William Lange / Mbed 2 deprecated DistanceFirmware

Same as mallet... but distance

Dependencies:   EthernetInterface NetworkAPI mbed-rtos mbed

Fork of MalletFirmware by Impact-Echo

AngleEncoder.cpp@30:1da0bb9c31a6, 2014-12-09 (annotated)

Committer:
willange
Date:
Tue Dec 09 17:37:12 2014 +0000
Revision:
30:1da0bb9c31a6
Parent:
22:523e316cbe70 
a basic timer

Who changed what in which revision?

UserRevisionLine numberNew contents of line
timmey9 22:523e316cbe70 1 #include "AngleEncoder.h"
timmey9 22:523e316cbe70 2 #include "mbed.h"
timmey9 22:523e316cbe70 3
timmey9 22:523e316cbe70 4 AngleEncoder::AngleEncoder(PinName mosi, PinName miso, PinName sclk, PinName cs, int bits, int mode, int hz) :
timmey9 22:523e316cbe70 5 _spi(mosi, miso, sclk),
timmey9 22:523e316cbe70 6 _cs(cs) {
timmey9 22:523e316cbe70 7 // constructor
timmey9 22:523e316cbe70 8 _cs = 1;
timmey9 22:523e316cbe70 9 _spi.format(bits,mode);
timmey9 22:523e316cbe70 10 _spi.frequency(hz);
timmey9 22:523e316cbe70 11
timmey9 22:523e316cbe70 12 wait_ms(1000); // Angle encoder requires 0.1 seconds to boot up, so I gave it an entire second.
timmey9 22:523e316cbe70 13
timmey9 22:523e316cbe70 14 }
timmey9 22:523e316cbe70 15
timmey9 22:523e316cbe70 16
timmey9 22:523e316cbe70 17
timmey9 22:523e316cbe70 18 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
timmey9 22:523e316cbe70 19 *
timmey9 22:523e316cbe70 20 * Sends a NOP command. This is a read command.
timmey9 22:523e316cbe70 21 *
timmey9 22:523e316cbe70 22 * Returns the 8 bit data read from the encoder.
timmey9 22:523e316cbe70 23 * 0xA5 indicates communication is good, but no data to receive from encoder
timmey9 22:523e316cbe70 24 *
timmey9 22:523e316cbe70 25 * 0x00 indicates that angle encoder probably wasn't read. May need to
timmey9 22:523e316cbe70 26 * increase SPI_DELAY
timmey9 22:523e316cbe70 27 *
timmey9 22:523e316cbe70 28 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
timmey9 22:523e316cbe70 29 int AngleEncoder::nop() { // this function takes about 90us to complete (tested using Timer library)
timmey9 22:523e316cbe70 30 _cs = 0;
timmey9 22:523e316cbe70 31 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 32 int received = _spi.write(0x00);
timmey9 22:523e316cbe70 33 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 34 _cs = 1;
timmey9 22:523e316cbe70 35 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 36 return received;
timmey9 22:523e316cbe70 37 }
timmey9 22:523e316cbe70 38
timmey9 22:523e316cbe70 39
timmey9 22:523e316cbe70 40 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
timmey9 22:523e316cbe70 41 *
timmey9 22:523e316cbe70 42 * Sets the current position as the zero point from which angles are calculated
timmey9 22:523e316cbe70 43 *
timmey9 22:523e316cbe70 44 * Returns true if successful, false otherwise
timmey9 22:523e316cbe70 45 *
timmey9 22:523e316cbe70 46 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
timmey9 22:523e316cbe70 47 bool AngleEncoder::set_zero() {
timmey9 22:523e316cbe70 48 char received;
timmey9 22:523e316cbe70 49
timmey9 22:523e316cbe70 50 // send "set_zero_point" command
timmey9 22:523e316cbe70 51 _cs = 0;
timmey9 22:523e316cbe70 52 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 53 received = _spi.write(0x70); // send the command
timmey9 22:523e316cbe70 54 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 55 _cs = 1;
timmey9 22:523e316cbe70 56 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 57
timmey9 22:523e316cbe70 58 // send NOP until reset is confirmed
timmey9 22:523e316cbe70 59 while(received == 0xa5) received = nop();
timmey9 22:523e316cbe70 60
timmey9 22:523e316cbe70 61 // 0x80 indicates that reset is confirmed
