- Fri May 08, 2015 8:10 am
#16892
If you take the resistors (the sum, not the ratio between the resistors, that's fixed of course) to small, it will drain a lot of power (maybe too much) from the source, if you take them too large, the divider will be influenced too much by the impedance of the gpio pin, of which there is no exact data, which may yield a voltage above 3.3V destroying the input.
- Fri May 08, 2015 8:11 am
#16893
OTOH if you take a simple bc547 or similar, they will happily take 50 Volts and 100-500 mA (depending on the type) without breaking.
- Fri May 08, 2015 8:20 am
#16895
Aside from the electrical interface covered above, there is also the issue that GPIO2 suffers the same problem as GPIO0, that if your signal presents LOW to GPIO2 when the ESP powers up *or resets*, it will boot in a mode that will not run your application. If this is a showstopper for you (it has been for me in some cases) on ESP-01, and your application does not need serial I/O, you could use TX or RX instead. (GPIO1/GPIO3).
Cheers,
John
Cheers,
John
- Fri May 08, 2015 8:24 am
#16897
Agreed. I think if you want to go serious stuff, you'd better use an esp where other gpio's are available.
