Rob Toulson / Mbed 2 deprecated PE_13-01_CompassSetup

by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Dependencies:   mbed

main.cpp@0:1270e200bd76, 2013-06-16 (annotated)

Committer:
robt
Date:
Sun Jun 16 15:37:30 2013 +0000
Revision:
0:1270e200bd76
by Rob Toulson and Tim Wilmshurst from textbook "Fast and Effective Embedded Systems Design: Applying the ARM mbed"

Who changed what in which revision?

UserRevisionLine numberNew contents of line
robt 0:1270e200bd76 1 /* Program Example 13.1: HMC6352 Compass Setup and Read
robt 0:1270e200bd76 2 */
robt 0:1270e200bd76 3 #include "mbed.h"
robt 0:1270e200bd76 4 // mbed objects
robt 0:1270e200bd76 5 I2C compass(p28, p27); // sda, scl
robt 0:1270e200bd76 6 Serial pc(USBTX, USBRX); // tx, rx
robt 0:1270e200bd76 7 // variables
robt 0:1270e200bd76 8 const int addr = 0x42; // define the I2C write Address
robt 0:1270e200bd76 9 char cmd[3]; // command array for read and write
robt 0:1270e200bd76 10 float pos; // measured position
robt 0:1270e200bd76 11
robt 0:1270e200bd76 12 // main code
robt 0:1270e200bd76 13 int main() {
robt 0:1270e200bd76 14 cmd[0] = 0x47; // 'G' write to RAM address
robt 0:1270e200bd76 15 cmd[1] = 0x74; // Operation mode register address
robt 0:1270e200bd76 16 cmd[2] = 0x72; // Op mode = 20H, no S/R, continuous
robt 0:1270e200bd76 17 compass.write(addr,cmd, 3); // Send operation
robt 0:1270e200bd76 18 while (1) {
robt 0:1270e200bd76 19 compass.read(addr, cmd, 2); // read the two-byte echo result
robt 0:1270e200bd76 20 pos = 0.1 * ((cmd[0] << 8) + cmd[1]); //convert to degrees
robt 0:1270e200bd76 21 if (pos>180){
robt 0:1270e200bd76 22 pos=pos-360;
robt 0:1270e200bd76 23 }
robt 0:1270e200bd76 24 pc.printf("deg = %.1f\n", pos);
robt 0:1270e200bd76 25 wait(0.3);
robt 0:1270e200bd76 26 }
robt 0:1270e200bd76 27 }
robt 0:1270e200bd76 28