This version (05 Feb 2014 19:02) was approved by Lars-Peter Clausen.The Previously approved version (01 Oct 2012 15:27) is available.
Table of Contents
Supported Devices
Evaluation Boards
Overview
The ADT7420 is a high accuracy digital temperature sensor offering breakthrough performance over a wide industrial range, housed in an LFCSP package. It contains a band gap temperature reference and a 13-bit ADC to monitor and digitize the temperature to a 0.0625°C resolution. The ADC resolution, by default, is set to 13 bits (0.0625°C). This can be changed to 16 bits (0.0078°C) by setting Bit 7 in the configuration register to 1 (Register Address 0x03). The ADT7420 is guaranteed to operate over supply voltages from 2.7 V to 5.5 V. Operating at 3.3 V, the average supply current is typically 210 μA. The ADT7420 has a shutdown mode that powers down the device and offers a shutdown current of typically 2 μA. The ADT7420 is rated for operation over the −40°C to +150°C temperature range.
Pin A0 and Pin A1 are available for address selection, giving the ADT7420 four possible I2C addresses. The CT pin is an open-drain output that becomes active when the temperature exceeds a programmable critical temperature limit. The default critical temperature limit is 147°C. The INT pin is also an open-drain output that becomes active when the temperature exceeds a programmable limit. The INT and CT pins can operate in either comparator or interrupt mode.
Applications
- RTD and thermistor replacement
- Medical equipment
- Cold junction compensation
- Industrial control and test
- Food transportation and storage
- Environmental monitoring and HVAC
The goal of this project (Microcontroller No-OS) is to be able to provide reference projects for lower end processors, which can't run Linux, or aren't running a specific operating system, to help those customers using microcontrollers with ADI parts. Here you can find a generic driver which can be used as a base for any microcontroller platform and also specific drivers for different microcontroller platforms.
Driver Description
The driver contains two parts:
- The driver for the ADT7420 part, which may be used, without modifications, with any microcontroller.
- The Communication Driver, where the specific communication functions for the desired type of processor and communication protocol have to be implemented. This driver implements the communication with the device and hides the actual details of the communication protocol to the ADI driver.
The Communication Driver has a standard interface, so the ADT7420 driver can be used exactly as it is provided.
There are three functions which are called by the ADT7420 driver:
- I2C_Init() – initializes the communication peripheral.
- I2C_Write() – writes data to the device.
- I2C_Read() – reads data from the device.
I2C driver architecture
The implementation of these three functions depends on the used microcontroller.
The following functions are implemented in this version of ADT7420 driver:
| Function | Description |
|---|---|
| unsigned char ADT7420_GetRegisterValue(unsigned char registerAddress) | Reads the value of a register. |
| void ADT7420_SetRegisterValue(unsigned char registerAddress, unsigned char registerValue) | Sets the value of a register. |
| char ADT7420_Init(void) | Initializes the comm. peripheral and checks if the device is present. |
| void ADT7420_Reset(void) | Resets the ADT7420. |
| void ADT7420_SetOperationMode(unsigned char mode) | Sets the operational mode for ADT7420. |
| void ADT7420_SetResolution(unsigned char resolution) | Sets the resolution for ADT7420. |
| float ADT7420_GetTemperature(void) | Reads the temperature data and converts it to Celsius degrees. |
resources/tools-software/uc-drivers/adt7420.txt · Last modified: 28 Jun 2013 10:10 by Lucian Sin