Create digitally controlled oscillator with LTC6903 and STM32F410RB
Timing perfection at your fingertips
Published Oct 08, 2024
Click board™
Clock Gen 5 Click
Dev. board
Nucleo 64 with STM32F410RB MCU
Compiler
NECTO Studio
MCU
STM32F410RB
Elevate performance and maximize efficiency by adding a clock generator to your solution
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Hardware Overview
How does it work?
Clock Gen 5 Click is based on the LTC6903, a low-power self-contained digital frequency source providing a precision frequency from 1kHz to 68MHz set through a 3-wire digital interface from Analog Devices. The LTC6903 contains an internal feedback loop that controls a high-frequency square wave (VCO) operating between 34MHz and 68MHz. It is also a resistor-controlled oscillator that offers an integrated serial resistor DAC and a set of digital frequency dividers. The oscillator frequency is inversely proportional to the resistance of the DAC, where step size ranges between 0.05% and 0.1% of the frequency. In most frequency ranges, the output of the Clock Gen 5 Click is generated as a division of the higher internal clock
frequency. This helps to minimize jitter and sub-harmonics at the output of the device. In the highest frequency ranges, the division ratio is reduced, which will result in greater cycle-to-cycle jitter as well as spurs at the internal sampling frequency. The output clock signals, available on the SMA connectors with an impedance of 50Ω labeled as MAIN and AUX CLOCK, are primarily conducted through the TC7SZ125FU, a 3-state bus buffer before outputting allowing the LTC6903 to operate normally, producing the required output. Clock Gen 5 Click communicates with MCU using the 3-Wire SPI serial interface and operates at a clock frequency of up to 20 MHz. The output signals are controlled by the register bits MODE1 and MODE0,
where the outputs can be disabled through these bits. When both output signals are disabled through the mode control bits, the internal oscillator is also disabled. The OE pin routed on the RST pin of the mikroBUS™ socket can also be used to asynchronously disable either output without shutting down the oscillator entirely. 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. However, the 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
Nucleo-64 with STM32F410RB MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
128
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
32768
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 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 STM32 Nucleo-64 board with our Click Shield for Nucleo-64, 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 Nucleo 64 with STM32F410RB 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 Clock Gen 5 Click driver.
Key functions:
void clockgen5_out_enable ( uint8_t en_out )- Enable output function.void clockgen5_set_config ( uint8_t cfg )- Set configuration function.void clockgen5_set_freq ( float freq )- Set frequency 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 ClockGen5 Click example
*
* # Description
* This is an example that demonstrates the use of the Clock Gen 5 click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization driver enables - SPI,
* set output configuration CLK 180, also write log.
*
* ## Application Task
* In this example, we adjusts different frequencies every 3 sec.
* Results are being sent to the Uart Terminal where you can track their changes.
*
*
* @author Stefan Ilic
*
*/
#include "board.h"
#include "log.h"
#include "clockgen5.h"
static clockgen5_t clockgen5;
static log_t logger;
void application_init ( void ) {
log_cfg_t log_cfg; /**< Logger config object. */
clockgen5_cfg_t clockgen5_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.
clockgen5_cfg_setup( &clockgen5_cfg );
CLOCKGEN5_MAP_MIKROBUS( clockgen5_cfg, MIKROBUS_1 );
err_t init_flag = clockgen5_init( &clockgen5, &clockgen5_cfg );
if ( SPI_MASTER_ERROR == init_flag ) {
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... %d", init_flag );
for ( ; ; );
}
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " Enabling Output \r\n" );
clockgen5_out_enable( &clockgen5, CLOCKGEN5_OUTPUT_ENABLE);
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " Set configuration \r\n" );
log_printf( &logger, "-----------------------\r\n" );
clockgen5_set_config( &clockgen5, CLOCKGEN5_CFG_ON_CLK_180 );
Delay_ms( 500 );
log_info( &logger, " Application Task " );
}
void application_task ( void ) {
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " 12.0 MHz \r\n" );
clockgen5_set_freq( &clockgen5, 12000.0 );
Delay_ms( 3000 );
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " 8.0 MHz \r\n" );
clockgen5_set_freq( &clockgen5, 8000.0 );
Delay_ms( 3000 );
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " 5.5 MHz \r\n" );
clockgen5_set_freq( &clockgen5, 5500.0 );
Delay_ms( 3000 );
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " 2.7 MHz \r\n" );
clockgen5_set_freq( &clockgen5, 2700.0 );
Delay_ms( 3000 );
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " 0.8 MHz \r\n" );
clockgen5_set_freq( &clockgen5, 800.0 );
Delay_ms( 3000 );
log_printf( &logger, "-----------------------\r\n" );
log_printf( &logger, " 0.2 MHz \r\n" );
clockgen5_set_freq( &clockgen5, 200.0 );
Delay_ms( 3000 );
}
void main ( void ) {
application_init( );
for ( ; ; ) {
application_task( );
}
}
// ------------------------------------------------------------------------ END
