Difference between revisions of "AQC-0-0-0-0"
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The AQC-0-0-0-0 is a CO2 sensor, much like the [[MH-Z19B]]. It has the same form factor and is pin compatible. Regarding the protocol it is only compatible with the MH-Z19 for the commands 0x86 and 0x87. | The AQC-0-0-0-0 is a CO2 sensor, much like the [[MH-Z19B]]. It has the same form factor and is pin compatible. Regarding the protocol it is only compatible with the MH-Z19 for the commands 0x86 and 0x87. | ||
| − | The sensor communicates using TTL serial, 9600 8N1. | + | The sensor communicates using 5V-tolerant 3.3V TTL serial, 9600 8N1. |
Through reverse-engineering a firmware-dump, we've found the following command packet format: | Through reverse-engineering a firmware-dump, we've found the following command packet format: | ||
Revision as of 05:31, 5 January 2021
The AQC-0-0-0-0 is a CO2 sensor, much like the MH-Z19B. It has the same form factor and is pin compatible. Regarding the protocol it is only compatible with the MH-Z19 for the commands 0x86 and 0x87.
The sensor communicates using 5V-tolerant 3.3V TTL serial, 9600 8N1.
Through reverse-engineering a firmware-dump, we've found the following command packet format:
Teardown
Bottom of PCB, as visible without destroying the sensor
Top of PCB (inside)
Case removed
Protocol
- Query: id 01 cc p1 p2 p3 p4 p5 cs
| id | Device BUS id? Is 0xFF for our device, but seems variable. |
| cc | Command (e.g. 0x86) |
| px | Parameters, left at 00 when there are none |
| cs | Checksum |
Commands
0x86 or 0xC5: Request CO2 level
- Parameters: none.
- Response: FF 86 hh ll 00 00 00 00 cs, where the CO2 level is hh * 256 + ll PPM.
- Unlike the MH-Z19B, no other info is returned except the CO2 level in PPM.
0x87: Perform manual calibration immediately
- Parameters: none.
- Response: none.
- Implemented by filling the measurement history with the current value and then letting the regular calibration do its magic.
0xC1: Configure
- With p1 set to 0x13 - 0x22: store 16 bit value in p4/p5 in the specific register. We haven't figured any of these out yet.
- With p1 set to 0x32: commit to flash
- With p1 set to 0xAA and p2 set to 0x00: set operation mode to 0
- With p1 set to 0xAA and p2 set to 0x01: set operation mode to 3
0xC2: Set operation mode to 1
- Parameters: none.
- Response: none.
0xC3: Set operation mode to 2
- Parameters: none.
- Response: none.
0xC4: Dump raw measurement
- Parameters: none.
- Response: 5D 00 00 00 01 v1 v1 v1 v1 v2 v2 v2 v2 v3 v3 v3 v3 cs
- Dumps three 32 bit values, no idea what they are, but we're assuming they're raw sensor values.
0xC5: Same as 0x86
See 0x86.
Operation modes
- 0: Seems to be the same as 3.
- 1: Continuous PPM output on serial as if command 0x86 was given continuously.
- 2: Continuous raw diarrhea mode, keeps sending lots of debug(?) data without checksums.
- 3: Poll mode (default)
Checksum
Same as MH-Z19B.