Unlock a new level of flexibility in resistance setting with TPL0501 and PIC18F26K20
Control a voltage with digital signals
Published Nov 01, 2023
Click board™
DIGI POT 2 Click
Dev. board
EasyPIC v8
Compiler
NECTO Studio
MCU
PIC18F26K20
Enhance signal conditioning and gain control with our digital potentiometer, ensuring accurate and rapid adjustments in a digitally connected world
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Hardware Overview
How does it work?
DIGI POT 2 Click is based on the TPL0501, a 256-taps, single-channel, digital potentiometer with an SPI interface from Texas Instruments. The TPL0501 can be used as a three-terminal potentiometer or a two-terminal rheostat. It has four screw terminals: A High terminal (H), a Low terminal (L), and two Wiper terminals (W), internally connected. The H and L terminals do not have polarity restrictions; H can be a higher voltage than L and vice-versa. The position of the wiper (W) terminal is controlled by the value in the 8-bit wiper resistance register. There are two functional
modes for the DIGI POT 2 Click. When all three terminals are used, the TPL0501 generates a voltage divider, where the voltage divider at wiper-to-H and wiper-to-L is proportional to the input voltage at H to L. It operates in rheostat mode as a variable resistor when only two terminals are used. Depending on the polarity, the variable resistance can be anywhere between the H and L terminals. In this case, the nominal resistance between H and L terminals is 10KΩ, and the TPL0501 has 256 tap positions of the wiper. DIGI POT 2 Click communicates with the host MCU using the
3-wire SPI serial interface as a write-only. The SCK timing frequency maximum is 25MHz. 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
EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any
circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.
Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development 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
PIC
MCU Memory (KB)
64
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
3936
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 EasyPIC v8 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 2 Click driver.
Key functions:
digipot2_set_wiper_positions- The function sets 8-bit wiper positions datadigipot2_convert_output- The 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 DigiPot2 Click example
*
* # Description
* The demo application changes the resistance using DIGI POT 2 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 2 Click board.
* Increments the wiper position by 10 positions every 5 seconds.
*
* @author Stefan Ilic
*
*/
#include "board.h"
#include "log.h"
#include "digipot2.h"
static digipot2_t digipot2;
static log_t logger;
uint8_t wiper_pos;
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
digipot2_cfg_t digipot2_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.
digipot2_cfg_setup( &digipot2_cfg );
DIGIPOT2_MAP_MIKROBUS( digipot2_cfg, MIKROBUS_1 );
err_t init_flag = digipot2_init( &digipot2, &digipot2_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 2 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;
digipot2_set_wiper_positions( &digipot2, wiper_pos );
Delay_ms( 5000 );
}
}
void main ( void ) {
application_init( );
for ( ; ; ) {
application_task( );
}
}
// ------------------------------------------------------------------------ END
