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:
- 8:cb966096a916
- Parent:
- 7:42e7f18361c8
--- a/main.cpp Wed Nov 06 07:38:20 2013 +0000
+++ b/main.cpp Sun May 11 07:29:02 2014 +0000
@@ -1,62 +1,36 @@
-//see mbed.org/users/strysd/notebook/measure_humidity_with_hs15p_and_lmc555/
#include "mbed.h"
-#include "main.h"
+#include "PowerControl/EthernetPowerControl.h"
+#include "ClockControl/ClockControl.h"
-InterruptIn in(p8); //connect to the Discharge of 555
-DigitalOut run555(p9);//connect to the Reset of 555
+InterruptIn in(p8); //Connect from output of 555
DigitalOut led1(LED1);//running 555
-DigitalOut led2(LED2);//not ready
-Timer t1;
-float my_interval = 0;//between interrupts in microseconds
-float my_freq = 0;//Hz
-float my_ohm = 0;//ohm for HS15P
-int rest_in = 0;//rest of interrupt times
+/* stop USB Interface */
+#define USR_POWERDOWN (0x104)
+int semihost_powerdown() {
+ uint32_t arg;
+ return __semihost(USR_POWERDOWN, &arg);
+}
void flip(void)
{
- 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 <= 0){
- //No use interrupt
- run555 = led1 = 0;
- t1.stop();
- }
+ led1 = !led1;
}
int main() {
- run555 = led1 = led2 = 0;
- // Set up the interrupt
- in.mode(PullUp);
- in.rise(&flip);
+ led1 = 0;
- printf("\rStarting measure\n");
+ setSystemFrequency(0x3, 0x1, 6, 1);//clock down from 96MHz to 48MHz
+
+ semihost_powerdown();//Stop also USB Interface
+ PHY_PowerDown();//net
- while (1) {
- //Use interrupt
- my_interval = 0;
- t1.start();
- rest_in = IN_TIMES;
- run555 = led1 = 1;
- led2 = 0;
- wait_ms(WAIT_IN);
- run555 = led1 = 0;//force stop
-
- if (my_interval < MIN_INTERVAL || my_interval > MAX_INTERVAL){
- printf("\r not ready\n");
- led2 = 1;
- } else {
- my_freq = ONESEC_BY_MICRO / my_interval; // Convert to Hz
- my_ohm = my_interval * CONV_KILO_OHM;// Convert to kilo ohm
- printf("\r %.0f Hz, %.0f micro sec, %.1f kilo ohm \n",
- my_freq, my_interval, my_ohm);
- }
-
- wait_ms(WAIT_NEXT);
+ // Set up the interrupt
+ in.mode(PullNone);
+ in.rise(&flip);
+
+ while(1){
+ wait(1);
}
+
}
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