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boards/samr21-xpro/include/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.


#define CLOCK_USE_PLL   (1)
 External oscillator and clock configuration. More...
#define CLOCK_PLL_MUL   (47U) /* must be >= 31 & <= 95 */
#define CLOCK_PLL_DIV   (1U) /* adjust to your needs */
#define CLOCK_CORECLOCK   (((CLOCK_PLL_MUL + 1) * 1000000U) / CLOCK_PLL_DIV)
Timer peripheral configuration
#define TIMER_NUMOF   (2U)
#define TIMER_0_EN   1
#define TIMER_1_EN   1
#define TIMER_0_DEV   TC3->COUNT16
#define TIMER_0_CHANNELS   2
#define TIMER_0_MAX_VALUE   (0xffff)
#define TIMER_0_ISR   isr_tc3
#define TIMER_1_DEV   TC4->COUNT32
#define TIMER_1_CHANNELS   2
#define TIMER_1_MAX_VALUE   (0xffffffff)
#define TIMER_1_ISR   isr_tc4
I2C configuration
#define I2C_NUMOF   (1U)
#define I2C_0_EN   1
#define I2C_1_EN   0
#define I2C_2_EN   0
#define I2C_3_EN   0
#define I2C_IRQ_PRIO   1
#define I2C_0_DEV   SERCOM3->I2CM
#define I2C_0_IRQ   SERCOM3_IRQn
#define I2C_0_ISR   isr_sercom3
#define I2C_0_SDA   GPIO_PIN(PA, 16)
#define I2C_0_SCL   GPIO_PIN(PA, 17)
#define I2C_0_MUX   GPIO_MUX_D
RTC configuration
#define RTC_NUMOF   (1U)
#define RTC_DEV   RTC->MODE2
RTT configuration
#define RTT_NUMOF   (1U)
#define RTT_DEV   RTC->MODE0
#define RTT_IRQ   RTC_IRQn
#define RTT_IRQ_PRIO   10
#define RTT_ISR   isr_rtc
#define RTT_MAX_VALUE   (0xffffffff)
#define RTT_FREQUENCY   (32768U) /* in Hz. For changes see `rtt.c` */
#define RTT_RUNSTDBY   (1) /* Keep RTT running in sleep states */

UART configuration

#define UART_0_ISR   isr_sercom0
#define UART_1_ISR   isr_sercom5
#define UART_NUMOF   (sizeof(uart_config) / sizeof(uart_config[0]))
static const uart_conf_t uart_config []

PWM configuration

#define PWM_0_EN   1
#define PWM_1_EN   1
#define PWM_MAX_CHANNELS   3
#define PWM_NUMOF   (2U)
static const pwm_conf_t pwm_config []

SPI configuration

#define SPI_NUMOF   (sizeof(spi_config) / sizeof(spi_config[0]))
static const spi_conf_t spi_config []

Macro Definition Documentation

#define CLOCK_USE_PLL   (1)

For selection of the used CORECLOCK, we have implemented two choices:

  • 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 we use this option as 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

Definition at line 65 of file boards/samr21-xpro/include/periph_conf.h.

Variable Documentation

const pwm_conf_t pwm_config[]
Initial value:
= {
{TCC1, {
{ GPIO_PIN(PA, 6), GPIO_MUX_E, 0 },
{ GPIO_PIN(PA, 7), GPIO_MUX_E, 1 },
{TCC0, {
{ GPIO_PIN(PA, 16), GPIO_MUX_F, 0 },
{ GPIO_PIN(PA, 18), GPIO_MUX_F, 2 },
{ GPIO_PIN(PA, 19), GPIO_MUX_F, 3 }
select peripheral function E
#define GPIO_PIN(x, y)
Define a CPU specific GPIO pin generator macro.
select peripheral function F
Available MUX values for configuring a pin's alternate function.
#define GPIO_UNDEF
Define a custom GPIO_UNDEF value.

Definition at line 144 of file boards/samr21-xpro/include/periph_conf.h.

const spi_conf_t spi_config[]
Initial value:
= {
.dev = &SERCOM4->SPI,
.miso_pin = GPIO_PIN(PC, 19),
.mosi_pin = GPIO_PIN(PB, 30),
.clk_pin = GPIO_PIN(PC, 18),
.miso_mux = GPIO_MUX_F,
.mosi_mux = GPIO_MUX_F,
.clk_mux = GPIO_MUX_F,
.miso_pad = SPI_PAD_MISO_0,
.dev = &SERCOM5->SPI,
.miso_pin = GPIO_PIN(PB, 2),
.mosi_pin = GPIO_PIN(PB, 22),
.clk_pin = GPIO_PIN(PB, 23),
.miso_mux = GPIO_MUX_D,
.mosi_mux = GPIO_MUX_D,
.clk_mux = GPIO_MUX_D,
.miso_pad = SPI_PAD_MISO_0,
select peripheral function D
#define GPIO_PIN(x, y)
Define a CPU specific GPIO pin generator macro.
select peripheral function F
use pad 2 for MOSI, pad 3 for SCK

Definition at line 171 of file boards/samr21-xpro/include/periph_conf.h.

const uart_conf_t uart_config[]
Initial value:
= {
.dev = &SERCOM0->USART,
.rx_pin = GPIO_PIN(PA,5),
.tx_pin = GPIO_PIN(PA,4),
.mux = GPIO_MUX_D,
.rx_pad = UART_PAD_RX_1,
.tx_pad = UART_PAD_TX_0
.dev = &SERCOM5->USART,
.rx_pin = GPIO_PIN(PA,23),
.tx_pin = GPIO_PIN(PA,22),
.mux = GPIO_MUX_D,
.rx_pad = UART_PAD_RX_1,
.tx_pad = UART_PAD_TX_0
select peripheral function D
#define GPIO_PIN(x, y)
Define a CPU specific GPIO pin generator macro.

Definition at line 106 of file boards/samr21-xpro/include/periph_conf.h.