Intermediate
30 min

Master the art of precise timing with CS2200-CP and ATmega328P

Clock frequency synthesizer

Clock Gen 4 Click with Arduino UNO Rev3

Published Feb 14, 2024

Click board™

Clock Gen 4 Click

Dev Board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328P

Integrate an advanced clock generator into your solution and witness the transformative impact on timing control

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Hardware Overview

How does it work?

Clock Gen 4 Click is based on the CS2200-CP, an analog PLL architecture comprised of a Delta-Sigma fractional-N frequency synthesizer from Cirrus Logic. The Delta-Sigma fractional-N frequency synthesizer has a high resolution for Input/Output clock ratios, low phase noise, a wide range of output frequencies, and the ability to tune to a new frequency quickly. This synthesizer multiplies the timing reference clock by the value of N to generate a stable and low-jitter PLL clock on the connector labeled PLL Clock. This Click board™ also has another connector marked as AUX Clock that outputs a buffered version of one of the input/output clocks or a status signal, depending on register configuration. The analog PLL-based frequency synthesizer uses a low-jitter timing reference clock

as a time and phase reference for the internal voltage-controlled oscillator (VCO). The phase comparator compares the fractional-N divided clock with the original timing reference and generates a control signal filtered by the internal loop filter to generate the VCO’s control voltage that sets its output frequency. The Delta-Sigma modulator modulates the loop integer divide ratio to get the desired fractional ratio between the reference clock and the VCO output. This allows fast lock times for various output frequencies without external filter components. Clock Gen 4 Click provides the possibility of using both I2C and SPI interfaces with a maximum frequency of 100kHz for I2C and 6MHz for SPI communication. The selection can be performed by positioning SMD jumpers labeled

COMM SEL to an appropriate position. Note that all the jumpers must be placed on the same side, or the Click board™ may become unresponsive. While the I2C interface is selected, the CS2200-CP allows the choice of the least significant bit (LSB) of its I2C slave address. This can be done by using the SMD jumper labeled as ADDR SEL. This Click board™ can only be operated with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

clock-gen-4-click-hardware-overview

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.

Arduino UNO Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

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.

Click Shield for Arduino UNO accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
PB2
CS
SPI Clock
PB5
SCK
SPI Data OUT
PB4
MISO
SPI Data IN
PB3
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PC5
SCL
I2C Data
PC4
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Clock Gen 4 Click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Click Shield for Arduino UNO front image hardware assembly
Arduino UNO Rev3 front image hardware assembly
Charger 27 Click front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Arduino UNO Rev3 Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Arduino UNO MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output via Debug Mode

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for Clock Gen 4 Click driver.

Key functions:

  • void clockgen4_dev_ctl ( uint8_t dev_ctl ); - Function is used to write to Device Control register in order to apply settings.
  • void clockgen4_dev_cfg ( uint8_t dev_cfg ); - Function is used to write to Device Configuration 1 register in order to apply settings.
  • uint32_t clockgen4_set_ratio ( float ratio ); - Function is used to set the ratio between the output signal and the input clock.

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 main.c
 * @brief ClockGen4 Click example
 *
 * # Description
 * This example demonstrates the use of Clock Gen 4 click which is based on CS2200-CP for changing the channel clock. The CS2200-CP is an extremely 
 * versatile system clocking device that utilizes a programmable phase lock loop. The CS2200-CP is based on an analog PLL architecture and this 
 * architecture allows for frequency synthesis and clock generation from a stable reference clock. The CS2200-CP supports both I²C and SPI for full software control.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes I2C and SPI, sets CS pin as output and starts to write log, applies default settings and adjusted ratio to obtain a frequency.
 *
 * ## Application Task
 * Clock Gen 4 click is used in this example to generate and change the clock on the output channel.
 *
 * @author Jelena Milosavljevic
 *
 */

#include "board.h"
#include "log.h"
#include "clockgen4.h"

static clockgen4_t clockgen4;
static log_t logger;

uint8_t com_itfc = 0;

void application_init ( void ){
    log_cfg_t log_cfg;                     /**< Logger config object. */
    clockgen4_cfg_t clockgen4_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 " );
    
    Delay_ms ( 100 );
    log_printf( &logger, "---------------------" );
    log_printf( &logger, "  Clock Gen 4 Click  " );
    log_printf( &logger, "---------------------" );
    
    // Click initialization.
    clockgen4_cfg_setup( &clockgen4_cfg );
    CLOCKGEN4_MAP_MIKROBUS( clockgen4_cfg, MIKROBUS_1 );
    err_t init_flag  = clockgen4_init( &clockgen4, &clockgen4_cfg );
    if ( ( I2C_MASTER_ERROR == init_flag ) || ( SPI_MASTER_ERROR == init_flag ) ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    clockgen4_default_cfg ( &clockgen4 );
    log_info( &logger, " Application Task " );
    Delay_ms ( 100 );
}

void application_task ( void ){
    clockgen4_dev_ctl ( &clockgen4, CLOCKGEN4_AUX_OUT_DIS | CLOCKGEN4_CLK_OUT_EN );
    log_printf( &logger, "  PLL Clock          \r\n" );
    log_printf( &logger, "  output enabled!    \r\n" );
    log_printf( &logger, "---------------------\r\n" );
    Delay_ms ( 1000 );
    
    clockgen4_dev_ctl ( &clockgen4, CLOCKGEN4_AUX_OUT_EN | CLOCKGEN4_CLK_OUT_DIS );
    log_printf( &logger, "  AUX Clock          \r\n" );
    log_printf( &logger, "  output enabled!    \r\n" );
    log_printf( &logger, "---------------------\r\n" );
    Delay_ms ( 1000 );
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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