Control resistance using digital signals with MCP4161 and MK64FN1M0VDC12
8-bit single SPI digital potentiometer with non-volatile memory
Published Aug 21, 2023
Click board™
DIGI POT Click
Dev. board
Clicker 2 for Kinetis
Compiler
NECTO Studio
MCU
MK64FN1M0VDC12
Achieve digital control of electrical parameters through this cutting-edge digital potentiometer solution, simplifying system tuning and optimization
A
A
Hardware Overview
How does it work?
DIGI POT Click is based on the MCP4161, an 8-bit single SPI digital POT with non-volatile memory from Microchip. The MCP4161 has a resistance of 10kΩ and low wiper resistance, with a typical 75Ω. It can be used as a three-terminal potentiometer or a two-terminal rheostat while floating either of the terminals (A or B). DIGI POT Click has four screw terminals: PA and PB as analog terminals A and B of the MCP4161, a PW as a wiper terminal of the digital potentiometer, and one for ground. The PA and PB terminals do not have polarity restrictions; PA can be a higher voltage than PB and vice-versa.
The position of the wiper (PB) terminal is controlled by the value in the 8-bit wiper resistance register. There are two functional modes of this Click board™. When all three terminals are used, the MCP4161 generates a voltage divider, where the voltage divider at wiper-to-PA and wiper-to-PB is proportional to the input voltage at PA to PB. It operates in rheostat mode as a variable resistor when only two terminals are used. DIGI POT Click communicates with the host MCU using the 3-Wire SPI serial interface as a write-only. The SCK timing frequency maximum is 10MHz. It features a
WiperLock™ Technology for automatically recalling saved wiper settings from EEPROM. In addition to the SMD MCP4161, this Click board™ features 6 PTHs for the DIP variant of this chip. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.
Features overview
Development board
Clicker 2 for Kinetis is a compact starter development board that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit ARM Cortex-M4F microcontroller, the MK64FN1M0VDC12 from NXP Semiconductors, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a JTAG programmer connector, and two 26-pin headers for interfacing with external electronics. Its compact design with clear and easily recognizable silkscreen markings allows you to build gadgets with unique functionalities and
features quickly. Each part of the Clicker 2 for Kinetis development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the Clicker 2 for Kinetis programming method, using a USB HID mikroBootloader or an external mikroProg connector for Kinetis programmer, the Clicker 2 board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Micro-B cable, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or
using a Li-Polymer battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several user-configurable buttons and LED indicators. Clicker 2 for Kinetis is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
1024
Silicon Vendor
NXP
Pin count
121
RAM (Bytes)
262144
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Clicker 2 for Kinetis as your development board.
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
Software Support
Library Description
This library contains API for DIGI POT Click driver.
Key functions:
digipot_set_wiper_positions- This function sets 8-bit wiper positions datadigipot_convert_output- This function convert 10-bit ADC value to volatage reference
Open Source
Code example
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* @file main.c
* @brief DigiPot Click example
*
* # Description
* The demo application changes the resistance using DIGIPOT Click.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes SPI and LOG modules.
*
* ## Application Task
* This is an example which demonstrates the use of DIGI POT Click board.
* Increments the wiper position by 10 positions every 5 seconds.
*
* @author Stefan Ilic
*
*/
#include "board.h"
#include "log.h"
#include "digipot.h"
static digipot_t digipot;
static log_t logger;
uint8_t wiper_pos;
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
digipot_cfg_t digipot_cfg; /**< Click config object. */
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, " Application Init " );
// Click initialization.
digipot_cfg_setup( &digipot_cfg );
DIGIPOT_MAP_MIKROBUS( digipot_cfg, MIKROBUS_1 );
err_t init_flag = digipot_init( &digipot, &digipot_cfg );
if ( SPI_MASTER_ERROR == init_flag ) {
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
log_printf( &logger, "----------------\r\n" );
log_printf( &logger, " DIGI POT Click\r\n" );
log_printf( &logger, "----------------\r\n" );
}
void application_task ( void ) {
for ( uint16_t n_cnt = 127; n_cnt < 255; n_cnt += 10 ) {
wiper_pos = ( uint8_t ) n_cnt;
digipot_set_wiper_positions( &digipot, wiper_pos );
Delay_ms( 5000 );
}
}
void main ( void ) {
application_init( );
for ( ; ; ) {
application_task( );
}
}
// ------------------------------------------------------------------------ END
