thank for your program ! work very well
use portion of your code for S8 and ESP32S2, with Arduino ESP32 Version 2.0.3-RC1

Hello,

In the following sentence, I guess you meant 256, not 265: "The requested value is in byte 3 and 4 (0x03) and (0x88) with low-byte first. so 88 * 265 + 03. .. followed by two byte for CRC."

Other typos:
"There is no standard library aviable"
"lenght"
"the frist"

Cheers,

Hello, I bought an esp 32 and a senseair s8 for a school project and tryied your code. But I only have an error 99 and don't know why. what does it mean exactly ? thank you in advance for your answer.
Eliot

Hello. I try to use your library with the SenseAir S8 sensor. It seems to work fine (The sensor is responding to UART commands), but it returns weird CO2 values:

[1B][0;32mI (24032) Info: ABC-Period 180 [1B][0m
[1B][0;32mI (28032) Info: Firmware: 335 [1B][0m
[1B][0;32mI (32032) Info: Sensor-ID 793 [1B][0m
[1B][0;32mI (36032) Info: Sensor-ID 11344 [1B][0m
Sending data 
Response[0] = fe 
Response[1] = 04 
Response[2] = 02 
Response[3] = 22 
Response[4] = c3 
Response[5] = f5 
Response[6] = d5 
[1B][0;32mI (37082) Receive_TASK: CO2 8899 [1B][0m
Sending data 
Response[0] = fe 
Response[1] = 04 
Response[2] = 02 
Response[3] = 22 
Response[4] = bf 
Response[5] = f4 
Response[6] = 34 
[1B][0;32mI (42082) Receive_TASK: CO2 8895 [1B][0m

The returned values are way above the range of this sensor. From the datasheet, it says that this sensor is capable of measuring 400-2000ppm