SAMD21G18A UART

[WILDERNESSBAGEL]

I used the code ataradov's github https://github.com/ataradov/mcu-starter-projects/blob/master/samd21/main.c and the code works. However I tried to change it so it works with SERCOM5 on pins PB22 and PB23 (PAD 2 and 3, and it's SERCOM alt). I changed all SERCOMs in the code to SERCOM5 and I changed the pads to 2 for TX and 3 for RX, also I changed PORT_PMUX_PMUXE_D_Val to D instead of C, here is the complete code with the changes:

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/*
 * Copyright (c) 2015, Alex Taradov <alex@taradov.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

//-----------------------------------------------------------------------------
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include "samd21.h"
#include "hal_gpio.h"

//-----------------------------------------------------------------------------
#define PERIOD_FAST     100
#define PERIOD_SLOW     500

HAL_GPIO_PIN(UART_TX,  B, 22)
HAL_GPIO_PIN(UART_RX,  B, 23)

#define DelayTicks(ticks)              {volatile uint32_t n=ticks; while(n--);}    //takes 8 cycles
#define DelayMs(ms)                    DelayTicks(MS_TO_DLYTICKS(ms))
#define F_CPU 8000000
#define CYCLES_IN_DLYTICKS_FUNC        8
#define MS_TO_DLYTICKS(ms)    (uint32_t)(F_CPU / 1000 * ms / CYCLES_IN_DLYTICKS_FUNC) // ((float)(F_CPU)) / 1000.0

//-----------------------------------------------------------------------------
static void timer_set_period(uint16_t i)
{
  TC3->COUNT16.CC[0].reg = (F_CPU / 1000ul / 256) * i;
  TC3->COUNT16.COUNT.reg = 0;
}

//-----------------------------------------------------------------------------
void irq_handler_tc3(void)
{
  if (TC3->COUNT16.INTFLAG.reg & TC_INTFLAG_MC(1))
  {
    TC3->COUNT16.INTFLAG.reg = TC_INTFLAG_MC(1);
  }
}

//-----------------------------------------------------------------------------
static void timer_init(void)
{
  PM->APBCMASK.reg |= PM_APBCMASK_TC3;

  GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID(TC3_GCLK_ID) |
      GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN(0);

  TC3->COUNT16.CTRLA.reg = TC_CTRLA_MODE_COUNT16 | TC_CTRLA_WAVEGEN_MFRQ |
      TC_CTRLA_PRESCALER_DIV256 | TC_CTRLA_PRESCSYNC_RESYNC;

  TC3->COUNT16.COUNT.reg = 0;

  timer_set_period(PERIOD_SLOW);

  TC3->COUNT16.CTRLA.reg |= TC_CTRLA_ENABLE;

  TC3->COUNT16.INTENSET.reg = TC_INTENSET_MC(1);
  NVIC_EnableIRQ(TC3_IRQn);
}

//-----------------------------------------------------------------------------
static void uart_init(uint32_t baud)
{
  uint64_t br = (uint64_t)65536 * (F_CPU - 16 * baud) / F_CPU;

  HAL_GPIO_UART_TX_out();
  HAL_GPIO_UART_TX_pmuxen(PORT_PMUX_PMUXE_D_Val);
  HAL_GPIO_UART_RX_in();
  HAL_GPIO_UART_RX_pmuxen(PORT_PMUX_PMUXE_D_Val);

  PM->APBCMASK.reg |= PM_APBCMASK_SERCOM5;

  GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID(SERCOM5_GCLK_ID_CORE) |
      GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN(0);

  SERCOM5->USART.CTRLA.reg =
      SERCOM_USART_CTRLA_DORD | SERCOM_USART_CTRLA_MODE_USART_INT_CLK |
      SERCOM_USART_CTRLA_RXPO(3/*PAD3*/) | SERCOM_USART_CTRLA_TXPO(2/*PAD2*/);

  SERCOM5->USART.CTRLB.reg = SERCOM_USART_CTRLB_RXEN | SERCOM_USART_CTRLB_TXEN |
      SERCOM_USART_CTRLB_CHSIZE(0/*8 bits*/);

  SERCOM5->USART.BAUD.reg = (uint16_t)br;

  SERCOM5->USART.CTRLA.reg |= SERCOM_USART_CTRLA_ENABLE;
}

//-----------------------------------------------------------------------------
static void uart_putc(char c)
{
  while (!(SERCOM5->USART.INTFLAG.reg & SERCOM_USART_INTFLAG_DRE));
  SERCOM5->USART.DATA.reg = c;
}

//-----------------------------------------------------------------------------
static void uart_puts(char *s)
{
  while (*s)
    uart_putc(*s++);
}

//-----------------------------------------------------------------------------
static void sys_init(void)
{
  // Switch to 8MHz clock (disable prescaler)
  SYSCTRL->OSC8M.bit.PRESC = 0;
}

//-----------------------------------------------------------------------------
int main(void)
{
  uint32_t cnt = 0;
  bool fast = false;

  sys_init();
  timer_init();
  uart_init(115200);

  uart_puts("\r\nHello, world!\r\n");



  while (1)
  {

    if (5000 == cnt)
    {
      fast = !fast;
      timer_set_period(fast ? PERIOD_FAST : PERIOD_SLOW);
      uart_putc('.');
    }
else{
uart_puts("\r\nHello, world!\r\n");
DelayMs(1000);
}

  }

  return 0;
}


Did I miss something?

[WILDERNESSBAGEL]

OK I figured it out SERCOM_USART_CTRLA_RXPO and SERCOM_USART_CTRLA_TXPO don't represent pads directly the correct settings are,  SERCOM_USART_CTRLA_RXPO(3/*PAD1*/) | SERCOM_USART_CTRLA_TXPO(1/*PAD0*/); more info on page 432 in the datasheet https://ww1.microchip.com/downloads/en/DeviceDoc/SAM_D21_DA1_Family_DataSheet_DS40001882F.pdf#page=432