DCS_TEAM / Mbed 2 deprecated Chemical_Sensor_DMA

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Dependencies:   mbed

Dependents:   DCS_FINAL_CODE

Fork of Chemical_Sensor_DMA by Jared Baxter

AngleEncoder.cpp@5:1b2dc43e8947, 2015-11-06 (annotated)

Committer:
baxterja
Date:
Fri Nov 06 19:28:49 2015 +0000
Revision:
5:1b2dc43e8947
Parent:
2:3771b3195c7b 
Dewayne,  Use this one

Who changed what in which revision?

UserRevisionLine numberNew contents of line
baxterja 2:3771b3195c7b 1 #include "AngleEncoder.h"
baxterja 2:3771b3195c7b 2 #include "mbed.h"
baxterja 2:3771b3195c7b 3
baxterja 2:3771b3195c7b 4 AngleEncoder::AngleEncoder(PinName mosi, PinName miso, PinName sclk, PinName cs, int bits, int mode, int hz) :
baxterja 2:3771b3195c7b 5 _spi(mosi, miso, sclk),
baxterja 2:3771b3195c7b 6 _cs(cs) {
baxterja 2:3771b3195c7b 7 // constructor
baxterja 2:3771b3195c7b 8 _cs = 1;
baxterja 2:3771b3195c7b 9 _spi.format(bits,mode);
baxterja 2:3771b3195c7b 10 _spi.frequency(hz);
baxterja 2:3771b3195c7b 11
baxterja 2:3771b3195c7b 12 wait_ms(1000); // Angle encoder requires 0.1 seconds to boot up, so I gave it an entire second.
baxterja 2:3771b3195c7b 13
baxterja 2:3771b3195c7b 14 }
baxterja 2:3771b3195c7b 15
baxterja 2:3771b3195c7b 16
baxterja 2:3771b3195c7b 17
baxterja 2:3771b3195c7b 18 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
baxterja 2:3771b3195c7b 19 *
baxterja 2:3771b3195c7b 20 * Sends a NOP command. This is a read command.
baxterja 2:3771b3195c7b 21 *
baxterja 2:3771b3195c7b 22 * Returns the 8 bit data read from the encoder.
baxterja 2:3771b3195c7b 23 * 0xA5 indicates communication is good, but no data to receive from encoder
baxterja 2:3771b3195c7b 24 *
baxterja 2:3771b3195c7b 25 * 0x00 indicates that angle encoder probably wasn't read. May need to
baxterja 2:3771b3195c7b 26 * increase SPI_DELAY
baxterja 2:3771b3195c7b 27 *
baxterja 2:3771b3195c7b 28 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
baxterja 2:3771b3195c7b 29 int AngleEncoder::nop() { // this function takes about 90us to complete (tested using Timer library)
baxterja 2:3771b3195c7b 30 _cs = 0;
baxterja 2:3771b3195c7b 31 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 32 int received = _spi.write(0x00);
baxterja 2:3771b3195c7b 33 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 34 _cs = 1;
baxterja 2:3771b3195c7b 35 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 36 return received;
baxterja 2:3771b3195c7b 37 }
baxterja 2:3771b3195c7b 38
baxterja 2:3771b3195c7b 39
baxterja 2:3771b3195c7b 40 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
baxterja 2:3771b3195c7b 41 *
baxterja 2:3771b3195c7b 42 * Sets the current position as the zero point from which angles are calculated
baxterja 2:3771b3195c7b 43 *
baxterja 2:3771b3195c7b 44 * Returns true if successful, false otherwise
baxterja 2:3771b3195c7b 45 *
baxterja 2:3771b3195c7b 46 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
baxterja 2:3771b3195c7b 47 bool AngleEncoder::set_zero() {
baxterja 2:3771b3195c7b 48 char received;
baxterja 2:3771b3195c7b 49
baxterja 2:3771b3195c7b 50 // send "set_zero_point" command
baxterja 2:3771b3195c7b 51 _cs = 0;
baxterja 2:3771b3195c7b 52 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 53 received = _spi.write(0x70); // send the command
baxterja 2:3771b3195c7b 54 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 55 _cs = 1;
baxterja 2:3771b3195c7b 56 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 57
baxterja 2:3771b3195c7b 58 // send NOP until reset is confirmed
baxterja 2:3771b3195c7b 59 while(received == 0xa5) received = nop();
baxterja 2:3771b3195c7b 60
baxterja 2:3771b3195c7b 61 // 0x80 indicates that reset is confirmed
