MH-Z19B
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| Project MH-Z19B | |
|---|---|
| |
| Some research into the MH-Z19B CO2 sensor | |
| Status | Initializing |
| Contact | Disasm |
| Last Update | 2019-10-01 |
Introduction
MH-Z19B is an updated version of the MH-Z19 sensor.
Hardware
- STM32F051K86 MCU
- Unknown analog light+temperature sensor
- Two 3.3V regulators
- 1.5V voltage reference
- Lamp
Teardown
Back side of the MH-Z19B sensor with unlabeled SWD pads on the right:
Front side of the (4-layer) PCB:
Partial schematics:
Firmware
MCU firmware can be easily dumped through SWD pads. Pinout:
| Pin | Signal |
|---|---|
| 1 (square) | 3V3 |
| 2 | GND |
| 3 | SWDIO |
| 4 | SWCLK |
| 5 | RESET (active low) |
Additionally, bootloader asks for a firmware update during the first 20s of startup.