main.cpp

00001 /* Jason Schilling
00002 jschilling22@my.whitworth.edu
00003 1/15/18
00004 Mini Project 6
00005 This program senses one or two taps in sucession and turns on an led if it was one or two taps.
00006 */
00007 #include <mbed.h>
00008 
00009 DigitalOut ss(p14);
00010 SPI acc(p11, p12, p13);  //MOSI, MISO, and SCK
00011 void tapsHappened(void);
00012 DigitalOut led1(LED1);
00013 DigitalOut led2(LED2);
00014 DigitalOut led4(LED4);
00015 InterruptIn tapInterrupt(p5);
00016 Timeout singleTimeout;
00017 Timeout doubleTimeout;
00018 void singleOff(void);
00019 void doubleOff(void);
00020 
00021 int main() {
00022     ss = 1; // turns off the accelerometer(ADXL345) while setting format and frequency
00023     acc.format(8,3); // 8 bit words, mode 3
00024     acc.frequency(2000000); // 2 MHz clock
00025     // the ADXL345 is turned on for each transmission (and off after each transmission) to adjust its settings
00026     /* for all of the setting adjustments, the first line is the address of the register.
00027     The second line adjusts the setting to the desired value */
00028     ss = 0; 
00029     acc.write(0x1D); // sets tap threshold to 5g
00030     acc.write(80);
00031     ss = 1;
00032     
00033     ss = 0;
00034     acc.write(0x21); // sets tap duration to
00035     acc.write(0x10);    // 10 ms
00036     ss = 1;
00037 
00038     ss = 0;
00039     acc.write(0x22); // sets double tap gap to
00040     acc.write(0x05);    // 6 ms
00041     ss = 1;
00042 
00043     ss = 0;
00044     acc.write(0x23); // sets double tap window to 
00045     acc.write(0xFF);    // 318.75 ms
00046     ss = 1;
00047 
00048     ss = 0;
00049     acc.write(0x2A); // sets tap axes to enable the 
00050     acc.write(0x07); // x, y, and z axes for tap detection
00051     ss = 1;
00052 
00053     ss = 0;
00054     acc.write(0x2E); // sets interrupt enable just to
00055     acc.write(0x60); // single/double taps
00056     ss = 1;
00057 
00058     ss = 0;
00059     acc.write(0x2F); // sets interrupt map to set INT2 high if either a 
00060     acc.write(0x60); // single or double tap interrupt is detected
00061     ss = 1;
00062 
00063     ss = 0;
00064     acc.write(0x2D); // sets power control to
00065     acc.write(0x08); // measure mode
00066     ss = 1;
00067 
00068     wait(0.5);
00069     tapInterrupt.rise(&tapsHappened);
00070     tapsHappened(); // the interrupt is high before getting to this line and will remain high before it is read again, 
00071                     // this line reads it and sets it back to low allowing the program to continue working
00072     while (true) {
00073         led4 = !led4; // led4 flashes to show prgram is running
00074         wait(0.3);
00075     }
00076 }
00077 
00078 void tapsHappened(void) {
00079     char tapByte;
00080     ss = 0;
00081     acc.write(0x30 | 0x80); // 0x30 is the address, 0x80 means we are reading it
00082     tapByte = acc.write(0); // write zero to get a read response (could send anything). tapByte is set equal to this response
00083     ss = 1;
00084 
00085     if (tapByte & 0x40) { 
00086         /* 0x40 converted to binary is a single tap. If there is a single tap, 
00087         it turns on LED 1 and activates the singleOff function one second later */
00088         led1 = 1;
00089         singleTimeout.attach(&singleOff, 1.0);
00090     }
00091     if (tapByte & 0x20) { /* 0x20 converted to binary is a double tap. If there is a double tap, 
00092         it turns on LED 2 and activates the doubleOff function one second later. 
00093         This will turn on LED 1 and 2 because every double tap starts with a single tap */
00094         led2 = 1;
00095         doubleTimeout.attach(&doubleOff, 1.0);
00096     }
00097 }
00098 void singleOff(void) {
00099     // first LED off when this function is called by the timeout
00100     led1 = 0;
00101 }
00102 void doubleOff(void) {
00103     // first LED off when this function is called by the timeout
00104     led2 = 0;
00105 }