ESP32 Forum

Datasheet describes that U(S)ART is able to work on any GPIO, but there are some pins labeled as UnRXD and UnTXD (n is a number).
What are they for? Programming on U0RXD and U0TXD only?

Hi Mick,

Programming is via the marked UART0 pins only, this is because the UART bootloader runs from ROM so there's no way to reconfigure these pins. However, once your program is running you can use the GPIO Matrix functionality to reroute the UARTs to any pins.

The other pin labels are for using "IOMUX" to choose pin functions, which is less flexible so less useful now that it's possible to use the GPIO Matrix instead (it is necessary to use IOMUX for very high speed / low latency signals, but there is no downside to using GPIO Matrix for UART signals.)

The technical reference manual Chapter 4 explains the GPIO Matrix & IOMUX in detail: http://espressif.com/en/support/download/documents

Angus

ESP_Angus wrote: The technical reference manual Chapter 4 explains the GPIO Matrix & IOMUX in detail: http://espressif.com/en/support/download/documents

Angus

hi Angus,

do you know, will the reference updated with this ?
txs

best wishes
rudi

rudi ;-) wrote:

ESP_Angus wrote: do you know, will the reference updated with this ?

I think probably not until we release more details about the CAN controller.