Satoru Yoshida / Mbed 2 deprecated int555

test interruptIn feature with 555 timer

Dependencies:   ClockControl PowerControl mbed

Fork of Frequency_counter by Satoru Yoshida

Test interruptIn function with using LMC555 timer IC

LPC 1768 自身が持つタイマー割り込み機能を使わずに、 あえて外部のタイマー IC 555 からの信号で周期的に割り込みするテスト。

下記の回路例では、555 の output 端子が 約 10 秒周期のうち、0.3 秒間 Low になるはず。 ただし、コンデンサーおよび抵抗の誤差の影響があり、実測値は約７秒周期

C を 47μ から 330 μ に変えると約１分前後で周期的に割り込みがかかります。

/media/uploads/strysd/int555_10s.png

なるべく配線が交差しないように部品配置してみた例

/media/uploads/strysd/555test.jpg

main.cpp@6:7f90a61e1a69, 2013-08-11 (annotated)

Committer:
strysd
Date:
Sun Aug 11 08:34:00 2013 +0000
Revision:
6:7f90a61e1a69
Parent:
5:9be3080ca8ba
Child:
7:42e7f18361c8
separate defines

Who changed what in which revision?

UserRevisionLine numberNew contents of line
strysd 6:7f90a61e1a69 1 //see mbed.org/users/strysd/notebook/measure_humidity_with_hs15p_and_lmc555/
Neel 0:c5bcf643a8b1 2 #include "mbed.h"
strysd 6:7f90a61e1a69 3 #include "main.h"
strysd 1:e2034bcdb101 4
strysd 4:64d9c0bed75b 5 InterruptIn in(p8); //connect to the Discharge of 555
strysd 5:9be3080ca8ba 6 DigitalOut run555(p9);//connect to the Reset of 555
Neel 0:c5bcf643a8b1 7 DigitalOut led(LED1);
Neel 0:c5bcf643a8b1 8 Timer t1;
Neel 0:c5bcf643a8b1 9
strysd 4:64d9c0bed75b 10 float my_interval = 0;//between interrupts in microseconds
strysd 1:e2034bcdb101 11 float my_freq = 0;//Hz
strysd 4:64d9c0bed75b 12 float my_ohm = 0;//ohm for HS15P
strysd 4:64d9c0bed75b 13 int rest_in = 0;//rest of interrupt times
Neel 0:c5bcf643a8b1 14
Neel 0:c5bcf643a8b1 15 void flip(void)
Neel 0:c5bcf643a8b1 16 {
strysd 6:7f90a61e1a69 17 if(rest_in < READ_TIMER){
strysd 6:7f90a61e1a69 18 my_interval = t1.read_us();// Get time since last interrupt
strysd 4:64d9c0bed75b 19 }
strysd 5:9be3080ca8ba 20
strysd 6:7f90a61e1a69 21 t1.reset();// Reset timer and wait for next interrupt
strysd 6:7f90a61e1a69 22 rest_in--;
strysd 6:7f90a61e1a69 23
strysd 6:7f90a61e1a69 24 if(rest_in <= 0){
strysd 1:e2034bcdb101 25 //No use interrupt
strysd 4:64d9c0bed75b 26 run555 = led = 0;
strysd 1:e2034bcdb101 27 t1.stop();
strysd 1:e2034bcdb101 28 }
Neel 0:c5bcf643a8b1 29 }
Neel 0:c5bcf643a8b1 30
Neel 0:c5bcf643a8b1 31 int main() {
strysd 4:64d9c0bed75b 32 run555 = led = 0;
strysd 5:9be3080ca8ba 33 // Set up the interrupt
strysd 2:c4d4f0f9d77c 34 in.mode(PullUp);
strysd 6:7f90a61e1a69 35 in.rise(&flip);
strysd 1:e2034bcdb101 36
strysd 3:bf0a5effbed2 37 printf("\rStarting measure\n");
strysd 5:9be3080ca8ba 38
Neel 0:c5bcf643a8b1 39 while (1) {
strysd 1:e2034bcdb101 40 //Use interrupt
strysd 4:64d9c0bed75b 41 my_interval = 0;
strysd 1:e2034bcdb101 42 t1.start();
strysd 4:64d9c0bed75b 43 rest_in = IN_TIMES;
strysd 4:64d9c0bed75b 44 run555 = led = 1;
strysd 4:64d9c0bed75b 45 wait_ms(WAIT_IN);
strysd 6:7f90a61e1a69 46 run555 = led = 0;//force stop
strysd 3:bf0a5effbed2 47
strysd 4:64d9c0bed75b 48 if (my_interval < MIN_INTERVAL || my_interval > MAX_INTERVAL){
strysd 3:bf0a5effbed2 49 printf("\r not ready\n");
strysd 1:e2034bcdb101 50 } else {
strysd 4:64d9c0bed75b 51 my_freq = ONESEC_BY_MICRO / my_interval; // Convert to Hz
strysd 4:64d9c0bed75b 52 my_ohm = my_interval * CONV_KILO_OHM;// Convert to kilo ohm
strysd 6:7f90a61e1a69 53 printf("\r %.0f Hz, %.0f micro sec, %.1f kilo ohm \n",
strysd 6:7f90a61e1a69 54 my_freq, my_interval, my_ohm);
strysd 1:e2034bcdb101 55 }
strysd 3:bf0a5effbed2 56
strysd 4:64d9c0bed75b 57 wait_ms(WAIT_NEXT);
Neel 0:c5bcf643a8b1 58 }
Neel 0:c5bcf643a8b1 59 }