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periph_conf.h File Reference

Configuration of CPU peripherals for the Atmel SAM R21 Xplained Pro board. More...

Detailed Description

#include <stdint.h>
#include "cpu.h"
#include "periph_cpu.h"
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Go to the source code of this file.

External oscillator and clock configuration

There are three choices for selection of CORECLOCK:

  • usage of the 48 MHz DFLL fed by external oscillator running at 32 kHz
  • usage of the PLL fed by the internal 8MHz oscillator divided by 8
  • usage of the internal 8MHz oscillator directly, divided by N if needed

The PLL option allows for the usage of a wider frequency range and a more stable clock with less jitter. This is why this option is default.

The target frequency is computed from the PLL multiplier and the PLL divisor. Use the following formula to compute your values:


NOTE: The PLL circuit does not run with less than 32MHz while the maximum PLL frequency is 96MHz. So PLL_MULL must be between 31 and 95!

The internal Oscillator used directly can lead to a slightly better power efficiency to the cost of a less stable clock. Use this option when you know what you are doing! The actual core frequency is adjusted as follows:


NOTE: A core clock frequency below 1MHz is not recommended

#define CLOCK_USE_PLL   (1)
#define CLOCK_USE_XOSC32_DFLL   (0)
#define GEN2_ULP32K   (0)
#define CLOCK_DIV   (1U)
#define CLOCK_CORECLOCK   (8000000 / CLOCK_DIV)

Timer peripheral configuration

#define TIMER_0_MAX_VALUE   0xffff
#define TIMER_0_ISR   isr_tc3
#define TIMER_1_ISR   isr_tc4
#define TIMER_NUMOF   ARRAY_SIZE(timer_config)
static const tc32_conf_t timer_config []

UART configuration

#define UART_0_ISR   isr_sercom0
#define UART_1_ISR   isr_sercom5
#define UART_NUMOF   ARRAY_SIZE(uart_config)
static const uart_conf_t uart_config []

PWM configuration

#define PWM_0_EN   1
#define PWM_1_EN   1
#define PWM_NUMOF   ARRAY_SIZE(pwm_config)
static const pwm_conf_t pwm_config []

SPI configuration

#define SPI_NUMOF   ARRAY_SIZE(spi_config)
static const spi_conf_t spi_config []

I2C configuration

#define I2C_NUMOF   ARRAY_SIZE(i2c_config)
static const i2c_conf_t i2c_config []

RTT configuration

#define RTT_FREQUENCY   (32768U) /* in Hz. For changes see `rtt.c` */
#define RTT_MIN_OFFSET   (10U)

ADC Configuration

#define ADC_NUMOF   ARRAY_SIZE(adc_channels)
static const adc_conf_chan_t adc_channels []

USB peripheral configuration

static const sam0_common_usb_config_t sam_usbdev_config []

Macro Definition Documentation



Definition at line 314 of file periph_conf.h.



Definition at line 313 of file periph_conf.h.


#define ADC_NUMOF   ARRAY_SIZE(adc_channels)

Definition at line 323 of file periph_conf.h.



Definition at line 311 of file periph_conf.h.



Definition at line 315 of file periph_conf.h.


#define CLOCK_CORECLOCK   (8000000 / CLOCK_DIV)

Definition at line 92 of file periph_conf.h.


#define CLOCK_DIV   (1U)

Definition at line 90 of file periph_conf.h.


#define CLOCK_USE_PLL   (1)

Definition at line 66 of file periph_conf.h.


#define CLOCK_USE_XOSC32_DFLL   (0)

Definition at line 67 of file periph_conf.h.


#define GEN2_ULP32K   (0)

Definition at line 75 of file periph_conf.h.


#define I2C_NUMOF   ARRAY_SIZE(i2c_config)

Definition at line 292 of file periph_conf.h.

◆ PWM_0_EN

#define PWM_0_EN   1

Definition at line 190 of file periph_conf.h.

