The article mentions the protocol is very similar to the 1-Wire protocol, and links to the Wikipedia article, which provides some helpful clues: https://en.wiki

The article mentions the protocol is very similar to the 1-Wire protocol, and links to the Wikipedia article, which provides some helpful clues: https://en.wikipedia.org/wiki/1-Wire https://en.wikipedia.org/wiki/1-Wire > To send a binary number "1", the bus master sends a very brief (1–15 μs) low pulse. To send a binary number "0", the master sends a 60 μs low pulse. The falling (negative) edge of the pulse is used to start a monostable multivibrator in the slave device. The multivibrator in the slave reads the data line about 30 μs after the falling edge. The slave's internal timer is an inexpensive analog timer. It has analog tolerances that affect its timing accuracy. Therefore, the pulses are calculated to be within margins. Therefore, the "0" pulses have to be 60 μs long, and the "1" pulses can't be longer than 15 μs. The other “simple” protocols you mention all require a clock line, whereas 1-Wire/IDBUS do not. UART comes closer, except it requires both devices maintain their own independent, reasonably accurate clocks. (How do you tell whether that long high pulse was 4 or 5 1-bits in a row if your clock is terrible?) If you’re trying to design a very simple system that needs to work with wildly inaccurate clocks, you need some kind of self-clocking protocol, like this, where the difference between a 1 and a 0 bit is an order-of-magnitude difference in pulse width. When I was a teen, me and a friend built a device (for a competition) that could encode and decode messages onto a roll of receipt paper by moving the paper across a reader/writer head (a sharpie attached to a servo, and a photosensor) to draw and read lines. Clocking turned out to be by far the hardest problem, because the speed at which the paper moved was too unpredictable and inconsistent (it depended on battery level, inconsistencies in the motor, how heavy the roll was, how hard the marker was making contact with the paper, etc), We spent many hours designing, testing, and tweaking the software and hardware until we arrived at basically this exact encoding scheme — plus a Hamming code based on letter frequency since we were encoding English messages. We felt very proud of this elaborate way to encode text — until we realized we had just reinvented Morse code.