Satoru Yoshida
test interruptIn feature with 555 timer
Dependencies: ClockControl PowerControl mbed
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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。
なるべく配線が交差しないように部品配置してみた例
Diff: main.cpp
- Revision:
- 6:7f90a61e1a69
- Parent:
- 5:9be3080ca8ba
- Child:
- 7:42e7f18361c8
--- a/main.cpp Tue Jun 04 06:14:19 2013 +0000
+++ b/main.cpp Sun Aug 11 08:34:00 2013 +0000
@@ -1,14 +1,6 @@
+//see mbed.org/users/strysd/notebook/measure_humidity_with_hs15p_and_lmc555/
#include "mbed.h"
-
-//see mbed.org/users/strysd/notebook/measure_humidity_with_hs15p_and_lmc555/
-#define CONV_KILO_OHM 0.0072 //if use 0.1 micro F
-#define IN_TIMES 10 //interrupt times
-#define READ_TIMER 3 //rest times when reads timer
-#define WAIT_IN 1000 //wait interrupts in msec
-#define WAIT_NEXT 4000 //wait next measurement in msec
-#define MAX_INTERVAL 100000 // > 0.1 sec ( < 10 Hz) in microseconds
-#define MIN_INTERVAL 20 // < 20 micro sec ( > 50 kHz) in microseconds
-#define ONESEC_BY_MICRO 1000000// 1 sec in microseconds
+#include "main.h"
InterruptIn in(p8); //connect to the Discharge of 555
DigitalOut run555(p9);//connect to the Reset of 555
@@ -22,15 +14,14 @@
void flip(void)
{
- if(rest_in > 0){
- if(rest_in < READ_TIMER){
- my_interval = t1.read_us();// Get time since last interrupt
- }
- t1.reset();// Reset timer and wait for next interrupt
- rest_in--;
+ if(rest_in < READ_TIMER){
+ my_interval = t1.read_us();// Get time since last interrupt
}
- if(rest_in == 0){
+ t1.reset();// Reset timer and wait for next interrupt
+ rest_in--;
+
+ if(rest_in <= 0){
//No use interrupt
run555 = led = 0;
t1.stop();
@@ -41,7 +32,7 @@
run555 = led = 0;
// Set up the interrupt
in.mode(PullUp);
- in.fall(&flip);
+ in.rise(&flip);
printf("\rStarting measure\n");
@@ -52,14 +43,15 @@
rest_in = IN_TIMES;
run555 = led = 1;
wait_ms(WAIT_IN);
+ run555 = led = 0;//force stop
if (my_interval < MIN_INTERVAL || my_interval > MAX_INTERVAL){
printf("\r not ready\n");
} else {
my_freq = ONESEC_BY_MICRO / my_interval; // Convert to Hz
my_ohm = my_interval * CONV_KILO_OHM;// Convert to kilo ohm
- printf("\r %d Hz, %d micro sec, %4.1f kilo ohm \n",
- (int)my_freq, (int)my_interval, my_ohm);
+ printf("\r %.0f Hz, %.0f micro sec, %.1f kilo ohm \n",
+ my_freq, my_interval, my_ohm);
}
wait_ms(WAIT_NEXT);