timmey9 22:523e316cbe70 62 if(received == 0x80) return true;
timmey9 22:523e316cbe70 63 else return false;
timmey9 22:523e316cbe70 64 }
timmey9 22:523e316cbe70 65
timmey9 22:523e316cbe70 66
timmey9 22:523e316cbe70 67 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
timmey9 22:523e316cbe70 68 *
timmey9 22:523e316cbe70 69 * Sets the current position as the zero point from which angles are calculated
timmey9 22:523e316cbe70 70 * @param rotary_count The address to the rotary_count variable, allowing this
timmey9 22:523e316cbe70 71 * function to reset both the absolute and relative angles.
timmey9 22:523e316cbe70 72 *
timmey9 22:523e316cbe70 73 * Returns true if successful, false otherwise
timmey9 22:523e316cbe70 74 *
timmey9 22:523e316cbe70 75 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
timmey9 22:523e316cbe70 76 bool AngleEncoder::set_zero(int* rotary_count) {
timmey9 22:523e316cbe70 77
timmey9 22:523e316cbe70 78 *rotary_count = 0; // reset relative counter
timmey9 22:523e316cbe70 79 return set_zero(); // reset absolute counter
timmey9 22:523e316cbe70 80 }
timmey9 22:523e316cbe70 81
timmey9 22:523e316cbe70 82
timmey9 22:523e316cbe70 83 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
timmey9 22:523e316cbe70 84 *
timmey9 22:523e316cbe70 85 * Reads the absolute angle from the angle encoder via SPI
timmey9 22:523e316cbe70 86 * Returns the 12 bit angle (-2048, 2047)
timmey9 22:523e316cbe70 87 *
timmey9 22:523e316cbe70 88 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
timmey9 22:523e316cbe70 89 int AngleEncoder::absolute_angle() { // this function takes about 500us to complete (tested using Timer library)
timmey9 22:523e316cbe70 90 char received;
timmey9 22:523e316cbe70 91 uint16_t absolute_pos;
timmey9 22:523e316cbe70 92
timmey9 22:523e316cbe70 93 // send read command
timmey9 22:523e316cbe70 94 _cs = 0;
timmey9 22:523e316cbe70 95 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 96 received = _spi.write(0x10);
timmey9 22:523e316cbe70 97 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 98 _cs = 1;
timmey9 22:523e316cbe70 99
timmey9 22:523e316cbe70 100 // wait for angle encoder to echo the command
timmey9 22:523e316cbe70 101 wait_us(SPI_DELAY);
timmey9 22:523e316cbe70 102
timmey9 22:523e316cbe70 103 // read until encoder sends 0x10
timmey9 22:523e316cbe70 104 for(uint32_t i = 0; i < 100; i++)
timmey9 22:523e316cbe70 105 {
timmey9 22:523e316cbe70 106 received = nop();
timmey9 22:523e316cbe70 107 if(received == 0x10) break;
timmey9 22:523e316cbe70 108 }
timmey9 22:523e316cbe70 109
timmey9 22:523e316cbe70 110 //while(received != 0x10) received = nop(); // read until 0x10 is received
timmey9 22:523e316cbe70 111
timmey9 22:523e316cbe70 112 // the command should have been echoed back. If so, then read the angle
timmey9 22:523e316cbe70 113 if(received == 0x10)
timmey9 22:523e316cbe70 114 {
timmey9 22:523e316cbe70 115 // receive the most significatn 4 bits of the 12 bit angle
timmey9 22:523e316cbe70 116 absolute_pos = nop(); // read first 4 bits of absolute angle
timmey9 22:523e316cbe70 117 absolute_pos <<= 8; // shift the 4 bits into the right spot
timmey9 22:523e316cbe70 118 absolute_pos |= nop(); // receive the last 8 bits of absolute angle
timmey9 22:523e316cbe70 119
timmey9 22:523e316cbe70 120 //make data symmetric around 0.
timmey9 22:523e316cbe70 121 //if(absolute_pos > 2048) absolute_pos -= 4096;
timmey9 22:523e316cbe70 122 //absolute_pos = ~absolute_pos + 1; // inverts the data
timmey9 22:523e316cbe70 123 return absolute_pos;
timmey9 22:523e316cbe70 124 }
timmey9 22:523e316cbe70 125 else return 0x00ff0000; // this is just a random number outside of the range of the encoder
timmey9 22:523e316cbe70 126 }