Ensure stable and consistent voltage references with MCP1541 and STM32F031K6
Precision in a digital world
Published Oct 01, 2024
Click board™
DigiVref Click
Dev. board
Nucleo 32 with STM32F031K6 MCU
Compiler
NECTO Studio
MCU
STM32F031K6
From integrated circuits to sensor networks, our digital reference voltage solution empowers users to achieve voltage precision in the digital realm, setting a new benchmark for digital reference generation
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Hardware Overview
How does it work?
DigiVref Click is based on the MCP1541, a precise voltage reference IC by Microchip is used to provide an accurate voltage output. However, this IC is very prone to voltage drop when loaded, so even a small load of 2mA may cause a voltage drop at its output. Therefore, an operational amplifier with a unity gain is used as a buffer. The voltage reference output of 4.096V (VREF) is routed to a common pin of the CD74HC4051, an analog multiplexer/demultiplexer IC, by Texas Instruments. This circuit has a one-to-eight internal switch with a digitally selected position. The position of the switch can be selected by applying logic levels to pins S0 to S2. Four outputs of the CD74HC4051 are routed to a voltage divider circuit composed of four 10K resistors. By routing the VREF across the voltage divider, one of four output voltage reference values can be selected,
depending on the selected switch position. The output voltage (VOUT) can be set to one of the following values: 1.024V, 2.048V, 3.072V, and 4.096V. The CD74HC4051 is controlled by the SN74HC595, an 8-bit shift register IC with tri-state output registers, by Texas Instruments. The SN74HC595 allows the data to be shifted in and then latched at the output. The state of the output pins will not change, as long as there is no new data shifted in and latched to the parallel output register (or as long as the #OE pin stays LOW, but it is hardwired to the GND on this Click board™). This allows the Click board™ to be completely independent on the SPI interface, even if it is disconnected at some point. Once set, the selected reference voltage will be available at the VOUT connector (standard 1x2-pin header with 2.54mm pitch), as long as the Click board™ is
powered. There are two control pins available on the CD74HC4051 since there are only 4 valid positions. Control pin S2 is grounded, so the CD74HC4051 is controlled by means of two pins: S0 and S1. These pins are routed to Q1 and Q2 outputs of the SN74HC595 IC. The SN74HC595 IC is controlled over the SPI interface, with its pins routed to the respective mikroBUS™ pins (CS, MOSI, SCK). Note that SPI data values that set pins other than Q1 and Q2, will not have any effect on this Click board™. Besides the VOUT connector, the VOUT voltage is also routed to the AN pin of the mikroBUS™, allowing it to be used by the host MCU. Therefore, a note should be taken that the Click board™ is not intended to be used with 3.3V MCUs, especially if they do not have 5V tolerant pins. To use the Click board™ with 3.3V MCUs, a proper level shifting circuit must be used.
Features overview
Development board
Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The
board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,
and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M0
MCU Memory (KB)
32
Silicon Vendor
STMicroelectronics
Pin count
32
RAM (Bytes)
4096
You complete me!
Accessories
Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.
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 Nucleo 32 with STM32F031K6 MCU 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 DigiVref Click driver.
Key functions:
digivref_set_output_voltage- This function sets reference output voltage
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
* \brief DigiVref Click example
*
* # Description
* This app changes the reference output voltage.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization device.
*
* ## Application Task
* Changes the reference output voltage every 3 seconds.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "digivref.h"
// ------------------------------------------------------------------ VARIABLES
static digivref_t digivref;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
digivref_cfg_t cfg;
/**
* 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.
digivref_cfg_setup( &cfg );
DIGIVREF_MAP_MIKROBUS( cfg, MIKROBUS_1 );
digivref_init( &digivref, &cfg );
}
void application_task ( void )
{
digivref_set_output_voltage( &digivref, DIGIVREF_REF_VOLTAGE_4096mV );
Delay_ms( 3000 );
digivref_set_output_voltage( &digivref, DIGIVREF_REF_VOLTAGE_3072mV );
Delay_ms( 3000 );
digivref_set_output_voltage( &digivref, DIGIVREF_REF_VOLTAGE_2048mV );
Delay_ms( 3000 );
digivref_set_output_voltage( &digivref, DIGIVREF_REF_VOLTAGE_1024mV );
Delay_ms( 3000 );
digivref_set_output_voltage( &digivref, DIGIVREF_REF_VOLTAGE_2048mV );
Delay_ms( 3000 );
digivref_set_output_voltage( &digivref, DIGIVREF_REF_VOLTAGE_3072mV );
Delay_ms( 3000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
