Experience ultra-responsive pulse generation with LTC6993-2 and STM32F407VGT6
“One-shot” pulse generator
Published Dec 29, 2023
Click board™
One Shot Click
Dev Board
Clicker 4 for STM32F4
Compiler
NECTO Studio
MCU
STM32F407VGT6
Create accurately timed pulses, and ensure synchronized operations in various systems and devices
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Hardware Overview
How does it work?
One Shot Click is based on the LTC6993-2, a monostable multivibrator (also known as a "one-shot" pulse generator) with a programmable pulse width of 1μs to 33.6 seconds from Analog Devices. The LTC6993-2 is part of the TimerBlox® family of versatile silicon timing devices. A single resistor, RSET, programs an internal master oscillator frequency, setting the LTC6993's time base. The output pulse width is determined by this master oscillator and an internal clock divider, NDIV, programmable to eight settings from 1 to 221. The output pulse is initiated by a transition on the trigger input (TRIG). Each part can be configured to generate positive or negative output pulses. The LTC6993-2 has four versions to provide different trigger signal polarity and retrigger capability. Besides that, LTC6993-2 also offers the ability to dynamically adjust the width of the output pulse via a separate control voltage brought to the SET
pin of the IC. A simple trimmer or potentiometer could be used; however, due to reliability reasons, the AD5241 digital potentiometer is used for that purpose on One Shot Click. The word is also about a 256-position digital potentiometer with a low-temperature coefficient (30 ppm/°C) from Analog Devices. The AD5241 communicates with the microcontroller over the standard I2C interface so that the user can easily control and precisely calculate the output pulse width just by simply setting the wiper value in the AD5241 registers. One Shot Click also contains the multi-turn trimmer wired as a resistor divider between V+ and GND and brought to the DIV pin of the LTC6993-2. The DIV pin is the programmable divider and polarity input. The polarity input, which pin voltage is internally converted into a 4-bit result (DIVCODE). The MSB of DIVCODE (POL) determines the polarity of the OUT pins. When
POL = 0, the output produces a positive pulse. When POL = 1, the output produces a negative pulse. That way, the user can easily set the output pulse width range, and polarity by setting the desired voltage on the trimmer mentioned (VR1). This Click also contains test points to ease the user's access to the referent voltage. One can separate the trimmer from the rest of the circuit using the separation switch (SW1), then precisely set and measure the desired voltage and turn the switch back in the ON position. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC 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 4 for STM32F4 is a compact development board designed as a complete solution that you can use to quickly build your own gadgets with unique functionalities. Featuring an STM32F407VGT6 MCU, four mikroBUS™ sockets for Click boards™ connectivity, power management, and more, it represents a perfect solution for the rapid development of many different types of applications. At its core is an STM32F407VGT6 MCU, a powerful microcontroller by STMicroelectronics based on the high-performance
Arm® Cortex®-M4 32-bit processor core operating at up to 168 MHz frequency. It provides sufficient processing power for the most demanding tasks, allowing Clicker 4 to adapt to any specific application requirements. Besides two 1x20 pin headers, four improved mikroBUS™ sockets represent the most distinctive connectivity feature, allowing access to a huge base of Click boards™, growing on a daily basis. Each section of Clicker 4 is clearly marked, offering an intuitive and clean interface. This makes working with the
development board much simpler and, thus, faster. The usability of Clicker 4 doesn’t end with its ability to accelerate the prototyping and application development stages: it is designed as a complete solution that can be implemented directly into any project, with no additional hardware modifications required. Four mounting holes [4.2mm/0.165”] at all four corners allow simple installation by using mounting screws.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
10
Silicon Vendor
STMicroelectronics
Pin count
100
RAM (Bytes)
100
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Clicker 4 for STM32F4 as your development board.
Track your results in real time
Application Output
After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.
After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.
Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.
Software Support
Library Description
This library contains API for One Shot Click driver.
Key functions:
oneshot_get_resistance- This function reads the resistance data from the AD5241 chiponeshot_digital_read_rst- This function reads the digital signal from the RST pinoneshot_digital_write_cs- This function writes the specified digital signal to the CS pin
Open Source
Code example
This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.
/*!
* \file
* \brief OneShot Click example
*
* # Description
* This example shows the user how to configure and use the One Shot click. The click has a
* monostable monovibrator which cam generate a pulse of width between 1μs and 33.6 seconds.
*
* The demo application is composed of two sections :
*
* ## Application Init
* This function initializes and configures the logger and click modules. Resistance data,
* acquired from the AD5241, is displayed at the end of the initialization process.
*
* ## Application Task
* This function triggers one shot every 8 seconds.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "oneshot.h"
// ------------------------------------------------------------------ VARIABLES
static oneshot_t oneshot;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( )
{
log_cfg_t log_cfg;
oneshot_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.
oneshot_cfg_setup( &cfg );
ONESHOT_MAP_MIKROBUS( cfg, MIKROBUS_1 );
oneshot_init( &oneshot, &cfg );
Delay_100ms( );
oneshot_default_cfg( &oneshot );
Delay_100ms( );
log_printf( &logger, " * Resistance: %.1f Ohm\r\n", oneshot_get_resistance( &oneshot ) );
}
void application_task ( )
{
oneshot_digital_write_cs( &oneshot, 1 );
Delay_ms( 1 );
oneshot_digital_write_cs( &oneshot, 0 );
log_printf( &logger, " * One shot triggered \r\n" );
log_printf( &logger, " --------------------------- \r\n" );
Delay_ms( 8000 );
}
void main ( )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
