Saxion Lectoraat MT / AS5048

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.

Diff: as5048spi.cpp

Revision:
2:2958500883e0
Parent:
1:f2ed22514649
--- a/as5048spi.cpp	Thu Sep 18 19:28:25 2014 +0000
+++ b/as5048spi.cpp	Thu Dec 04 10:00:42 2014 +0000
@@ -59,6 +59,15 @@
     return sensor_result & 0x3FFF; // return lowest 14-bits
 }
 
+
+void As5048Spi::mask(int* sensor_results, int n)
+{
+    for(int i = 0; i < n; ++i) {
+        sensor_results[i] &= 0x3FFF;
+    }
+}
+
+
 bool As5048Spi::parity_check(int sensor_result)
 {
     // Use the LSb of result to keep track of parity (0 = even, 1 = odd)