Split thermistor functions into separate logical units and add TODO

src/bus/i2c.c

@@ -14,11 +14,6 @@
 #define TW_MR_SLA_NACK 0x48  // SLA+R transmitted, NACK received
 #define TW_MR_DATA_ACK 0x50  // Data received, ACK returned
 
-// NTC conversion constants
-#define NTC01 1.009249522e-3
-#define NTC02 2.378405444e-4
-#define NTC03 2.019202697e-7
-
 // TODO: Error handling and recovery besides watchdog timer.
 // TODO: Add more documentation from the atmel data sheet.
 // TODO: ADS1115 continuous mode instead of single-shot?
@@ -477,7 +472,7 @@ static bool I2C_ADS1115_IsReady(void)
 	return reg & BIT(15);
 }
 
-word I2C_ADS1115_Read(int channel)
+word I2C_ADS1115_ReadRaw(int channel)
 {
 	word config;
 	word os, mode, rate, gain, mux;
@@ -563,21 +558,3 @@ word I2C_ADS1115_Read(int channel)
 
 	return I2C_ADS1115_ReadRegister(0x00);
 }
-
-float I2C_ADS1115_ReadThermistor(int channel)
-{
-	word raw;
-	float r1, t;
-	float logr2;
-
-	// TODO: Improve readability
-	// https://en.wikipedia.org/wiki/Steinhart%E2%80%93Hart_equation
-
-	raw = I2C_ADS1115_Read(channel);
-
-	r1 = (float) raw / 264.8f * 0.05f;
-	logr2 = log(10000.0f / (5.0f / r1 - 1.0f));
-	t = 1.0f / (NTC01 + NTC02 * logr2 + NTC03 * pow(logr2, 3));
-
-	return t - 273.15f; // Convert fahrenheit to celsius
-}

src/bus/i2c.h

@@ -28,7 +28,6 @@ int  I2C_AHT20_Init(void);
 int  I2C_AHT20_Read(float *temp, float *rhum);
 
 // ADS1115 analog to digital converter
-word   I2C_ADS1115_Read(int channel);
-float  I2C_ADS1115_ReadThermistor(int channel);
+word  I2C_ADS1115_ReadRaw(int channel);
 
 #endif // MAD_CORE_BUS_I2C_H