| 0,0 → 1,88 |
|---|
| #include <avr/io.h> |
| #include <stdlib.h> |
| #include <inttypes.h> |
| #include "timer0.h" |
| #include "uart.h" |
| #include "fc.h" |
| #include "rc.h" |
| #include "eeprom.h" |
| #include "mk3mag.h" |
| |
| uint8_t PWMTimeout = 12; |
| ToMk3Mag_t ToMk3Mag; |
| |
| |
| /*********************************************/ |
| /* Initialize Interface to MK3MAG Compass */ |
| /*********************************************/ |
| void MK3MAG_Init(void) |
| { |
| // Port PC4 connected to PWM output from compass module |
| DDRC &= ~(1<<DDC4); // set as input |
| PORTC |= (1<<PORTC4); // pull up to increase PWM counter also if nothing is connected |
| |
| PWMTimeout = 0; |
| |
| ToMk3Mag.CalState = 0; |
| ToMk3Mag.Orientation = 1; |
| } |
| |
| |
| /*********************************************/ |
| /* Get PWM from MK3MAG */ |
| /*********************************************/ |
| void MK3MAG_Update(void) // called every 102.4 us by timer 0 ISR |
| { |
| static uint16_t PWMCount = 0; |
| static uint16_t BeepDelay = 0; |
| // The pulse width varies from 1ms (0°) to 36.99ms (359.9°) |
| // in other words 100us/° with a +1ms offset. |
| // The signal goes low for 65ms between pulses, |
| // so the cycle time is 65mS + the pulse width. |
| |
| // pwm is high |
| if(PINC & (1<<PINC4)) |
| { // If PWM signal is high increment PWM high counter |
| // This counter is incremented by a periode of 102.4us, |
| // i.e. the resoluton of pwm coded heading is approx. 1 deg. |
| PWMCount++; |
| // pwm overflow? |
| if (PWMCount > 400) |
| { |
| if(PWMTimeout) PWMTimeout--; // decrement timeout |
| CompassHeading = -1; // unknown heading |
| PWMCount = 0; // reset PWM Counter |
| } |
| |
| } |
| else // pwm is low |
| { // ignore pwm values values of 0 and higher than 37 ms |
| if((PWMCount) && (PWMCount < 362)) // 362 * 102.4us = 37.0688 ms |
| { |
| if(PWMCount <10) CompassHeading = 0; |
| else CompassHeading = ((uint32_t)(PWMCount - 10) * 1049L)/1024; // correct timebase and offset |
| CompassOffCourse = ((540 + CompassHeading - CompassCourse) % 360) - 180; |
| PWMTimeout = 12; // if 12 periodes long no valid PWM was detected the data are invalid |
| // 12 * 362 counts * 102.4 us |
| } |
| else |
| { // bad pwm value (out of range or permanent low) |
| if(PWMTimeout) PWMTimeout--; // decrement timeout |
| CompassHeading = -1; // unknown heading |
| CompassOffCourse = 0; |
| } |
| PWMCount = 0; // reset pwm counter |
| } |
| |
| if(!PWMTimeout) |
| { |
| if(CheckDelay(BeepDelay)) |
| { |
| if(!BeepTime) BeepTime = 100; // make noise with 10Hz to signal the compass problem |
| BeepDelay = SetDelay(100); |
| } |
| } |
| } |
| |
| |
| |