Scott Vincent / temp_fan

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temp_fans.cpp@0:c8b4d53dbed4, 2021-03-15 (annotated)

Committer:
tsmith10
Date:
Mon Mar 15 21:29:34 2021 +0000
Revision:
0:c8b4d53dbed4
Child:
1:1faa8c2f5507
First draft

Who changed what in which revision?

UserRevisionLine numberNew contents of line
tsmith10 0:c8b4d53dbed4 1 #include "mbed.h"
tsmith10 0:c8b4d53dbed4 2 #include "temp_fans.h"
tsmith10 0:c8b4d53dbed4 3
tsmith10 0:c8b4d53dbed4 4
tsmith10 0:c8b4d53dbed4 5 temp_fans::temp_fans():LM35(A2),fan(A5){}
tsmith10 0:c8b4d53dbed4 6
tsmith10 0:c8b4d53dbed4 7 void temp_fans::temp_fans_UPDATE(void) {
tsmith10 0:c8b4d53dbed4 8
tsmith10 0:c8b4d53dbed4 9
tsmith10 0:c8b4d53dbed4 10 float temp, sum, duty_cycle;
tsmith10 0:c8b4d53dbed4 11 int i; //For loop counter
tsmith10 0:c8b4d53dbed4 12 fan.period_us(40.0f); // 40 micro second period (25KHz) for fan PWM
tsmith10 0:c8b4d53dbed4 13
tsmith10 0:c8b4d53dbed4 14
tsmith10 0:c8b4d53dbed4 15 sum=0; //Reset sum for average value of input readings
tsmith10 0:c8b4d53dbed4 16 for(i=0; i<10; i++) {
tsmith10 0:c8b4d53dbed4 17 sum=sum+LM35.read();
tsmith10 0:c8b4d53dbed4 18 wait_us(10000);
tsmith10 0:c8b4d53dbed4 19 }
tsmith10 0:c8b4d53dbed4 20
tsmith10 0:c8b4d53dbed4 21 temp=(sum/10*3.3)*100; //Average & factor for analog to temperature conversion
tsmith10 0:c8b4d53dbed4 22
tsmith10 0:c8b4d53dbed4 23 printf("Temperature: %d oC\r\n", (int)temp);
tsmith10 0:c8b4d53dbed4 24
tsmith10 0:c8b4d53dbed4 25 if (temp<15) {
tsmith10 0:c8b4d53dbed4 26 duty_cycle=0; //Fans not in motion
tsmith10 0:c8b4d53dbed4 27 }
tsmith10 0:c8b4d53dbed4 28 else if(temp>75) {
tsmith10 0:c8b4d53dbed4 29 printf("ERROR: SYSTEM OVERHEATED!\r\n");
tsmith10 0:c8b4d53dbed4 30 duty_cycle=100; //Fans at MAX speed
tsmith10 0:c8b4d53dbed4 31 }
tsmith10 0:c8b4d53dbed4 32 else {
tsmith10 0:c8b4d53dbed4 33 duty_cycle=(temp-15)*2/100; //Incrementing PWM value by 2% per degree from [15-75 oC]
tsmith10 0:c8b4d53dbed4 34 }
tsmith10 0:c8b4d53dbed4 35
tsmith10 0:c8b4d53dbed4 36 fan.write(duty_cycle); // Duty cycle (relative to period)
tsmith10 0:c8b4d53dbed4 37 printf("PWM Speed: %d%\r\n\r\n", (int)(duty_cycle*100));
tsmith10 0:c8b4d53dbed4 38
tsmith10 0:c8b4d53dbed4 39
tsmith10 0:c8b4d53dbed4 40 }
tsmith10 0:c8b4d53dbed4 41
tsmith10 0:c8b4d53dbed4 42
tsmith10 0:c8b4d53dbed4 43
tsmith10 0:c8b4d53dbed4 44