ELEC2645 (2015/16) / SRF02

ELEC 2645 Dogukan Kamacioglu 200792949

Fork of SRF02 by Craig Evans

SRF02.cpp@2:bb52fa779a57, 2016-05-05 (annotated)

Committer:
fy13dk
Date:
Thu May 05 11:48:40 2016 +0000
Revision:
2:bb52fa779a57
Parent:
0:b729d2ce03bd 
Dogukan_K 1.0 w/ Inches

Who changed what in which revision?

UserRevisionLine numberNew contents of line
eencae 0:b729d2ce03bd 1 /**
eencae 0:b729d2ce03bd 2 @file SRF02.cpp
eencae 0:b729d2ce03bd 3
eencae 0:b729d2ce03bd 4 @brief Member functions implementations
eencae 0:b729d2ce03bd 5
eencae 0:b729d2ce03bd 6 */
eencae 0:b729d2ce03bd 7 #include "mbed.h"
eencae 0:b729d2ce03bd 8 #include "SRF02.h"
eencae 0:b729d2ce03bd 9
eencae 0:b729d2ce03bd 10 SRF02::SRF02(PinName sdaPin, PinName sclPin)
eencae 0:b729d2ce03bd 11 {
eencae 0:b729d2ce03bd 12 i2c = new I2C(sdaPin,sclPin); // create new I2C instance and initialise
eencae 0:b729d2ce03bd 13 i2c->frequency(400000); // I2C Fast Mode - 400kHz
eencae 0:b729d2ce03bd 14 leds = new BusOut(LED4,LED3,LED2,LED1);
eencae 0:b729d2ce03bd 15
eencae 0:b729d2ce03bd 16 }
eencae 0:b729d2ce03bd 17
eencae 0:b729d2ce03bd 18 int SRF02::getDistanceCm()
eencae 0:b729d2ce03bd 19 {
eencae 0:b729d2ce03bd 20 char data[2];
eencae 0:b729d2ce03bd 21
eencae 0:b729d2ce03bd 22 // need to send CM command to command register
eencae 0:b729d2ce03bd 23 data[0] = CMD_REG;
eencae 0:b729d2ce03bd 24 data[1] = CM_CMD;
eencae 0:b729d2ce03bd 25 int ack = i2c->write(SRF02_W_ADD,data,2);
eencae 0:b729d2ce03bd 26 if (ack)
eencae 0:b729d2ce03bd 27 error(); // if we don't receive acknowledgement, flash error message
eencae 0:b729d2ce03bd 28
eencae 0:b729d2ce03bd 29 // this will start the sensor ranging, the datasheet suggests a delay of at least 65 ms before reading the result
eencae 0:b729d2ce03bd 30 wait_ms(70);
eencae 0:b729d2ce03bd 31
eencae 0:b729d2ce03bd 32 // we can now read the result - tell the sensor we want the high byte
eencae 0:b729d2ce03bd 33 char reg = RANGE_H_REG;
eencae 0:b729d2ce03bd 34 ack = i2c->write(SRF02_W_ADD,&reg,1);
eencae 0:b729d2ce03bd 35 if (ack)
eencae 0:b729d2ce03bd 36 error(); // if we don't receive acknowledgement, flash error message
eencae 0:b729d2ce03bd 37
eencae 0:b729d2ce03bd 38 // if we read two bytes, the register is automatically incremented (H and L)
eencae 0:b729d2ce03bd 39 ack = i2c->read(SRF02_R_ADD,data,2);
eencae 0:b729d2ce03bd 40 if (ack)
eencae 0:b729d2ce03bd 41 error(); // if we don't receive acknowledgement, flash error message
eencae 0:b729d2ce03bd 42
eencae 0:b729d2ce03bd 43 // high byte is first, then low byte, so combine into 16-bit value
eencae 0:b729d2ce03bd 44 return (data[0] << 8) | data[1];
eencae 0:b729d2ce03bd 45 }
fy13dk 2:bb52fa779a57 46 int SRF02::getDistanceIn()
fy13dk 2:bb52fa779a57 47 {
fy13dk 2:bb52fa779a57 48 char data[2];
fy13dk 2:bb52fa779a57 49
fy13dk 2:bb52fa779a57 50 // need to send CM command to command register
fy13dk 2:bb52fa779a57 51 data[0] = CMD_REG;
fy13dk 2:bb52fa779a57 52 data[1] = INCH_CMD;
fy13dk 2:bb52fa779a57 53 int ack = i2c->write(SRF02_W_ADD,data,2);
fy13dk 2:bb52fa779a57 54 if (ack)
fy13dk 2:bb52fa779a57 55 error(); // if we don't receive acknowledgement, flash error message
fy13dk 2:bb52fa779a57 56
fy13dk 2:bb52fa779a57 57 // this will start the sensor ranging, the datasheet suggests a delay of at least 65 ms before reading the result
fy13dk 2:bb52fa779a57 58 wait_ms(70);
fy13dk 2:bb52fa779a57 59
fy13dk 2:bb52fa779a57 60 // we can now read the result - tell the sensor we want the high byte
fy13dk 2:bb52fa779a57 61 char reg = RANGE_H_REG;
fy13dk 2:bb52fa779a57 62 ack = i2c->write(SRF02_W_ADD,&reg,1);
fy13dk 2:bb52fa779a57 63 if (ack)
fy13dk 2:bb52fa779a57 64 error(); // if we don't receive acknowledgement, flash error message
fy13dk 2:bb52fa779a57 65
fy13dk 2:bb52fa779a57 66 // if we read two bytes, the register is automatically incremented (H and L)
fy13dk 2:bb52fa779a57 67 ack = i2c->read(SRF02_R_ADD,data,2);
fy13dk 2:bb52fa779a57 68 if (ack)
fy13dk 2:bb52fa779a57 69 error(); // if we don't receive acknowledgement, flash error message
fy13dk 2:bb52fa779a57 70
fy13dk 2:bb52fa779a57 71 // high byte is first, then low byte, so combine into 16-bit value
fy13dk 2:bb52fa779a57 72 return (data[0] << 8) | data[1];
fy13dk 2:bb52fa779a57 73 }
fy13dk 2:bb52fa779a57 74
eencae 0:b729d2ce03bd 75 void SRF02::error()
eencae 0:b729d2ce03bd 76 {
eencae 0:b729d2ce03bd 77 while(1) {
eencae 0:b729d2ce03bd 78 leds->write(15);
eencae 0:b729d2ce03bd 79 wait(0.1);
eencae 0:b729d2ce03bd 80 leds->write(0);
eencae 0:b729d2ce03bd 81 wait(0.1);
eencae 0:b729d2ce03bd 82 }
eencae 0:b729d2ce03bd 83 }