Automation, sensing and robotics • Re: Gas Sensor MQ-7 Arduino and Raspberry Pi Hardware schematic

if i have 1 sensor is useless to use a MCP3008 like that

Yes. You could use an MCP3002 (2 channel) instead of the MCP3008. He probably used an MCP3008 as they are very common/cheap.

Case2B as the gas sensor AD output can be up to 5V, we use a voltage divider (two resistors) so that no more than 3V3 is seen by the MCP3008 (which is running at 3V3).

OMG I just notice that I had a wrong pinout reference. The 4th pin is ANALOG.
Everything makes sense now.

Sorry guys

Can you tell me if:
- is possible to feed the level shifter with analog signal as done in the scheme?

We agreed that voltage divider method is the best for analog signal but... why this guy use a level shifter? Why does he succed??


- is ever possible to feed a MCP3008 with digital signal?
I think not since a digital signal is read as analog 0V (low state) and analog 5V (high state). Like the sensor is giving lowest value and higher value only. If is a % sensor I expect to see a fast switching (digital signal freq) between the two values of 0 and 100%.

Thanks

Statistics: Posted by Gebrey — Fri Jul 19, 2024 6:26 pm

---