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Problems using the UART of the SAMD21

antouriel123

I have a problem running the UART, the microcontroller I am using is the SAMD21G18A and this is the code:

this is uart.h:

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#ifndef _uart_H_
#define _uart_H_
/* DEFINICIONES DEL UART */
#define UART5 SERCOM5->USART
extern void UART_Init(void);
extern void UART_Tx(unsigned char DATO);
extern unsigned char UART_Rx(void);
#endif /* _uart_H_ */
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this is uart.c:

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#include <samd21.h>
#include "uart.h"
void UART_Init(void)
{
GCLK->GENCTRL.reg=GCLK_CLKCTRL_ID_SERCOM5_CORE|GCLK_CLKCTRL_GEN_GCLK0; //Conecta el Generador generico 0 al SERCOM5
PM->APBCMASK.reg|=PM_APBCMASK_SERCOM5; //Habilita el bus que conecta al SERCOM 5
UART5.CTRLA.reg=
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_DORD; //LSB se transmite primero
UART5.CTRLA.reg&=~SERCOM_USART_CTRLA_CMODE; //Seleccionamos la comunicacion asincrono
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_FORM(0x0); //Sin paridad
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_TXPO(0x1)|SERCOM_USART_CTRLA_RXPO(0x3); //Configuramos el PAD[2] como Tx y el PAD[3] como Rx
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_SAMPR(0x3);//Selecionamos una tasa de muestreo de 8x con BAUD fracional
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_MODE(0x1); //Usa el reloj interno
UART5.CTRLB.reg|=SERCOM_USART_CTRLB_RXEN|SERCOM_USART_CTRLB_TXEN; //Habilita los pines Rx y Tx
UART5.CTRLB.reg&=~SERCOM_USART_CTRLB_SBMODE; //Con un bit de stop
UART5.CTRLB.reg|=SERCOM_USART_CTRLB_CHSIZE(0x0); //Selecciona el formato de 8 bits
UART5.BAUD.reg=SERCOM_USART_BAUD_FRAC_BAUD(0x68)|SERCOM_USART_BAUD_FRAC_FP(0x4);
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_ENABLE; //Habilita el UART 5
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and this is the pin configuration

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#ifndef _gpio_H_
#define _gpio_H_
/* DEFINICIONES DE PUERTOS */
#define PORTB PORT->Group[1]
extern void GPIO_Init(void);
#endif /* _gpio_H_ */
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this is gpio.c

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#include <samd21.h> //Device header
#include "gpio.h"
void GPIO_Init(void)
{
//Configuramos el PIN PB22 Tx
PORTB.DIRSET.reg=PORT_PB22;
PORTB.PINCFG[22].reg=PORT_PINCFG_PMUXEN;
PORTB.PMUX[11].reg=PORT_PMUX_PMUXE(0x3);
//Configuramos el PIN PB23 Rx
PORTB.DIRCLR.reg=PORT_PB23;
PORTB.PINCFG[23].reg=PORT_PINCFG_INEN|PORT_PINCFG_PMUXEN;
PORTB.PMUX[11].reg=PORT_PMUX_PMUXO(0x3);
}
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#include <samd21.h>
#include "uart.h"
void UART_Init(void)
{
GCLK->GENCTRL.reg=GCLK_CLKCTRL_ID_SERCOM5_CORE|GCLK_CLKCTRL_GEN_GCLK0; //Conecta el Generador generico 0 al SERCOM5
PM->APBCMASK.reg|=PM_APBCMASK_SERCOM5; //Habilita el bus que conecta al SERCOM 5
UART5.CTRLA.reg=
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_DORD; //LSB se transmite primero
UART5.CTRLA.reg&=~SERCOM_USART_CTRLA_CMODE; //Seleccionamos la comunicacion asincrono
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_FORM(0x0); //Sin paridad
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_TXPO(0x1)|SERCOM_USART_CTRLA_RXPO(0x3); //Configuramos el PAD[2] como Tx y el PAD[3] como Rx
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_SAMPR(0x3);//Selecionamos una tasa de muestreo de 8x con BAUD fracional
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_MODE(0x1); //Usa el reloj interno
UART5.CTRLB.reg|=SERCOM_USART_CTRLB_RXEN|SERCOM_USART_CTRLB_TXEN; //Habilita los pines Rx y Tx
UART5.CTRLB.reg&=~SERCOM_USART_CTRLB_SBMODE; //Con un bit de stop
UART5.CTRLB.reg|=SERCOM_USART_CTRLB_CHSIZE(0x0); //Selecciona el formato de 8 bits
UART5.BAUD.reg=SERCOM_USART_BAUD_FRAC_BAUD(0x68)|SERCOM_USART_BAUD_FRAC_FP(0x4);
UART5.CTRLA.reg|=SERCOM_USART_CTRLA_ENABLE; //Habilita el UART 5
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The exercise that I try to do is the famous ECO, that is to say that I try that what I write in the Tx sends it again by the Rx bus, I modified it and I have tried it by the debug and it stays in the line of the uart.c

while(UART5.SYNCBUSY.reg&SERCOM_USART_SYNCBUSY_ENABLE); //Espera a que se habilite el UART

i don't know if the uart configuration is wrong or missing, i got this code from a book:

"Atmel ARM Programming for Embedded Systems"

authors:

Muhammad Ali Mazidi,
Shujen Chen,
Eshragh Ghaemi.

i want to know if this book is wrong and so recommended is that book or I have it wrong, thank you very much and i hope your answer soon. Before I forget, the operating frequency of the microcontroller is 8 MHz

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