AS5047P Driver

A platform independent library for ams AS5047P rotary position sensor/magnetic encoder.

• src/: Main code.
  • as5047p.c
  • as5047p.h
• examples/: Some examples.
• LICENSE
• README.md (this file)

Usage

Install

There are 3 ways to install:

1. Go to VS Code > PIO Home > Libraries and search "as5047-driver", press the "Add to Project" button.

2. Add lib_deps = ziteh/as5047-driver@^2.0.0 in platformio.ini file, for example:

[env:nucleo_f446re]
platform = ststm32
board = nucleo_f446re
framework = stm32cube
lib_deps = ziteh/as5047-driver@^2.0.0

3. PIO CLI: pio pkg install --library "ziteh/as5047-driver@^2.0.0".

Writing the Code

Include

#include <as5047p.h>

The following functions that must be implemented in the user file (e.g. main.c), function names are free:

void as5047p_spi_send(uint16_t data);
uint16_t as5047p_spi_read(void);
void as5047p_spi_select(void);
void as5047p_spi_deselect(void);
void as5047p_delay(void)

Take STM32 HAL for example:

void as5047p_spi_send(uint16_t data)
{
  HAL_SPI_Transmit(&hspi1, (uint8_t *)&data, 1, HAL_MAX_DELAY);
}

uint16_t as5047p_spi_read(void)
{
  uint16_t data = 0;
  HAL_SPI_Receive(&hspi1, (uint8_t *)&data, 1, HAL_MAX_DELAY);
  return data;
}

void as5047p_spi_select(void)
{
  HAL_GPIO_WritePin(AS5047P_SS_GPIO_Port, AS5047P_SS_Pin, GPIO_PIN_RESET);
}

void as5047p_spi_deselect(void)
{
  HAL_GPIO_WritePin(AS5047P_SS_GPIO_Port, AS5047P_SS_Pin, GPIO_PIN_SET);
}

// For 't_CSn': High time of CSn between two transmissions, >350 ns.
void as5047p_delay(void)
{
  HAL_Delay(1);
}

Make handle and init:

as5047p_handle_t as5047p;
as5047p_make_handle(&as5047p_spi_send,
                    &as5047p_spi_read,
                    &as5047p_spi_select,
                    &as5047p_spi_deselect,
                    &as5047p_delay,
                    &as5047p);

// Configure SETTINGS1 and SETTINGS2.
as5047p_config(&as5047p, 0b00100101, 0b00000000); 

// Set specify position as zero.
as5047p_set_zero(&as5047p, 0);

Read angle in degree:

float angle_deg;
int8_t error = as5047p_get_angle(&as5047p, without_daec, &angle_deg);

if (error == 0)
{
    printf("Angle: %f\r\n", angle_deg);
}

Read raw position:

uint16_t position;
int8_t error = as5047p_get_position(&as5047p, without_daec, &position);

if (error == 0)
{
    printf("Raw: %5i\r\n", position);
}

Examples

• STM32 HAL: examples/stm32_hal/src/main.c
• STM32 LibOpenCM3: examples/stm32_libopencm3/src/main.c

My blog (Chinese) has more detailed descriptions.

AS5047P SPI Interface

• SPI Mode = 1.
  • CPOL = 0: Clock is low when idle.
  • CPHA = 1: Data is sampled on the second edge (i.e. falling edge).
• CS (chip select) pin active low.
• Data size (data frame format) is 16-bit.
• Bit order is MSB first.
• Max clock rates up to 10 MHz.
• Only supports slave operation mode.