◆ PWM_1_EN

#define PWM_1_EN   1

Definition at line 191 of file periph_conf.h.


#define PWM_NUMOF   ARRAY_SIZE(pwm_config)

Definition at line 232 of file periph_conf.h.


#define RTT_FREQUENCY   (32768U) /* in Hz. For changes see `rtt.c` */

Definition at line 300 of file periph_conf.h.


#define RTT_MIN_OFFSET   (10U)

Definition at line 302 of file periph_conf.h.


#define SPI_NUMOF   ARRAY_SIZE(spi_config)

Definition at line 274 of file periph_conf.h.


#define TIMER_0_ISR   isr_tc3

Definition at line 130 of file periph_conf.h.


#define TIMER_0_MAX_VALUE   0xffff

Definition at line 127 of file periph_conf.h.


#define TIMER_1_ISR   isr_tc4

Definition at line 131 of file periph_conf.h.


#define TIMER_NUMOF   ARRAY_SIZE(timer_config)

Definition at line 133 of file periph_conf.h.


#define UART_0_ISR   isr_sercom0

Definition at line 180 of file periph_conf.h.


#define UART_1_ISR   isr_sercom5

Definition at line 181 of file periph_conf.h.


#define UART_NUMOF   ARRAY_SIZE(uart_config)

Definition at line 183 of file periph_conf.h.

Variable Documentation

◆ adc_channels

const adc_conf_chan_t adc_channels[]
Initial value:
= {
{ .inputctrl = ADC_INPUTCTRL_MUXPOS_PA06 },
{ .inputctrl = ADC_INPUTCTRL_MUXPOS_PA07 },
Alias for PIN7.
Definition periph_cpu.h:126
Alias for PIN6.
Definition periph_cpu.h:125

Definition at line 317 of file periph_conf.h.

◆ i2c_config

const i2c_conf_t i2c_config[]
Initial value:
= {
.dev = &(SERCOM3->I2CM),
.speed = I2C_SPEED_NORMAL,
.scl_pin = GPIO_PIN(PA, 17),
.sda_pin = GPIO_PIN(PA, 16),
.mux = GPIO_MUX_D,
.gclk_src = SAM0_GCLK_MAIN,
.flags = I2C_FLAG_NONE
#define GPIO_PIN(x, y)
Define a CPU specific GPIO pin generator macro.
Definition periph_cpu.h:46
normal mode: ~100 kbit/s
Definition periph_cpu.h:278
@ PA
port A
No flags set.
select peripheral function D
#define SAM0_GCLK_MAIN
120 MHz main clock
Definition periph_cpu.h:74

Definition at line 281 of file periph_conf.h.

◆ pwm_config

const pwm_conf_t pwm_config[]
Initial value:
= {

Definition at line 212 of file periph_conf.h.

◆ sam_usbdev_config

const sam0_common_usb_config_t sam_usbdev_config[]
Initial value:
= {
.dm = GPIO_PIN(PA, 24),
.dp = GPIO_PIN(PA, 25),
.d_mux = GPIO_MUX_G,
.device = &USB->DEVICE,
.gclk_src = SAM0_GCLK_MAIN,
select peripheral function G

Definition at line 330 of file periph_conf.h.

◆ spi_config

const spi_conf_t spi_config[]

Definition at line 239 of file periph_conf.h.

◆ timer_config

const tc32_conf_t timer_config[]
Initial value:
= {
.dev = TC3,
.irq = TC3_IRQn,
.pm_mask = PM_APBCMASK_TC3,
.gclk_ctrl = GCLK_CLKCTRL_ID_TCC2_TC3,
.gclk_src = SAM0_GCLK_MAIN,
.dev = TC4,
.irq = TC4_IRQn,
.gclk_ctrl = GCLK_CLKCTRL_ID_TC4_TC5,
.gclk_src = SAM0_GCLK_MAIN,

Definition at line 100 of file periph_conf.h.

◆ uart_config

const uart_conf_t uart_config[]

Definition at line 140 of file periph_conf.h.