Using Linear Interpolation

For concise equations, we’ll use the following notations:

• (ROOM_TEMP_VAL_INT, ROOM_TEMP_VAL_DEC) is denoted temp_R
• (HOT_TEMP_VAL_INT, HOT_TEMP_VAL_DEC) is denoted temp_H
• ROOM_ADC_VAL is denoted ADC_R, its conversion to Volt is denoted V_ADCR
• HOT_ADC_VAL is denoted ADC_H, its conversion to Volt is denoted V_ADCH
• ROOM_INT1V_VAL is denoted INT1V_R
• HOT_INT1V_VAL is denoted INT1V_H

Using the (temp_R, ADC_R) and (temp_H, ADC_H) points, using a linear interpolation we have the following equation:

Given a temperature sensor ADC conversion value ADC_m, we can infer a coarse value of the temperature temp_C as:

[Equation 1]

Note 1: in the previous expression, we’ve added the conversion of the ADC register value to be expressed in V

Note 2: this is a coarse value because we assume INT1V=1V for this ADC conversion.

Using the (temp_R, INT1V_R) and (temp_H, INT1V_H) points, using a linear interpolation we have the following equation:

Then using the coarse temperature value, we can infer a closer to reality INT1V value during the ADC conversion as:

Back to [Equation 1], we replace INT1V=1V by INT1V = INT1V_m, we can then deduce a finer temperature value as:

[Equation 1bis]