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 Sep 18 10:20:22 2014 +0000
Revision:
0:3edcf58e51e7
Child:
2:2958500883e0
Version 0.3: reads single sensor value, 10000 samples speed test at 10MHz SPI, writes data to local storage

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 0:3edcf58e51e7 16
JSpikker 0:3edcf58e51e7 17
JSpikker 0:3edcf58e51e7 18 class As5048Spi
JSpikker 0:3edcf58e51e7 19 {
JSpikker 0:3edcf58e51e7 20 public:
JSpikker 0:3edcf58e51e7 21 As5048Spi(PinName mosi, PinName miso, PinName sclk, PinName chipselect, int nDevices = 1);
JSpikker 0:3edcf58e51e7 22 ~As5048Spi();
JSpikker 0:3edcf58e51e7 23
JSpikker 0:3edcf58e51e7 24 bool error(int device = -1);
JSpikker 0:3edcf58e51e7 25 void frequency(int frequency = 1000000);
JSpikker 0:3edcf58e51e7 26 const int* read(As5048Command command);
JSpikker 0:3edcf58e51e7 27 const int* read_sequential(As5048Command command);
JSpikker 0:3edcf58e51e7 28
JSpikker 0:3edcf58e51e7 29 const int* read_angle();
JSpikker 0:3edcf58e51e7 30 const int* read_angle_sequential();
JSpikker 0:3edcf58e51e7 31
JSpikker 0:3edcf58e51e7 32
JSpikker 0:3edcf58e51e7 33 static int mask(int sensor_result);
JSpikker 0:3edcf58e51e7 34
JSpikker 0:3edcf58e51e7 35 static bool parity_check(int sensor_result);
JSpikker 0:3edcf58e51e7 36 static int degrees(int sensor_result);
JSpikker 0:3edcf58e51e7 37 static int radian(int sensor_result);
JSpikker 0:3edcf58e51e7 38
JSpikker 0:3edcf58e51e7 39
JSpikker 0:3edcf58e51e7 40 protected:
JSpikker 0:3edcf58e51e7 41 int _nDevices;
JSpikker 0:3edcf58e51e7 42 DigitalOut _chipSelectN;
JSpikker 0:3edcf58e51e7 43 SPI _spi;
JSpikker 0:3edcf58e51e7 44
JSpikker 0:3edcf58e51e7 45 int* _readBuffer; // Stores the results of the last sequential read
JSpikker 0:3edcf58e51e7 46
JSpikker 0:3edcf58e51e7 47 int* _read(As5048Command command);
JSpikker 0:3edcf58e51e7 48 };
JSpikker 0:3edcf58e51e7 49