baxterja 2:3771b3195c7b 62 if(received == 0x80) return true;
baxterja 2:3771b3195c7b 63 else return false;
baxterja 2:3771b3195c7b 64 }
baxterja 2:3771b3195c7b 65
baxterja 2:3771b3195c7b 66
baxterja 2:3771b3195c7b 67 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
baxterja 2:3771b3195c7b 68 *
baxterja 2:3771b3195c7b 69 * Sets the current position as the zero point from which angles are calculated
baxterja 2:3771b3195c7b 70 * @param rotary_count The address to the rotary_count variable, allowing this
baxterja 2:3771b3195c7b 71 * function to reset both the absolute and relative angles.
baxterja 2:3771b3195c7b 72 *
baxterja 2:3771b3195c7b 73 * Returns true if successful, false otherwise
baxterja 2:3771b3195c7b 74 *
baxterja 2:3771b3195c7b 75 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
baxterja 2:3771b3195c7b 76 bool AngleEncoder::set_zero(int* rotary_count) {
baxterja 2:3771b3195c7b 77
baxterja 2:3771b3195c7b 78 *rotary_count = 0; // reset relative counter
baxterja 2:3771b3195c7b 79 return set_zero(); // reset absolute counter
baxterja 2:3771b3195c7b 80 }
baxterja 2:3771b3195c7b 81
baxterja 2:3771b3195c7b 82
baxterja 2:3771b3195c7b 83 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
baxterja 2:3771b3195c7b 84 *
baxterja 2:3771b3195c7b 85 * Reads the absolute angle from the angle encoder via SPI
baxterja 2:3771b3195c7b 86 * Returns the 12 bit angle (-2048, 2047)
baxterja 2:3771b3195c7b 87 *
baxterja 2:3771b3195c7b 88 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
baxterja 2:3771b3195c7b 89 int AngleEncoder::absolute_angle() { // this function takes about 500us to complete (tested using Timer library)
baxterja 2:3771b3195c7b 90 char received;
baxterja 2:3771b3195c7b 91 uint16_t absolute_pos;
baxterja 2:3771b3195c7b 92
baxterja 2:3771b3195c7b 93 // send read command
baxterja 2:3771b3195c7b 94 _cs = 0;
baxterja 2:3771b3195c7b 95 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 96 received = _spi.write(0x10);
baxterja 2:3771b3195c7b 97 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 98 _cs = 1;
baxterja 2:3771b3195c7b 99
baxterja 2:3771b3195c7b 100 // wait for angle encoder to echo the command
baxterja 2:3771b3195c7b 101 wait_us(SPI_DELAY);
baxterja 2:3771b3195c7b 102
baxterja 2:3771b3195c7b 103 // read until encoder sends 0x10
baxterja 2:3771b3195c7b 104 for(uint32_t i = 0; i < 100; i++)
baxterja 2:3771b3195c7b 105 {
baxterja 2:3771b3195c7b 106 received = nop();
baxterja 2:3771b3195c7b 107 if(received == 0x10) break;
baxterja 2:3771b3195c7b 108 }
baxterja 2:3771b3195c7b 109
baxterja 2:3771b3195c7b 110 //while(received != 0x10) received = nop(); // read until 0x10 is received
baxterja 2:3771b3195c7b 111
baxterja 2:3771b3195c7b 112 // the command should have been echoed back. If so, then read the angle
baxterja 2:3771b3195c7b 113 if(received == 0x10)
baxterja 2:3771b3195c7b 114 {
baxterja 2:3771b3195c7b 115 // receive the most significatn 4 bits of the 12 bit angle
baxterja 2:3771b3195c7b 116 absolute_pos = nop(); // read first 4 bits of absolute angle
baxterja 2:3771b3195c7b 117 absolute_pos <<= 8; // shift the 4 bits into the right spot
baxterja 2:3771b3195c7b 118 absolute_pos |= nop(); // receive the last 8 bits of absolute angle
baxterja 2:3771b3195c7b 119
baxterja 2:3771b3195c7b 120 //make data symmetric around 0.
baxterja 2:3771b3195c7b 121 //if(absolute_pos > 2048) absolute_pos -= 4096;
baxterja 2:3771b3195c7b 122 //absolute_pos = ~absolute_pos + 1; // inverts the data
baxterja 2:3771b3195c7b 123 return absolute_pos;
baxterja 2:3771b3195c7b 124 }
baxterja 2:3771b3195c7b 125 else return 0x00ff0000; // this is just a random number outside of the range of the encoder
baxterja 2:3771b3195c7b 126 }