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HardFOC driver

MCP9700 Driver

A C++17 driver for the Microchip MCP9700, MCP9700A and MCP9700B linear active thermistors. It reads the sensor's output voltage through your ADC and returns degrees Celsius, with the datasheet coefficients or your own calibration, on any MCU with an ADC input.

Quickstart API guide Source on GitHub

The driver has no platform code. You give it a small class that brings your ADC up and returns the voltage at the sensor's output pin; it does the rest: the transfer function, the coefficients and the error checks around each read.

Linear active thermistor (analog temperature sensor) MCP9700 / MCP9700A Microchip Technology
Function
Temperature to voltage: 500 mV at 0 °C, 10.0 mV/°C (typical)
Output
VOUT 100 mV to 1.75 V over the range; 100 µA maximum; drives capacitive loads
Supply
2.3 V to 5.5 V, 6 µA typical (12 µA maximum)
Accuracy (0 °C to +70 °C)
MCP9700 ±4 °C, MCP9700A ±2 °C maximum; MCP9700B ±1 °C from +20 °C to +70 °C
Range
−40 °C to +125 °C; to +150 °C for the high-temperature MCP9700 and MCP9700B (SOT-23, SC70)
Package
SOT-23-3, SC70-5, TO-92-3 (no TO-92 for the MCP9700B)
Driver mode
One ADC read per call, first-order transfer function with configurable coefficients

Datasheet (DS20001942L) · MCP9700 product page · MCP9700A product page

What you get

  • One object per sensor. Mcp9700Thermistor<YourAdc> takes your ADC adapter and a channel; several sensors share one ADC. See API guide.
  • Degrees Celsius from volts. ReadTemperatureCelsius() applies T = (V − 0.5 V) / 0.01 V/°C, the datasheet's first-order transfer function. See Transfer function.
  • Your calibration. Pass your own offset and slope to the constructor after a one-point or two-point calibration, or the MCP9701 coefficients. See Configuration.
  • Errors you can act on. Every call returns bool and LastError() says why; an open, grounded or shorted input fails instead of reading −50 °C. A failed read leaves your value untouched. See API guide.
  • Zero-overhead portability. The adapter is a template parameter with two methods: no virtual calls, no heap, no RTOS dependency. See Porting.
  • Tested without hardware. Host unit tests run the driver against a scripted ADC. See Testing and CI.

Where to go next

  • Quickstart

    Wire the sensor, write the adapter, print the temperature in about 15 lines.

  • Hardware

    Pins, output characteristics, ADC settings, accuracy and power.

  • Architecture

    The three layers and what each one owns.

  • API guide

    Initialise, read, calibrate and handle errors, task by task.

  • Porting

    Implement the ADC adapter for your MCU.

  • API reference

    Every class and member, generated from the headers.