Problem with UART(Serial/Serial1) in GD32F10x (GD32F103C8)

[michpro]

After uploading a simple compiled programme:

#define LED     LED_BUILTIN
#define DELAY   500
#define SERIAL  Serial

void setup()
{
  pinMode(LED, OUTPUT);
  SERIAL.begin(115200);
}

void loop()
{
    digitalWrite(LED, HIGH);
    delay(DELAY);
    digitalWrite(LED, LOW);
    delay(DELAY);

    SERIAL.println("TEST");
}

there is no activity on the PA9 (Serial1 TX) pins of the processor.

After changing the port to Serial2 or Serial3, transmission appears on the PA2 or PB10 pins, respectively.

[maxgerhardt]

Screenshot of your Arduino IDE -> Tools settings or the platformio.ini?

[michpro]

[maxgerhardt]

That's weird, the Serial macro pins are correctly setup to be PA9 (TX) and PA10 (RX), per

ArduinoCore-GD32/variants/GD32F103C8_GENERIC/variant.h

Lines 151 to 157 in 9f1c9f1

	#define HAVE_HWSERIAL1
	#ifndef SERIAL0_RX
	#define SERIAL0_RX PA10
	#endif
	#ifndef SERIAL0_TX
	#define SERIAL0_TX PA9
	#endif

The pinmap definitions also seem okay

ArduinoCore-GD32/variants/GD32F103C8_GENERIC/PeripheralPins.c

Lines 189 to 204 in 9f1c9f1

	const PinMap PinMap_UART_TX[] = {
	{PORTA_2, USART1, PIN_MODE_AF_PP}, /* USART1_TX */
	{PORTA_9, USART0, GD_PIN_FUNCTION5(PIN_MODE_AF, PIN_OTYPE_PP, PIN_PUPD_PULLUP, DISABLE_USART0_REMAP)}, /* USART0_TX */
	{PORTB_6, USART0, GD_PIN_FUNCTION5(PIN_MODE_AF, PIN_OTYPE_PP, PIN_PUPD_PULLUP, USART0_REMAP)}, /* USART0_TX */
	{PORTB_10, USART2, PIN_MODE_AF_PP}, /* USART2_TX */
	{NC, NC, 0}
	};
	/* UART_RX PinMap */
	const PinMap PinMap_UART_RX[] = {
	{PORTA_3, USART1, GPIO_MODE_IN_FLOATING}, /* USART1_RX */
	{PORTA_10, USART0, GD_PIN_FUNCTION5(PIN_MODE_AF, PIN_OTYPE_PP, PIN_PUPD_PULLUP, DISABLE_USART0_REMAP)}, /* USART0_RX */
	{PORTB_7, USART0, GD_PIN_FUNCTION5(PIN_MODE_AF, PIN_OTYPE_PP, PIN_PUPD_PULLUP, USART0_REMAP)}, /* USART0_RX */
	{PORTB_11, USART2, GPIO_MODE_IN_FLOATING}, /* USART2_RX */
	{NC, NC, 0}
	};

When you add this in your sketch

#if SERIAL0_TX != PA9
#error "UNEXPECTED SERIAL TX PIN"
#endif

Does it error out?

[michpro]

With the addition of a check, there are no compilation errors.

[michpro]

I checked GPIO PA9 (I redirected ‘Blink’ there), and it is OK, so I also ruled out the suspicion of port damage.

[maxgerhardt]

There may be something wrong with the remap logic. Can you overwrite your PeripheralPins.c UART section with this and recompile?

/* UART_TX PinMap */
const PinMap PinMap_UART_TX[] = {
    {PORTA_2,       USART1, PIN_MODE_AF_PP},       /* USART1_TX */
    {PORTA_9,       USART0, PIN_MODE_AF_PP}, /* USART0_TX */
    {PORTB_6,       USART0, GD_PIN_FUNCTION5(PIN_MODE_AF, PIN_OTYPE_PP, PIN_PUPD_PULLUP, USART0_REMAP)}, /* USART0_TX */
    {PORTB_10,      USART2, PIN_MODE_AF_PP},       /* USART2_TX */
    {NC,   NC,    0}
};

/* UART_RX PinMap */
const PinMap PinMap_UART_RX[] = {
    {PORTA_3,       USART1, GPIO_MODE_IN_FLOATING}, /* USART1_RX */
    {PORTA_10,      USART0, GPIO_MODE_IN_FLOATING}, /* USART0_RX */
    {PORTB_7,       USART0, GD_PIN_FUNCTION5(PIN_MODE_AF, PIN_OTYPE_PP, PIN_PUPD_PULLUP, USART0_REMAP)}, /* USART0_RX */
    {PORTB_11,      USART2, GPIO_MODE_IN_FLOATING}, /* USART2_RX */
    {NC,   NC,    0}
};

[michpro]

With this change, it started working :)

[maxgerhardt]

I temporarily rewrote the pins that had only "DISABLE_.." as their remap macro to not try to disable the remap in c6c5e46.

Please pull again and retry. This fix also affects I2C, SPI and PWM pins.

I will need to investigate later on why disabling the remap (which should be off by default anyway) breaks the pin so badly. Theoretically, it shouldn't have had an effect.