bicycle_odometer
changeset 4:f883847a0591 tip
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| author | John Tsiombikas <nuclear@member.fsf.org> |
|---|---|
| date | Fri, 26 Aug 2011 06:16:00 +0300 |
| parents | c0c68988bcdf |
| children | |
| files | odometer.c |
| diffstat | 1 files changed, 17 insertions(+), 15 deletions(-) [+] |
line diff
1.1 --- a/odometer.c Thu Aug 25 08:22:19 2011 +0300 1.2 +++ b/odometer.c Fri Aug 26 06:16:00 2011 +0300 1.3 @@ -36,7 +36,8 @@ 1.4 #define PD_DATA_MASK 0xf 1.5 #define PD_LEDS_MASK 0xc0 1.6 1.7 -#define RPS_TO_KMH(x) ((36 * WHEEL_PERIMETER * (x)) / 1000) 1.8 +/* 1800 2sec intervals per hour, \times perimeter, \times x, \over 100000 cm in a kilometer */ 1.9 +#define RP2S_TO_KMH(x) ((18 * WHEEL_PERIMETER * (x)) / 1000) 1.10 1.11 #define DEBOUNCE_TICKS 1 1.12 1.13 @@ -49,7 +50,7 @@ 1.14 1.15 void init_timer(void); 1.16 void latch(int n); 1.17 -void update_display(void); 1.18 +void update_display(int idx); 1.19 void disp_speed(int n); 1.20 void disp_dist(int n); 1.21 void disp_leds(int n); 1.22 @@ -60,7 +61,7 @@ 1.23 volatile long ticks; 1.24 1.25 unsigned long nrot; 1.26 -unsigned long speed_rps; 1.27 +unsigned long speed_rp2s; 1.28 1.29 int main(void) 1.30 { 1.31 @@ -148,28 +149,29 @@ 1.32 if(state) { 1.33 nrot++; 1.34 1.35 - update_display(); 1.36 + /*update_display();*/ 1.37 } 1.38 + prev_time = ticks; 1.39 } 1.40 - 1.41 - prev_time = ticks; 1.42 } 1.43 1.44 ISR(TIMER0_OVF_vect) 1.45 { 1.46 - volatile static int sec_ticks; 1.47 - volatile static unsigned long last_rot; 1.48 + volatile static int sec_ticks, sec; 1.49 + volatile static unsigned long last_rot[4]; 1.50 1.51 ticks++; 1.52 sec_ticks++; 1.53 1.54 - if(sec_ticks >= SEC_TICKS) { 1.55 - speed_rps = nrot - last_rot; 1.56 + if(sec_ticks >= SEC_TICKS / 2) { 1.57 + int idx = ++sec & 3; 1.58 1.59 - update_display(); 1.60 + speed_rp2s = nrot - last_rot[idx]; 1.61 + 1.62 + update_display(idx); 1.63 1.64 sec_ticks = 0; 1.65 - last_rot = nrot; 1.66 + last_rot[idx] = nrot; 1.67 } 1.68 1.69 1.70 @@ -183,11 +185,11 @@ 1.71 } 1.72 } 1.73 1.74 -void update_display(void) 1.75 +void update_display(int idx) 1.76 { 1.77 if(debug_mode) { 1.78 disp_dist(nrot); 1.79 - disp_speed(speed_rps); 1.80 + disp_speed(speed_rp2s); 1.81 1.82 if(state) { 1.83 PORTD |= (1 << 5); 1.84 @@ -196,7 +198,7 @@ 1.85 } 1.86 } else { 1.87 unsigned long dist_cm = (nrot * WHEEL_PERIMETER); 1.88 - int speed_kmh = RPS_TO_KMH(speed_rps); 1.89 + int speed_kmh = RP2S_TO_KMH(speed_rp2s); 1.90 1.91 disp_dist(dist_cm / 10000); 1.92 disp_speed(speed_kmh);