Rev 2051 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 1612 | dongfang | 1 | #include <avr/io.h> |
| 2 | #include <stdlib.h> |
||
| 3 | #include <inttypes.h> |
||
| 4 | #include "timer0.h" |
||
| 2052 | - | 5 | #include "output.h" |
| 1612 | dongfang | 6 | #include "eeprom.h" |
| 7 | #include "mk3mag.h" |
||
| 8 | |||
| 9 | uint8_t PWMTimeout = 12; |
||
| 2051 | - | 10 | // This will updated in interrupt handler. Should not be processed by main, other than just atomic copy. |
| 11 | volatile uint16_t volatileMagneticHeading; |
||
| 1969 | - | 12 | ToMk3Mag_t toMk3Mag; |
| 1612 | dongfang | 13 | |
| 14 | /*********************************************/ |
||
| 15 | /* Initialize Interface to MK3MAG Compass */ |
||
| 16 | /*********************************************/ |
||
| 2039 | - | 17 | void MK3MAG_init(void) { |
| 1801 | - | 18 | // Port PC4 connected to PWM output from compass module |
| 19 | DDRC &= ~(1 << DDC4); // set as input |
||
| 20 | PORTC |= (1 << PORTC4); // pull up to increase PWM counter also if nothing is connected |
||
| 21 | PWMTimeout = 0; |
||
| 2039 | - | 22 | toMk3Mag.calState = 0; |
| 23 | toMk3Mag.orientation = 1; |
||
| 1612 | dongfang | 24 | } |
| 25 | |||
| 26 | /*********************************************/ |
||
| 27 | /* Get PWM from MK3MAG */ |
||
| 28 | /*********************************************/ |
||
| 2039 | - | 29 | void MK3MAG_periodicTask(void) {// called every 102.4 us by timer 0 ISR |
| 1801 | - | 30 | static uint16_t PWMCount = 0; |
| 1887 | - | 31 | static uint16_t beepDelay = 0; |
| 2041 | - | 32 | // static uint16_t debugCounter = 0; |
| 1801 | - | 33 | // The pulse width varies from 1ms (0°) to 36.99ms (359.9°) |
| 34 | // in other words 100us/° with a +1ms offset. |
||
| 35 | // The signal goes low for 65ms between pulses, |
||
| 36 | // so the cycle time is 65mS + the pulse width. |
||
| 37 | // pwm is high |
||
| 1612 | dongfang | 38 | |
| 2041 | - | 39 | // if (debugCounter++ == 5000) { |
| 40 | // DebugOut.Digital[0] ^= DEBUG_MK3MAG; |
||
| 41 | // debugCounter = 0; |
||
| 42 | // } |
||
| 1805 | - | 43 | |
| 1801 | - | 44 | if (PINC & (1 << PINC4)) { |
| 45 | // If PWM signal is high increment PWM high counter |
||
| 46 | // This counter is incremented by a periode of 102.4us, |
||
| 47 | // i.e. the resoluton of pwm coded heading is approx. 1 deg. |
||
| 48 | PWMCount++; |
||
| 49 | // pwm overflow? |
||
| 50 | if (PWMCount > 400) { |
||
| 51 | if (PWMTimeout) |
||
| 52 | PWMTimeout--; // decrement timeout |
||
| 2051 | - | 53 | volatileMagneticHeading = -1; // unknown heading |
| 1801 | - | 54 | PWMCount = 0; // reset PWM Counter |
| 55 | } |
||
| 56 | } else { // pwm is low |
||
| 1805 | - | 57 | // ignore pwm values values of 0 and higher than 37 ms; |
| 1801 | - | 58 | if ((PWMCount) && (PWMCount < 362)) { // 362 * 102.4us = 37.0688 ms |
| 59 | if (PWMCount < 10) |
||
| 2051 | - | 60 | volatileMagneticHeading = 0; |
| 1805 | - | 61 | else { |
| 2051 | - | 62 | volatileMagneticHeading = ((uint32_t) (PWMCount - 10) * 1049L) / 1024; // correct timebase and offset |
| 1845 | - | 63 | //DebugOut.Digital[1] ^= DEBUG_MK3MAG; // correct signal recd. |
| 1805 | - | 64 | } |
| 65 | /* |
||
| 66 | compassHeading - compassCourse on a -180..179 range. |
||
| 67 | compassHeading 20 compassCourse 30 --> ((540 - 10)%360) - 180 = -10 |
||
| 68 | compassHeading 30 compassCourse 20 --> ((540 + 10)%360) - 180 = 10 |
||
| 69 | compassHeading 350 compassCourse 10 --> ((540 + 340)%360) - 180 = -20 |
||
| 70 | compassHeading 10 compassCourse 350 --> ((540 - 340)%360) - 180 = 20 |
||
| 71 | */ |
||
| 72 | //compassOffCourse = ((540 + compassHeading - compassCourse) % 360) - 180; |
||
| 1801 | - | 73 | PWMTimeout = 12; // if 12 periodes long no valid PWM was detected the data are invalid |
| 74 | // 12 * 362 counts * 102.4 us |
||
| 75 | } |
||
| 76 | PWMCount = 0; // reset pwm counter |
||
| 1805 | - | 77 | } |
| 2041 | - | 78 | |
| 1805 | - | 79 | if (!PWMTimeout) { |
| 1887 | - | 80 | if (checkDelay(beepDelay)) { |
| 81 | if (!beepTime) |
||
| 2044 | - | 82 | beep(50); // make noise with 10Hz to signal the compass problem |
| 1887 | - | 83 | beepDelay = setDelay(100); |
| 1801 | - | 84 | } |
| 1612 | dongfang | 85 | } |
| 86 | } |
||
| 87 |