Bring unprecedented accuracy and versatility to voltage control with MCP4361 and ATmega328P
Ohm-inous possibilities
Published Feb 14, 2024
Click board™
DIGI POT 5 click
Dev. board
Arduino UNO Rev3
Compiler
NECTO Studio
MCU
ATmega328P
Replace cumbersome mechanical potentiometers with our digital alternative, improving reliability, durability, and allowing for advanced automation
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Hardware Overview
How does it work?
DIGI POT 5 Click is based on the MCP4361, an 8-bit quad digital potentiometer from Microchip. This is a very versatile quad-digital potentiometer controlled via the SPI interface. The device has four integrated digital potentiometer sections, which consist of a string of resistors - serially connected, with digitally controlled analog switches, used to connect the wiper terminal position. The wiper position value of 0x000h corresponds to the lower end of the resistor ladder, while 0x100h corresponds to the upper end. These values can be written in the volatile wiper registers, with one address for each of the four wipers. Each of the four wipers can be controlled in several ways. Writing data directly to the volatile wiper register will move the wiper to the specified location. Wiper value can also be incremented or decremented by writing data to the incrementing or decrementing registers, providing that the wiper is not locked and that the wiper register value is not 0x000h (prevents further decrease) or above 0x100h (prevents further increase). Increasing and decreasing commands will be disregarded if the wiper register is set to a value greater than 0x100h. The incrementing and decrementing registers allow for less overhead if the wiper position has to be increased or decreased, making it easy to interface with the
rotary encoder applications, for example. The MCP4361 also features the WiperLock™ function, which prevents further changes in the wiper position, effectively locking the wiper in place. The CS pin must be pulled beyond the predefined voltage level threshold (8.5V to 12.5V) to enable this functionality. When this happens, the device enters the high voltage communication mode (HV mode), and the WiperLock™ functions can be accessed. The click board has a dedicated high-voltage input pad (VIHH), which can drive the CS pin with the appropriate voltage level when the HV mode is required. The resistor ladder network can be completely turned off by writing to the terminal control registers. This effectively disconnects the potentiometer terminals from a circuit, reducing the power consumption of the MCP4361 and the electrical circuit the IC is used in. The terminal control registers can switch the wiper terminals and the two resistor terminals separately. A STATUS register is also used for storing various status-related information, such as the WiperLock™ status, EEPROM writes to protect the status, and so on. The EEPROM memory holds the wiper data, even after the power is down. Several (five) general purpose 9bit addresses and 4 NV wiper register addresses are copied to the wiper register addresses after the restart or
power-up, allowing the device to resume the wiper position from a previous, stored state. By default, the data registers are zeroed out, while the NV wiper registers hold the middle scale position for the wiper. DIGI POT 5 Click has one 2x10 pin standard, 2.54mm pitch header connecting the four potentiometer terminals. There are three SMD jumpers onboard: The SMD jumper labeled WP is used to set the WP pin state of the MCP4361. The WP pin is used as the hardware EEPROM write protection and a software WP bit of the STATUS register (writable in HV mode only). The hardware WP pin and the software WP bit must be set to disabled mode to write to EEPROM. The SMD jumper labeled PWR SEL selects the power supply voltage - 3.3V or 5V. This also affects the logic voltage levels used for the SPI communication. The SMD jumper labeled CS SEL selects the CS pin voltage level. If the HV mode is required, this jumper should be moved to the VIHH position so that the externally connected 8.5V to 12.5V power source can pull up the CS pin. If HV mode is not required, this SMD jumper should stay at the default position (CS). Note that while in the HV mode, the CS pin is used the same way as with the regular SPI communication, with a difference in logical levels - the HV mode logical HIGH is at least 8.5V.
Features overview
Development board
Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an
ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the
first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
32
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
2048
You complete me!
Accessories
Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
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 Arduino UNO Rev3 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 5 Click driver.
Key functions:
digipot5_generic_write- Generic Write functiondigipot5_generic_read- Generic Read functiondigipot5_increment_wiper- Increment Wiper function
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 DIGI POT 5 Click example
*
* # Description
* This example demonstrates the use of the DIGI POT 5 click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes all necessary peripherals and pins used for the DIGI POT 5 click.
* Also allows the device to be reset and configured to enable all wipers (4).
* UART console module will be initialized also in this function.
*
* ## Application Task
* Demonstrates the use of click driver functions by performing a control of
* the all wipers positions. By checking the uart console, user can be informed
* about the all current wipers positions.
*
* *note:*
* Increment/decrement command can be issued only to volatile wiper locations.
*
* \author Nemanja Medakovic
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "digipot5.h"
// ------------------------------------------------------------------ VARIABLES
static digipot5_t digipot5;
static log_t console;
static uint8_t i;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init( void )
{
digipot5_cfg_t digipot5_cfg;
log_cfg_t console_cfg;
// Click initialization.
digipot5_cfg_setup( &digipot5_cfg );
DIGIPOT5_MAP_MIKROBUS( digipot5_cfg, MIKROBUS_1 );
digipot5_init( &digipot5, &digipot5_cfg );
digipot5_reset( &digipot5 );
digipot5_default_cfg( &digipot5 );
/**
* 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( console_cfg );
log_init( &console, &console_cfg );
log_printf( &console, "*** DIGI POT 5 Initialization Done ***\r\n" );
log_printf( &console, "****************************************\r\n" );
}
void application_task( void )
{
log_printf( &console, "* Setting wiper 0 to zero scale.\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER0_VOL,
DIGIPOT5_RES_ZEROSCALE );
log_printf( &console, "* Setting wiper 1 to 3k Ohm.\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER1_VOL,
DIGIPOT5_RES_3KOHM );
log_printf( &console, "* Setting wiper 2 to half scale (5k Ohm).\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER2_VOL,
DIGIPOT5_RES_5KOHM_HALFSCALE );
log_printf( &console, "* Setting wiper 3 to full scale (10k Ohm).\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER3_VOL,
DIGIPOT5_RES_10KOHM_FULLSCALE );
Delay_ms( 3000 );
log_printf( &console, "* Decrementing wiper 3 by 5 steps.\r\n" );
for ( i = 0; i < 5; i++ )
{
digipot5_decrement_wiper( &digipot5, DIGIPOT5_REG_WIPER3_VOL );
}
Delay_ms( 3000 );
log_printf( &console, "* Incrementing wiper 0 by 10 steps.\r\n" );
for ( i = 0; i < 10; i++ )
{
digipot5_increment_wiper( &digipot5, DIGIPOT5_REG_WIPER0_VOL );
}
Delay_ms( 3000 );
log_printf( &console, "* Setting wiper 0 to 2k Ohm.\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER0_VOL,
DIGIPOT5_RES_2KOHM );
log_printf( &console, "* Setting wiper 1 to 2k Ohm.\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER1_VOL,
DIGIPOT5_RES_2KOHM );
log_printf( &console, "* Setting wiper 2 to 2k Ohm.\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER2_VOL,
DIGIPOT5_RES_2KOHM );
log_printf( &console, "* Setting wiper 3 to 2k Ohm.\r\n" );
digipot5_generic_write( &digipot5, DIGIPOT5_REG_WIPER3_VOL,
DIGIPOT5_RES_2KOHM );
Delay_ms( 3000 );
log_printf( &console, "****************************************\r\n" );
}
void main( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
Additional Support
Resources
Category:Digital potentiometer
