periph_conf.h File Reference

Configuration of CPU peripherals for the Atmel SAM D21 Xplained Pro board. More...

Detailed Description

Configuration of CPU peripherals for the Atmel SAM D21 Xplained Pro board.

Author
Travis Griggs travi.nosp@m.sgri.nosp@m.ggs@g.nosp@m.mail.nosp@m..com
Dan Evans photo.nosp@m.nthu.nosp@m.nder@.nosp@m.gmai.nosp@m.l.com

Definition in file periph_conf.h.

#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:

CORECLOCK = ((PLL_MUL + 1) * 1MHz) / PLL_DIV

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:

CORECLOCK = 8MHz / DIV

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_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_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_sercom3
 
#define UART_1_ISR   isr_sercom4
 
#define UART_2_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   0
 
#define PWM_2_EN   0
 
#define PWM_NUMOF   ARRAY_SIZE(pwm_config)
 
static const pwm_conf_chan_t pwm_chan0_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` */
 

ADC Configuration

#define ADC_PRESCALER   ADC_CTRLB_PRESCALER_DIV512
 
#define ADC_NEG_INPUT   ADC_INPUTCTRL_MUXNEG_GND
 
#define ADC_GAIN_FACTOR_DEFAULT   ADC_INPUTCTRL_GAIN_1X
 
#define ADC_REF_DEFAULT   ADC_REFCTRL_REFSEL_INT1V
 
#define ADC_NUMOF   ARRAY_SIZE(adc_channels)
 
static const adc_conf_chan_t adc_channels []
 

DAC configuration

#define DAC_CLOCK   SAM0_GCLK_1MHZ
 
#define DAC_VREF   DAC_CTRLB_REFSEL_AVCC
 

Variable Documentation

◆ adc_channels

const adc_conf_chan_t adc_channels[]
static
Initial value:
= {
{GPIO_PIN(PB, 0), ADC_INPUTCTRL_MUXPOS_PIN8},
{GPIO_PIN(PB, 1), ADC_INPUTCTRL_MUXPOS_PIN9},
{GPIO_PIN(PA, 10), ADC_INPUTCTRL_MUXPOS_PIN18},
{GPIO_PIN(PA, 11), ADC_INPUTCTRL_MUXPOS_PIN19},
{GPIO_PIN(PA, 2), ADC_INPUTCTRL_MUXPOS_PIN0},
{GPIO_PIN(PA, 3), ADC_INPUTCTRL_MUXPOS_PIN1}
}

Definition at line 340 of file periph_conf.h.

◆ i2c_config

const i2c_conf_t i2c_config[]
static
Initial value:
= {
{
.dev = &(SERCOM2->I2CM),
.speed = I2C_SPEED_NORMAL,
.scl_pin = GPIO_PIN(PA, 9),
.sda_pin = GPIO_PIN(PA, 8),
.mux = GPIO_MUX_D,
.gclk_src = SAM0_GCLK_MAIN,
.flags = I2C_FLAG_NONE
}
}

Definition at line 305 of file periph_conf.h.

◆ pwm_chan0_config

const pwm_conf_chan_t pwm_chan0_config[]
static
Initial value:
= {
{ GPIO_PIN(PA, 12), GPIO_MUX_E, 0 },
{ GPIO_PIN(PA, 13), GPIO_MUX_E, 1 },
}

Definition at line 203 of file periph_conf.h.

◆ pwm_config

const pwm_conf_t pwm_config[]
static
Initial value:
= {
{TCC_CONFIG(TCC2), pwm_chan0_config, ARRAY_SIZE(pwm_chan0_config), SAM0_GCLK_MAIN},
}

Definition at line 227 of file periph_conf.h.

◆ timer_config

const tc32_conf_t timer_config[]
static
Initial value:
= {
{
.dev = TC3,
.irq = TC3_IRQn,
.pm_mask = PM_APBCMASK_TC3,
.gclk_ctrl = GCLK_CLKCTRL_ID_TCC2_TC3,
.gclk_src = SAM0_GCLK_1MHZ,
.flags = TC_CTRLA_MODE_COUNT16,
},
{
.dev = TC4,
.irq = TC4_IRQn,
.pm_mask = PM_APBCMASK_TC4 | PM_APBCMASK_TC5,
.gclk_ctrl = GCLK_CLKCTRL_ID_TC4_TC5,
.gclk_src = SAM0_GCLK_1MHZ,
.flags = TC_CTRLA_MODE_COUNT32,
}
}

Definition at line 100 of file periph_conf.h.

SAM0_GCLK_MAIN
@ SAM0_GCLK_MAIN
48 MHz main clock
Definition: periph_cpu.h:59
GPIO_MUX_E
@ GPIO_MUX_E
select peripheral function E
Definition: periph_cpu_common.h:140
I2C_SPEED_NORMAL
@ I2C_SPEED_NORMAL
normal mode: ~100 kbit/s
Definition: i2c.h:177
I2C_FLAG_NONE
@ I2C_FLAG_NONE
No flags set.
Definition: periph_cpu_common.h:407
PB
@ PB
port B
Definition: periph_cpu_common.h:89
ARRAY_SIZE
#define ARRAY_SIZE(a)
Calculate the number of elements in a static array.
Definition: kernel_defines.h:122
GPIO_PIN
#define GPIO_PIN(x, y)
Define a CPU specific GPIO pin generator macro.
Definition: periph_cpu.h:35
GPIO_MUX_D
@ GPIO_MUX_D
select peripheral function D
Definition: periph_cpu_common.h:139
PA
@ PA
port A
Definition: periph_cpu_common.h:88
SAM0_GCLK_1MHZ
@ SAM0_GCLK_1MHZ
1 MHz clock for xTimer
Definition: periph_cpu.h:60
TCC_CONFIG
#define TCC_CONFIG(tim)
Static initializer for TCC timer configuration.
Definition: periph_cpu_common.h:297