What is Mcp45xx

MCP45XX is a C library designed for the 7/8-Bit Single/Dual I2C Digital Potentiometer (POT) with Nonvolatile Memory, specifically for the MCP454X/456X/464X/466X series from Microchip. It allows for precise control of resistance in electronic circuits.

Use cases

Use cases for MCP45XX include volume control in audio devices, tuning circuits in RF applications, and dynamic adjustment of sensor gain in measurement systems.

How to use

To use MCP45XX, integrate the library into your C/C++ project by implementing the necessary interfacing functions for your platform. The library supports various microcontrollers with I2C capabilities, such as STM32, ESP32, and NXP.

Key features

Key features include single or dual resistor network options, 7-bit and 8-bit resolution, multiple resistance values (5kΩ to 100kΩ), nonvolatile memory for wiper settings, I2C interface with high-speed support, and low power consumption.

Where to use

MCP45XX can be used in various applications including audio equipment, sensor calibration, adjustable power supplies, and any electronic device requiring precise resistance control.

MCP4562 library

This readme explains some of the functionalities of the 7/8-Bit Single/Dual I2C Digital POT with Nonvolatile Memory library from Microchip and how to use it. This digital potentiometer has the following characteristics:

• Single or Dual Resistor Network Options
• Potentiometer or Rheostat Configuration Options
• Resistor Network Resolution
  • 7-bit: 128 Resistors (129 Steps)
  • 8-bit: 256 Resistors (257 Steps)
• RAB Resistances Options of:
  • 5kOhm
  • 10 kOhm
  • 50 kOhm
  • 100 kOhm
• Zero-Scale to Full-Scale Wiper Operation
• Low Wiper Resistance: 75 (typical)
• Low Tempco:
  • Absolute (Rheostat): 50 ppm typical
    (0°C to 70°C)
  • Ratiometric (Potentiometer): 15 ppm typical
• Nonvolatile Memory
  • Automatic Recall of Saved Wiper Setting
  • WiperLock™ Technology
  • 10 General Purpose Memory Locations
• I2C Serial Interface
  • 100 kHz, 400 kHz and 3.4 MHz Support
• Serial Protocol Allows:
  • High-Speed Read/Write to Wiper
  • Read/Write to EEPROM
  • Write Protect to be Enabled/Disabled
  • WiperLock to be Enabled/Disabled
• Resistor Network Terminal Disconnect Feature
  via the Terminal Control (TCON) Register
• Write Protect Feature:
  • Hardware Write Protect (WP) Control Pin
  • Software Write Protect (WP) Configuration Bit
• Brown-out Reset Protection (1.5V typical)
• Serial Interface Inactive Current (2.5 uA typical)
• High-Voltage Tolerant Digital Inputs: Up to 12.5V
• Wide Operating Voltage:
  • 2.7V to 5.5V - Device Characteristics Specified
  • 1.8V to 5.5V - Device Operation
• Wide Bandwidth (-3dB) Operation:
  • 2 MHz (typ.) for 5.0 k Device
• Extended Temperature Range (-40°C to +125°C)

Implementation methodology

This library is implemented in C and is platform independent. It means that we can easily add it to any project for any platform that has an I2C port and uses C/C++ language by implementing only the interfacing functions. Examples: STM32, ESP32, NXP, etc.

Implementation is done in a manner to bring high level functions to user in order to make it easy to use and abstract him of all hardware specificities. Also, implementation is robust with error handling and data validation.

The best way to understand the program is to read function headers. The file mcp4562.h contains all enumeration,structure and function prototypes with understandable names and functions headers are in the file mcp4562.c.

How to use

To use the library, just add the files:

• mcp4562.c
• mcp4562.h
• mcp4562_defines.h

to your project and include the file mcp4562.h in your main file.

Then, declare a variable of type MCP4562_HandleTypeDef and init it with the function MCP4562_ErrorType MCP4562_Init(MCP4562_HandleTypeDef *mcp4562, uint8_t i2c_address_offset);. For that you must give the address_offset with the I2C address you set on your hardware. Caution, you must give the offset and not the address of the device.

You must then implement the following functions and add them to the handle:

• MCP4562_ErrorType (*write)(uint8_t address, uint8_t *data, uint8_t bytes_to_send);
• MCP4562_ErrorType (*read)(uint8_t address, uint8_t *data, uint8_t bytes_to_read);
• MCP4562_ErrorType (*delay)(uint32_t ms);
• MCP4562_ErrorType (*software_reset)(); // Facultative, only necessary if you want to implement the software reset

// Example:

MCP4562_ErrorType platform_write(uint8_t address, uint8_t *data, uint8_t bytes_to_send){
    // Your platform dependent I2C implementation

}

// ...

void main(){

    MCP4562_HandleTypeDef myHandle;

    MCP4562_Init(&myHandle, 0);

    myHandle.write = platform_write;
    myHandle.read = //...
}

Those functions are the interface between the library and the hardware. Information about their implementation can be found in the file mcp4562.h.

Also, you must choose the model device and option you have in the file mcp4562_defines.h by commenting and uncommenting the one you have. This will allow you to use only the function that works for your device.

After that, you should be good to go and use the MCP4562 functions.

Actual state

Implementation that needs to be done:

• General call commands
• High voltage commands
• manage correctly the discrimination between different devices of the same family