Esp32 uart0/1 i2c0/1

Official Hardware Nano Family Nano ESP32
1

Hi,

as far as I understood, ESP32-S3 SoC which is intergated in the NORA-W106 module, has two UART interfaces, additionaly to USB interface. On the Nano ESP32 board it looks like that there is only one “available” UART inteface - UART0 is on the pins GPIO44 (RX) and GPIO43 (RX). What about second UART - can it be used also? It looks like that it is available on pins GPIO17 and GPIO18. Is an additional UART supported within the Arduino environment?

What about I2C communication. Looks like that A4 and A5 pins are intended for the one I2C bus. What about another I2C bus - is it supported within the Arduino environment?

What about pin intended to supply the RTC block inside the ESP32-S3 SoC? I’m talking about pin VDD3V3_RTC which is available on pin 20 on this SoC. Is this pin in the Nora-W106 somehow '“routed” in a way that the RTC section is powered? Is a mandatory to use external 32 kHz while using RTC or this is just something optional to achieve better accuracy?

Thanks.

2

you can use UART1 and UART2 on any available pins (that are not bootstrap or otherwise used for other peripherals like external psram)

for example:

// initialize UART1 on 5 = RX, 6 = TX
Serial1.begin(115200, SERIAL_8N1, 5, 6);
3

you can also use the second I2C on any available pins

4

Hi,

thanks for your reply. Completly understood. However, I just realized that ESP32-S3 has 3 UART interfaces, where two have their “default” pins and the third doesn’t but it can be assigned to pins we would like to (the same as UART0 and UART1 which have their “default” pins). Is the third UART also supported within the Arduino enviroonment?

Thx.

5

yes, UART2 is supported

6

Thanks for your replies.

Now, I understood things much better. I also found “Arduino Nano ESP32 User manual” where things are explained very nicely also​:blush: Maybe it will be helpful for someone other too: https://docs.arduino.cc/tutorials/nano-esp32/cheat-sheet/#uart

I’m just not sure about Serial0. It looks like that this interface is connected with bootloader/kernel and it can print out messages occcasionally. For two way UART communication with external device it is probably better to avioid this interface, however if I connect to Serial0 a device which only streams UART data in a way in to the ESP32 (one way communication), this should not be a problem?

Which pins are used for psram and are not bootstrap - I would avoid them for using with Serial1 and Serial2?

It looks like that Arduino Nano ESP32 doesn’t have separate pin for RTC Vcc - looks like that is internally connected with general Vcc. However, while using RTC - is an external 32 kHz crystal a must or is internal RC oscillator pretty accurate? I’m planning to synhronize occasionally via NTP.

Thnx.

7

@time_document_3108 According to the schematic of the Nano ESP32 board, it looks like that pins including GPIO27 to GPIO32 are used for external flash. However these pins are not exposed externally so it looks fine. Boot pinstraps are GPIO0 and GPIO46 which are “marked” as B0 and B1.

Other pins looks safe to use for UART1 and UART2. I hope that I didn’t miss something?:blush: