periph_conf_common.h File Reference

Configurations of the MCU periphery that are common for all ESP8266 boards. More...

Detailed Description

Configurations of the MCU periphery that are common for all ESP8266 boards.

Gunar Schorcht

Definition in file periph_conf_common.h.

#include "board.h"
#include "periph_cpu.h"
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#define BIT(X)   (1<<(X))

ADC configuration

ESP8266 provides one ADC pin that is broken out on all boards.

#define ADC_NUMOF   1
 number of ADC channels

PWM configuration

The hardware implementation of ESP8266 PWM supports only frequencies as power of two.

Therefore a software implementation of one PWM device PWM_DEV(0) with up to 8 PWM channels (PWM_CHANNEL_NUM_MAX) is used.

The minumum PWM period that can be realized is 10 us or 100.000 PWM clock cycles per second. Therefore, the product of frequency and resolution should not be greater than 100.000. Otherwise the frequency is scaled down automatically.
#define PWM_NUMOF   (1)
 Number of PWM devices.
#define PWM_CHANNEL_NUM_MAX   (8)
 Maximum number of channels per PWM device.
 Definition of GPIOs that can be used as PWM channels of device PWM_DEV(0). More...
#define PWM0_DEV   PWM_DEV(0)
 Alternative device definition.

SPI configuration

ESP8266 provides two hardware SPI interfaces:

FSPI for flash memory and usually simply referred to as SPI
HSPI for peripherals

Even though FSPI (or simply SPI) is a normal SPI interface, it is not possible to use it for peripherals. HSPI is therefore the only usable SPI interface available for peripherals as RIOT's SPI_DEV(0).

The pin configuration of the HSPI interface SPI_DEV(0) is fixed. The only pin definition that can be overridden by an application-specific board configuration is the CS signal defined by SPI0_CS0_GPIO.

Signal Pin
SPI_DEV(0).CS GPIOn with n = 0, 2, 4, 5, 15, 16 (additionally 9, 10 in DOUT flash mode)
#define SPI_NUMOF   1
 Number of SPI interfaces.
#define SPI_DEV(x)   ((unsigned int)(x+1))
 SPI_DEV to SPI hardware mapping.
#define SPI0_DEV   SPI_DEV(0)
 HSPI / SPI_DEV(0) device.
#define SPI0_MISO_GPIO   GPIO12
 HSPI / SPI_DEV(0) MISO pin.
#define SPI0_MOSI_GPIO   GPIO13
 HSPI / SPI_DEV(0) MOSI pin.
#define SPI0_SCK_GPIO   GPIO14
 HSPI / SPI_DEV(0) SCK pin.
#define SPI0_CS0_GPIO   GPIO15
 HSPI / SPI_DEV(0) CS default pin, only used when cs parameter in spi_acquire is GPIO_UNDEF.

Timer configuration

#define TIMER_NUMOF   (1U)
 number of timer devices
#define TIMER_CHANNELS   (1U)
 number of channels per timer device

UART configuration

All ESP8266 boards have exactly one UART device with fixed pin mapping.

This UART device is used for flashing and as a console interface. Therefore, the number of UART devices is fixed and can not be overridden. Used pins are determined by the MCU implementation and are defined here only for documentation reasons.

#define UART_NUMOF   1
 Number of UART devices.
#define UART0_TXD   GPIO1
 TxD pin of UART_DEV(0)
#define UART0_RXD   GPIO3
 RxD pin of UART_DEV(0)

Macro Definition Documentation



Definition of GPIOs that can be used as PWM channels of device PWM_DEV(0).

The following definition is just an example configuration. Declare up to PWM_CHANNEL_NUM_MAX GPIOs as PWM channels. GPIOs with a duty cycle value of 0 can be used as normal GPIOs for other purposes. GPIOs in the list that are used for other purposes, e.g., I2C or SPI, are then not available as PWM channels.

Definition at line 76 of file periph_conf_common.h.