These sensor nodes are based on STC12LE5604AD 8051 controller. STC is one of the most popular MCU in China. In this demo I have connected a pair via a simple NRF4L01 breakout board (with and without antenna) with a simple LED-SWITCH program. I’m going to make them available on the shop soon. Possibly they could become the cheapest sensor node available but yes you need to know 8051 programming via either Keil or SDCC.