!