Rob Toulson / Mbed 2 deprecated PE_07-04_AccelerometerOutput

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

Dependencies:   mbed

main.cpp@0:371be129802f, 2012-10-15 (annotated)

Committer:
robt
Date:
Mon Oct 15 21:25:27 2012 +0000
Revision:
0:371be129802f
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 0:371be129802f 1 /*Program Example 7.4: Reads values from accelerometer through SPI, and outputs
robt 0:371be129802f 2 continuously to terminal screen.
robt 0:371be129802f 3 */
robt 0:371be129802f 4
robt 0:371be129802f 5 #include "mbed.h"
robt 0:371be129802f 6 SPI acc(p11,p12,p13); // set up SPI interface on pins 11,12,13
robt 0:371be129802f 7 DigitalOut cs(p14); // use pin 14 as chip select
robt 0:371be129802f 8 Serial pc(USBTX, USBRX); // set up USB interface to host terminal
robt 0:371be129802f 9 char buffer[6]; //raw data array type char
robt 0:371be129802f 10 int16_t data[3]; // 16-bit twos-complement integer data
robt 0:371be129802f 11 float x, y, z; // floating point data, to be displayed on-screen
robt 0:371be129802f 12
robt 0:371be129802f 13 int main() {
robt 0:371be129802f 14 cs=1; //initially ADXL345 is not activated
robt 0:371be129802f 15 acc.format(8,3); // 8 bit data, Mode 3
robt 0:371be129802f 16 acc.frequency(2000000); // 2MHz clock rate
robt 0:371be129802f 17 cs=0; //select the device
robt 0:371be129802f 18 acc.write(0x31); // data format register
robt 0:371be129802f 19 acc.write(0x0B); // format +/-16g, 0.004g/LSB
robt 0:371be129802f 20 cs=1; //end of transmission
robt 0:371be129802f 21 cs=0; //start a new transmission
robt 0:371be129802f 22 acc.write(0x2D); // power ctrl register
robt 0:371be129802f 23 acc.write(0x08); // measure mode
robt 0:371be129802f 24 cs=1; //end of transmission
robt 0:371be129802f 25 while (1) { // infinite loop
robt 0:371be129802f 26 wait(0.2);
robt 0:371be129802f 27 cs=0; //start a transmission
robt 0:371be129802f 28 acc.write(0x80|0x40|0x32); // RW bit high, MB bit high, plus address
robt 0:371be129802f 29 for (int i = 0;i<=5;i++) {
robt 0:371be129802f 30 buffer[i]=acc.write(0x00); // read back 6 data bytes
robt 0:371be129802f 31 }
robt 0:371be129802f 32 cs=1; //end of transmission
robt 0:371be129802f 33 data[0] = buffer[1]<<8 | buffer[0]; // combine MSB and LSB
robt 0:371be129802f 34 data[1] = buffer[3]<<8 | buffer[2];
robt 0:371be129802f 35 data[2] = buffer[5]<<8 | buffer[4];
robt 0:371be129802f 36 x=0.004*data[0]; y=0.004*data[1]; z=0.004*data[2]; // convert to float,
robt 0:371be129802f 37 //actual g value
robt 0:371be129802f 38 pc.printf("x = %+1.2fg\t y = %+1.2fg\t z = %+1.2fg\n\r", x, y,z); //print
robt 0:371be129802f 39 }
robt 0:371be129802f 40 }
robt 0:371be129802f 41