Accessing MilkVDuo-Arduino serial ports

Duo
1

Hello
(I have just edited this to make my question clearer)

I want to use 3 UARTS in Arduino running on the Duo.

This example in the Duo Arduino documentation shows access to UART 3:

void setup() {
  Serial3.begin(115200);
}

void loop() {
  Serial3.printf("hello world\r\n");
  delay(1000);
}

I am just wondering if there is there a way to access the other serial ports (UARTS 1,2,4) in an Arduino program?

For example, the overall pinout for Duo shows UART 4 on GPIO 2/3 (pins 4/5)
But if I try to use Serial4 as below, this doesn’t work:

void setup() {
  Serial4.begin(115200);
}

void loop() {
  Serial4.printf("hello world\r\n");
  delay(1000);
}

Does anyone have any suggestions?
Thankyou

2

try using a lower baud rate.

3

hi Thanks for the suggestion.
Yes I have tried very low baud rates down to 4800.
The Serial3 port works but none of the others.
Nothing happens with the other port numbers.

4

Sorry, I was using my own modified firmware so my suggestion was incorrect.

You will need to rebuild the firmware in order to enable the other serial ports. Only UART0 and Uart4 are enabled on the stock firmware.

Change this line and add the following:

&uart1 {
	status = "okay";
};
&uart2 {
	status = "okay";
};
&uart3 {
	status = "okay";
};

Make sure to use the arduino branch when building the sdk.

5

Thanks for the reply and the instruction.
I will try that. But first I’ll have to learn how to “rebuild the firmware”
Best Rgds