Hello all,
I try to configure a MCP23017 with address 0x27 by setting all the adress pins to 1 and it drives me crazy.
I managed to configure adresses from 0x20 to 0x26 but with 0x27 it fails.
When the MCP is powered with +5V the i2c scan detects nothing :
[00:25:10][I][i2c.arduino:054]: Results from i2c bus scan:
[00:25:10][I][i2c.arduino:056]: Found no i2c devices!
When the MCP is powered with 3,3V the i2c scan detects the MCP but can’t initialize the component :
[00:13:23][C][mcp23017:010]: Setting up MCP23017...
[00:13:23][E][component:112]: Component mcp23xxx_base was marked as failed.
...
[00:13:27][I][i2c.arduino:054]: Results from i2c bus scan:
[00:13:27][I][i2c.arduino:060]: Found i2c device at address 0x27
I tried to change my ESP32, I tried to change the MCP23017, I tried to change the wires… same result.
I precise I use a little board for the MCP23017 called CJMCU-2317 which is an all-in-one solution : the RESET is already connected to VCC through a 10K resistor and the A0,A1,A2 pins are pulled down to ground with 10K resistors also.
It seems to be a power problem, not enough current or somethink like that…
If someone can help me to find the problem It will save me a lot of time! (and nights 
)
Thanks !