Okay, I think it is still cheaper to buy a dedicated sensor.tlfong01 wrote: ↑Sat Sep 15, 2018 5:23 am
DHT22 directly interrupting Rpi, bypassing stupid and slow MCP23017
Well, I actually have bought three other types of sensors to mess around (the most recent one is DHT12 which is similar to DHT22, but also I2C compatible).
But I really need this time wasting, trouble making, DHT22 for two reasons:
- 1. I need to have 64 sensors for my small, 64 bed room castle (well, in the air) automation project.
Now I am thinking of overcoming the slow and stupid MCP23017 interrupt thing by forgetting it altogether. Instead of using MCP23017 INTA, INTB, I will let DHT22 open drain output (already at the same time, connected to MCPO23017 GPIO pin) to itself directly interrupting RPi.
- 2. I need to show off that I can interrupt Rpi with 64 devices.
Appendix - DHT12
Castle in the air - Don McLean - 2,295,059 views
However, this will not work. Because when you sent a start plus. All the sensor are going to response to you. If you make a dedicated line for the sensors to your Rpi. I think it's a better idea to multiplex them on that single line. So, that you can talk directly to the sensor. You can buy dedicated multiplex chips. Remember that it's need to be bidirectional, or use a trick. An other options is to use a analog switch to enable one sensor on your data bus.