AS5048A SPI - Magnetic rotary encoder library

Library for communication over the SPI interface with the ams.com AS5048A magnetic rotary encoder.

Example:

Simple readout of a single angle measurement from a single sensor on the SPI-bus

#include "mbed.h"
#include <as5048spi.h>

// The sensors connection are attached to pins 5-8
As5048Spi sensor(p5, p6, p7, p8);
Serial pc(USBTX, USBRX); // tx, rx

int main() {
    while(1) {
        // 
        const int* angles = sensor.read_angle();
        int angle = angles[0];
        
        // The read angle returns the value returned over the SPI bus, including parity bit
        pc.printf("Read result: %x\r\n", angle);
        
        if( As5048Spi::parity_check(angle) )
        {
            // Convert range from 0 to 2^14-1 to 0 - 360 degrees
            int degrees = As5048Spi::degrees(angle)/100;
            pc.printf("Parity check succesfull.\r\n");
            pc.printf("Angle: %i degrees\r\n", degrees );
        }
        else
        {
            pc.printf("Parity check failed.\r\n");
        }
            
        wait_ms(500);
    }
}

The class supports daisy chaining multiple sensors on the SPI-bus as well. See: SPI-Daisy-Chaining.

Committer:
JSpikker
Date:
Thu Dec 04 10:00:42 2014 +0000
Revision:
2:2958500883e0
Parent:
0:3edcf58e51e7
Child:
3:a8ad32e439d4
Added burst read functionality

Who changed what in which revision?

UserRevisionLine numberNew contents of line
JSpikker 0:3edcf58e51e7 1 #include "mbed.h"
JSpikker 0:3edcf58e51e7 2 typedef enum {
JSpikker 0:3edcf58e51e7 3 AS_FLAG_PARITY = 0x8000,
JSpikker 0:3edcf58e51e7 4 AS_FLAG_READ = 0x4000,
JSpikker 0:3edcf58e51e7 5 } As5048Flag;
JSpikker 0:3edcf58e51e7 6
JSpikker 0:3edcf58e51e7 7 typedef enum {
JSpikker 0:3edcf58e51e7 8 AS_CMD_NOP = 0x0000,
JSpikker 0:3edcf58e51e7 9 AS_CMD_ERROR = 0x0001 | AS_FLAG_READ, // Reads error ireguster and clear error flags
JSpikker 0:3edcf58e51e7 10 AS_CMD_DIAGNOSTICS = 0x3FFD | AS_FLAG_READ, // Reads automatic gain control and diagnostics info
JSpikker 0:3edcf58e51e7 11 AS_CMD_MAGNITUDE = 0x3FFE | AS_FLAG_READ,
JSpikker 0:3edcf58e51e7 12
JSpikker 0:3edcf58e51e7 13 AS_CMD_ANGLE = 0x3FFF| AS_FLAG_PARITY | AS_FLAG_READ,
JSpikker 0:3edcf58e51e7 14 } As5048Command;
JSpikker 0:3edcf58e51e7 15
JSpikker 2:2958500883e0 16 // Masks for bits in the result of the AS_CMD_DIAGNOSTICS command
JSpikker 2:2958500883e0 17 typedef enum {
JSpikker 2:2958500883e0 18 AS_DIAG_CORDIC_OVERFLOW = 0x0200,
JSpikker 2:2958500883e0 19 AS_DIAG_HIGH_MAGNETIC = 0x0400,
JSpikker 2:2958500883e0 20 AS_DIAG_LOW_MAGNETIC = 0x0800,
JSpikker 2:2958500883e0 21 } As5048Diagnostics;
JSpikker 2:2958500883e0 22
JSpikker 0:3edcf58e51e7 23
JSpikker 0:3edcf58e51e7 24
JSpikker 0:3edcf58e51e7 25 class As5048Spi
JSpikker 0:3edcf58e51e7 26 {
JSpikker 0:3edcf58e51e7 27 public:
JSpikker 0:3edcf58e51e7 28 As5048Spi(PinName mosi, PinName miso, PinName sclk, PinName chipselect, int nDevices = 1);
JSpikker 0:3edcf58e51e7 29 ~As5048Spi();
JSpikker 0:3edcf58e51e7 30
JSpikker 0:3edcf58e51e7 31 bool error(int device = -1);
JSpikker 0:3edcf58e51e7 32 void frequency(int frequency = 1000000);
JSpikker 0:3edcf58e51e7 33 const int* read(As5048Command command);
JSpikker 0:3edcf58e51e7 34 const int* read_sequential(As5048Command command);
JSpikker 0:3edcf58e51e7 35
JSpikker 2:2958500883e0 36 /// Performs a single angle measurement on all sensors
JSpikker 2:2958500883e0 37 /// @return Array of raw angle data. To get the 14-bit value representing
JSpikker 2:2958500883e0 38 /// the angle, apply the mask() to the result.
JSpikker 2:2958500883e0 39 /// To get an angle in degrees divide 360 by the result of the call to mask().
JSpikker 0:3edcf58e51e7 40 const int* read_angle();
JSpikker 2:2958500883e0 41
JSpikker 2:2958500883e0 42 /// Performs sequential angle measurements on all sensors. The first time this
JSpikker 2:2958500883e0 43 /// method is called the result is not usefull, the measurement data of the call
JSpikker 2:2958500883e0 44 /// will be returned by the next call to this method.
JSpikker 2:2958500883e0 45 /// @return Array of raw angle data. To get the 14-bit value representing
JSpikker 2:2958500883e0 46 /// the angle, apply the mask() to the result.
JSpikker 2:2958500883e0 47 /// To get an angle in degrees divide 360 by the result of the call to mask().
JSpikker 0:3edcf58e51e7 48 const int* read_angle_sequential();
JSpikker 0:3edcf58e51e7 49
JSpikker 2:2958500883e0 50 /// Returns lowest 14-bits
JSpikker 0:3edcf58e51e7 51 static int mask(int sensor_result);
JSpikker 2:2958500883e0 52 static void mask(int* sensor_results, int n);
JSpikker 2:2958500883e0 53 /// Checks if the return value from the sensor has the right parity
JSpikker 2:2958500883e0 54 /// @return true if ok
JSpikker 0:3edcf58e51e7 55 static bool parity_check(int sensor_result);
JSpikker 0:3edcf58e51e7 56 static int degrees(int sensor_result);
JSpikker 0:3edcf58e51e7 57 static int radian(int sensor_result);
JSpikker 0:3edcf58e51e7 58
JSpikker 0:3edcf58e51e7 59
JSpikker 0:3edcf58e51e7 60 protected:
JSpikker 0:3edcf58e51e7 61 int _nDevices;
JSpikker 0:3edcf58e51e7 62 DigitalOut _chipSelectN;
JSpikker 0:3edcf58e51e7 63 SPI _spi;
JSpikker 0:3edcf58e51e7 64
JSpikker 0:3edcf58e51e7 65 int* _readBuffer; // Stores the results of the last sequential read
JSpikker 0:3edcf58e51e7 66
JSpikker 0:3edcf58e51e7 67 int* _read(As5048Command command);
JSpikker 0:3edcf58e51e7 68 };
JSpikker 0:3edcf58e51e7 69