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Fork of HCSR04 by
HCSR04.cpp@0:0bda99bb39a4, 2011-10-18 (annotated)
- Committer:
- aralshukaili
- Date:
- Tue Oct 18 14:32:12 2011 +0000
- Revision:
- 0:0bda99bb39a4
- Child:
- 1:d388301a0227
1.0
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
aralshukaili | 0:0bda99bb39a4 | 1 | #include "HCSR04.h" |
aralshukaili | 0:0bda99bb39a4 | 2 | #include "mbed.h" |
aralshukaili | 0:0bda99bb39a4 | 3 | |
aralshukaili | 0:0bda99bb39a4 | 4 | |
aralshukaili | 0:0bda99bb39a4 | 5 | HCSR04::HCSR04(PinName t, PinName e) : trig(t), echo(e) {} |
aralshukaili | 0:0bda99bb39a4 | 6 | |
aralshukaili | 0:0bda99bb39a4 | 7 | // Trigger Echo |
aralshukaili | 0:0bda99bb39a4 | 8 | // _______ _____________,,,,,,,,, |
aralshukaili | 0:0bda99bb39a4 | 9 | // ____| 10us |_________| 150us-25ms, or 38ms if no obstacle |
aralshukaili | 0:0bda99bb39a4 | 10 | // |
aralshukaili | 0:0bda99bb39a4 | 11 | |
aralshukaili | 0:0bda99bb39a4 | 12 | //return echo duration in us (refer to digram above) |
aralshukaili | 0:0bda99bb39a4 | 13 | long HCSR04::echo_duration() { |
aralshukaili | 0:0bda99bb39a4 | 14 | timer.reset(); |
aralshukaili | 0:0bda99bb39a4 | 15 | trig = 0; |
aralshukaili | 0:0bda99bb39a4 | 16 | wait_us(2); |
aralshukaili | 0:0bda99bb39a4 | 17 | trig = 1; |
aralshukaili | 0:0bda99bb39a4 | 18 | wait_us(10); |
aralshukaili | 0:0bda99bb39a4 | 19 | trig = 0; |
aralshukaili | 0:0bda99bb39a4 | 20 | while(echo == 0); |
aralshukaili | 0:0bda99bb39a4 | 21 | timer.start(); |
aralshukaili | 0:0bda99bb39a4 | 22 | while(echo == 1); |
aralshukaili | 0:0bda99bb39a4 | 23 | timer.stop(); |
aralshukaili | 0:0bda99bb39a4 | 24 | return timer.read_us(); |
aralshukaili | 0:0bda99bb39a4 | 25 | } |
aralshukaili | 0:0bda99bb39a4 | 26 | |
aralshukaili | 0:0bda99bb39a4 | 27 | //return distance to nearest obstacle or returns -1 |
aralshukaili | 0:0bda99bb39a4 | 28 | //if no obstacle within range |
aralshukaili | 0:0bda99bb39a4 | 29 | //set sys to cm or inch accordingly |
aralshukaili | 0:0bda99bb39a4 | 30 | long HCSR04::distance(int sys){ |
aralshukaili | 0:0bda99bb39a4 | 31 | duration = echo_duration(); |
aralshukaili | 0:0bda99bb39a4 | 32 | if(duration > 30000) |
aralshukaili | 0:0bda99bb39a4 | 33 | return -1; |
aralshukaili | 0:0bda99bb39a4 | 34 | distacne_cm = duration /29 / 2 ; |
aralshukaili | 0:0bda99bb39a4 | 35 | distance_inc = duration / 74 / 2; |
aralshukaili | 0:0bda99bb39a4 | 36 | if (sys) |
aralshukaili | 0:0bda99bb39a4 | 37 | return distacne_cm; |
aralshukaili | 0:0bda99bb39a4 | 38 | else |
aralshukaili | 0:0bda99bb39a4 | 39 | return distance_inc; |
aralshukaili | 0:0bda99bb39a4 | 40 | } |
aralshukaili | 0:0bda99bb39a4 | 41 |