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/*
* Copyright (c) 2021, Joey Castillo
* SAML22 starter project is Copyright (c) 2014-2017, 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 "saml22.h"
#include "hal_gpio.h"
//-----------------------------------------------------------------------------
HAL_GPIO_PIN(LED, A, 21)
HAL_GPIO_PIN(UART_TX, B, 0)
HAL_GPIO_PIN(UART_RX, B, 2)
//-----------------------------------------------------------------------------
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(HAL_GPIO_PMUX_C);
HAL_GPIO_UART_RX_in();
HAL_GPIO_UART_RX_pmuxen(HAL_GPIO_PMUX_C);
MCLK->APBCMASK.reg |= MCLK_APBCMASK_SERCOM3;
GCLK->PCHCTRL[SERCOM3_GCLK_ID_CORE].reg = GCLK_PCHCTRL_GEN(0) | GCLK_PCHCTRL_CHEN;
while (0 == (GCLK->PCHCTRL[SERCOM3_GCLK_ID_CORE].reg & GCLK_PCHCTRL_CHEN));
SERCOM3->USART.CTRLA.reg =
SERCOM_USART_CTRLA_DORD | SERCOM_USART_CTRLA_MODE(1/*USART_INT_CLK*/) |
SERCOM_USART_CTRLA_RXPO(0/*PAD0*/) | SERCOM_USART_CTRLA_TXPO(1/*PAD2*/);
SERCOM3->USART.CTRLB.reg = SERCOM_USART_CTRLB_RXEN | SERCOM_USART_CTRLB_TXEN |
SERCOM_USART_CTRLB_CHSIZE(0/*8 bits*/);
SERCOM3->USART.BAUD.reg = (uint16_t)br;
SERCOM3->USART.CTRLA.reg |= SERCOM_USART_CTRLA_ENABLE;
}
//-----------------------------------------------------------------------------
static void uart_putc(char c) {
while (!(SERCOM3->USART.INTFLAG.reg & SERCOM_USART_INTFLAG_DRE));
SERCOM3->USART.DATA.reg = c;
}
//-----------------------------------------------------------------------------
static void uart_puts(char *s) {
while (*s) uart_putc(*s++);
}
//-----------------------------------------------------------------------------
static void sys_init(void) {
// Switch to 16MHz clock (disable prescaler)
OSCCTRL->OSC16MCTRL.reg = OSCCTRL_OSC16MCTRL_ENABLE | OSCCTRL_OSC16MCTRL_FSEL_16;
// Switch to the highest performance level
PM->INTFLAG.reg = PM_INTFLAG_PLRDY;
PM->PLCFG.reg = PM_PLCFG_PLSEL_PL2_Val;
while (!PM->INTFLAG.reg);
}
//-----------------------------------------------------------------------------
int main(void) {
sys_init();
uart_init(115200);
HAL_GPIO_LED_out();
HAL_GPIO_LED_set();
uart_puts("\r\nHello, world!\r\n");
while (1) {
uart_putc('.');
}
return 0;
}
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