June 25, 2024, 05:50:23 PM

I2C with ESP32-POE

Started by espethuser, November 28, 2020, 10:26:14 PM

Previous topic - Next topic

espethuser

I'm using the ESP32-POE with ethernet, both for power and communication. I'm struggling a bit for free I/O pins, so taking the Olimex advice:

Quote from: LubOlimex on June 24, 2019, 11:24:16 AMIf you need more GPIO pins consider either using additional GPIO expander board over I2C/SPI/UART

I bought an MCP23008. But I'm a bit confused which pins I should use it with. This chap seems to have used the ESP32-POE-ISO with both ethernet and I2C, but when I look at the I2C pins, 16 seems to be used by both EMAC_CLK_OUT_180 and EMAC_RX_ER so I don't really understand how that's working successfully for him.

Guidance would be really appreciated, thank you!

LubOlimex

Technical support and documentation manager at Olimex

espethuser

Quote from: LubOlimex on November 30, 2020, 09:48:01 AMPins 13 and 16 are alright.

Thank you I'm confused how pin 16 is usable when it is used by both emac_clk_out_180 AND emac_rx_er? Just don't understand enough! :-)

LubOlimex

I think you are confusing ESP32 pin #16 and GPIO #16 which is ESP32 pin #27.

The Arduino code doesn't care about ESP32 pin #; only about GPIO#.
Technical support and documentation manager at Olimex

espethuser

Are you sure I'm confusing my pins??

Here the ESP32-POE clearly shows that GPIO pin 16 is used by both emac_clk_out_180 AND emac_rx_er?

Quote from: LubOlimex on November 30, 2020, 09:48:01 AMPin 13 [is] alright.

GPIO Pin 13 is pulled up to 3v??

This board sure is hard to work with! :-)

LubOlimex

Better download and use the schematic export to track these. Here:

https://github.com/OLIMEX/ESP32-POE/blob/master/HARDWARE/ESP32-PoE-hardware-revision-K/ESP32-PoE_Rev_K.pdf

Yes, both GPI)16 and GPIO13 are pulled up. This is for I2C compatibility sake. You can pull them down or remove the resistor that connects them to 3.3V.
Technical support and documentation manager at Olimex