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Fine-tune data types, optimize while loops

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Rihards Skuja 2018-01-02 19:32:11 +02:00
parent b74f68994d
commit 4f2b6d242a
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GPG Key ID: 53FA13A3F7F8571B
2 changed files with 5 additions and 5 deletions
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4
include/sonar.h
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@ -19,7 +19,7 @@
#define US_PER_CM 58 // Time for sound to travel distance of 1cm #define US_PER_CM 58 // Time for sound to travel distance of 1cm
#define MAX_SONAR_RANGE 8 // Trigger + echo (m) #define MAX_SONAR_RANGE 8 // Trigger + echo (m)
#define DELAY_BETWEEN_TESTS 500 // Timeout for return signal #define DELAY_BETWEEN_TESTS 500 // Timeout for return signal
#define TIMER_MAX 65535 // Depends on the timer used #define TIMER_MAX 65535 // For 16-bit timer
#define CYCLES_PER_US F_CPU / 1000000 #define CYCLES_PER_US F_CPU / 1000000
#define SONAR_TIMEOUT (F_CPU * MAX_SONAR_RANGE) / SPEED_OF_SOUND #define SONAR_TIMEOUT (F_CPU * MAX_SONAR_RANGE) / SPEED_OF_SOUND
@ -30,6 +30,6 @@
void init_sonar(void); void init_sonar(void);
void trigger_sonar(void); void trigger_sonar(void);
int read_sonar(void); int32_t read_sonar(void);
#endif /* SONAR_H */ #endif /* SONAR_H */

6
src/sonar.c
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@ -3,7 +3,7 @@
#include "sonar.h" #include "sonar.h"
volatile uint32_t overflow_counter = 0; volatile uint32_t overflow_counter = 0;
volatile uint32_t trig_counter = 0; volatile uint32_t timeout_val = SONAR_TIMEOUT;
volatile uint32_t no_of_cycles = 0; volatile uint32_t no_of_cycles = 0;
void init_sonar(void) void init_sonar(void)
@ -28,7 +28,7 @@ ISR(TIMER1_OVF_vect)
TCNT1 = 0; TCNT1 = 0;
} }
int read_sonar(void) int32_t read_sonar(void)
{ {
int dist_in_cm = 0; int dist_in_cm = 0;
init_sonar(); init_sonar();
@ -36,7 +36,7 @@ int read_sonar(void)
// While echo pin is low // While echo pin is low
while (!(CHK(ECHO_PIN, ECHO_BIT))) { while (!(CHK(ECHO_PIN, ECHO_BIT))) {
if (++trig_counter > SONAR_TIMEOUT) if (--timeout_val == 0)
return TRIG_ERROR; // Received no response from echo return TRIG_ERROR; // Received no response from echo
} }