June 22, 2026

The Dallas 1-wire protocol saga -- introduction

I plan to work with two devices. One is the DS18B20 temperature sensor. The other is the DS1499L non-volatile memory.

DS18B20

The DS18B20 is a 3 wire device. I bought (on Amazon) back in 2021, a 5-pack of "Hiletgo" branded temperature sensors. These consist of a 2 inch long metal tube which protects the temperature sensor and about 3 feet of ordinary looking black cable. The end of the cable has 3 wires: red, black, and yellow.

They suggest a 4.7K pullup resistor to Vcc, which is the normal expectation for a 1-wire device.

I still see these on Amazon, the 5 pack sells for $11. They give a temperature rating from -55C to 125C. So these might withstand boiling water.

DS1499L

These things look like gigantic coin cells. Inside is a battery and a ram/clock chip. They claim a 10 year lifetime, but these are no longer in production which poses a serious problem for anyone with equipment containing one of these.

MAX31850

These are 1-wire interfaces including an ADC that you can connect to thermocouples. I have a couple of these, so they will offer another way to test a 1-wire driver.

Have any comments? Questions? Drop me a line!

Tom's software pages / tom@mmto.org