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9 years, 7 months ago.
how do i modify the code below to store data with respect to time, used for graph ploting.
- include "mbed.h"
- include "TextLCD.h"
- include "SDFileSystem.h"
SDFileSystem sd(p11, p12, p13, p9, "sd"); the pinout on the mbed Cool Components workshop board TextLCD lcd(p19, p20, p21, p22, p23, p24); rs, e, d4-d7 AnalogIn lightin(p18); defines Analog input for light at pin 18 float light; defines the light data as type float int main() { lcd.printf("light in lux!\n"); light = lightin; wait(0.5);
FILE *fp = fopen("/sd/mydir/sdtest.txt", "w"); if(fp == NULL) { error("Could not open file for write\n"); } else{ lcd.printf("SD card file successfully opened\n"); } fprintf(fp, "light:%2.1f", "time:%2.1f%%", light , time); fclose(fp);
}
Question relating to:
1 Answer
9 years, 7 months ago.
#include "mbed.h"
#include "TextLCD.h"
#include "AM2303.h"
TextLCD lcd(p19, p20, p21, p22, p23, p24);
AM2303 h(p18);
DigitalOut relay(p9);
int main()
{
int state;
/* Show splash screen */
lcd.cls();
lcd.locate(0, 0);
lcd.printf("AM2303 Humidity");
while(true) {
wait(2.0);
state = h.readData();
lcd.locate(0, 1); /
if (state != AM2303::OK) {
lcd.printf("<Error: %d>", state);
} else {
lcd.printf("T:%2.1fC, H:%2.1f%%", h.readTemperature(), h.readHumidity());
}
if ((h.readTemperature() < 10) && ( h.readHumidity() < 30) { // If tem <10c & humity <30%
relay= 0;
} else {
relay = 1;
}
}
}
It might be better to do it inside the if statement checking the state.
if (state != AM2303::OK) {
lcd.printf("<Error: %d>", state);
} else {
lcd.printf("T:%2.1fC, H:%2.1f%%", h.readTemperature(), h.readHumidity());
if ((h.readTemperature() < 10) && ( h.readHumidity() < 30)) { // If tem <10c & humity <30%
relay= 0;
} else {
relay = 1;
}
}
Good point.
It would also be a good idea to have a little smoothing and/or hysteresis in there so that the relay isn't thrashing around constantly when you are right on the transition point.
posted by 05 Aug 2015Many thanks Stephen your idea was very helpful And Andy will be greatful if you can give my an idea how to go about.
posted by 05 Aug 2015How to add hysteresis? There are lots of different ways to structure it but is mainly comes down to moving the thresholds.
// default thresholds to turn the relay on.
float tempTheshold = 10;
float humidityThreshold = 30;
if (relay == 0) { // if the previous result was below the threshold then raise the thresholds by 10%
tempTheshold *= 1.1;
humidityThreshold *= 1.1;
}
if ((h.readTemperature() < tempTheshold) && ( h.readHumidity() < humidityThreshold)) {
relay= 0;
} else {
relay = 1;
}