Grove (Seeed Studio) temp sensor 101020015 compatibility issue

[EdtheWino]

Evidently the ADC module w/ the ESP32 does not properly extrapolate the conversion algorithm
offered by Seeed. The analog value displayed is always: -273.15; the last parameter used in the 1st line of the algorithm.
Is there a workaround for this issue?

Code: [Select all] [Expand/Collapse]

1.   #include <math.h>
2.  
3.   #define ONBOARD_LED  2  
4.  
5.  
6.     const int switchPin = 4;    // Board Digital Input GPIO4
7.     int switchState = 0;
8.  
9.     const int B = 4275;               // B value of the thermistor;  +- 275 = .6 C (1.0 F)
10.     const uint32_t R0 = 100000;            // R0 = 100k; int type uint32_t required (unsigned 32 bit)
11.     const int tmp_adj_1 = 4;                      // sensor 1 calibration adjustment
12.      
13.     float space_temp_1;                      //    Grove - Temperature Sensor connect to (GPIO) input pin
14.     float sp_temp_1;
15.     float sp_temp_1F;
16.     float Low_Tmp_Alm = 38.00;      // Low Alarm Setpoint  
17.  
18. void loop()
19. {
20.   digitalWrite(ONBOARD_LED,HIGH);            //  Blink for run indicator
21.      delay(200);
22.      digitalWrite(ONBOARD_LED, LOW);
23.      
24.      switchState = digitalRead(switchPin);       //Pressure Input Pin Read
25.      space_temp_1 = analogRead(39);            // Space Temp Input Read
26.      
27.      delay(500);
28.                  //  ***************** Low Alarm Function ***************
29.  
30.       float R1 = 1023.0 / space_temp_1 - 1.0;
31.       R1 = R0 * R1;
32.            
33.       float sp_temp_1 = 1.0 / (log(R1 / R0) / B + 1 / 298.15) - 273.15;   //  convert to temperature via datasheet
34.       float sp_temp_1F = (sp_temp_1 * 9 / 5) + 32 - tmp_adj_1;            // convert C to F    
35.      
36.                                      
37.       Serial.println("........");
38.       Serial.println("                  Space Temp =     ");
39.       Serial.print(sp_temp_1);
40.       Serial.println();
41.       Serial.println("........");
42.  //     Serial.println("                 Pressure Alarm input =     ");
43.  //     Serial.print(switchState);
44.       Serial.println();
45.  
46.  
47. }

GeSHi © Codebox Plus Extension

[lbernstone]

I'm actually surprised you aren't getting division by zero errors.
You need to set the pinMode in your setup (or at the top of your loop).

Code: Select all

pinMode(39, INPUT);

[EdtheWino]

deleted

[EdtheWino]

I'm actually surprised you aren't getting division by zero errors.
You need to set the pinMode in your setup (or at the top of your loop).

Code: Select all

pinMode(39, INPUT);

Ibernstone,

I inadvertently failed to copy the void setup() into the original post. The pinMode is defined there.