Generate high-frequency clock output with ICS501 and PIC32MZ2048EFM100

Phase-Locked Loop (PLL) mechanism

Published Jul 22, 2025

Click board™

PLL Click

Dev. board

Curiosity PIC32 MZ EF

Compiler

NECTO Studio

MCU

PIC32MZ2048EFM100

Generate highly stable and coherent high-frequency signals for applications requiring tight synchronization and minimal phase noise

Hardware Overview

How does it work?

PLL Click is based on the ICS501, a LOCO™ PLL clock multiplier, from Integrated Device Technology. This IC uses the Phase-Locked Loop to provide a high-frequency clock output, deriving input from a much cheaper, standard fundamental frequency crystal oscillator. Besides the onboard crystal oscillator fixed at 12MHz, it is possible to select the signal from the mikroBUS™ PWM pin as the clock input source. To select the desired multiplication factor, the states of the two input pins, S0 and S1, are routed to the mikroBUS™ pins RST and AN, respectively. These pins can be set to a HIGH or LOW logic state or disconnected (by tri-stating the MCU pins). The combination of these pins states will set the PLL

Click to a specific multiplier. The Output Enable (OE) pin of the ICS501 is used to turn off the output clock by setting it to a LOW logic level. It will additionally set the clock output pin in high impedance (Hi-Z) mode, allowing complete disconnection and no influence on the rest of the circuit, which is useful for experimenting and prototyping purposes. This pin is internally pulled to a HIGH logic level. The OE pin is routed to the CS pin of the mikroBUS™. PLL Click is equipped with two onboard SMD jumpers. The SMD jumper labeled as the VCC SEL is used to select the operating voltage level, consequently limiting the amplitude of the clock output signal with respect to the selected voltage. The other SMD jumper

labeled as the OSC SEL chooses the clock input source between the onboard 12MHz crystal oscillator or the external clock signal. The output signal is routed through the onboard SMA connector, which provides a secure connection and good signal shielding. PLL Click has a library containing functions for all the MIKROE compilers (mikroBASIC, mikroPASCAL, and mikroC). Although relatively easy to control, the library offers comprehensive functions that make the code readable and easy to use. The included example application demonstrates the use of these functions, and it can be used as a reference for custom projects.

Features overview

Development board

Curiosity PIC32 MZ EF development board is a fully integrated 32-bit development platform featuring the high-performance PIC32MZ EF Series (PIC32MZ2048EFM) that has a 2MB Flash, 512KB RAM, integrated FPU, Crypto accelerator, and excellent connectivity options. It includes an integrated programmer and debugger, requiring no additional hardware. Users can expand

functionality through MIKROE mikroBUS™ Click™ adapter boards, add Ethernet connectivity with the Microchip PHY daughter board, add WiFi connectivity capability using the Microchip expansions boards, and add audio input and output capability with Microchip audio daughter boards. These boards are fully integrated into PIC32’s powerful software framework, MPLAB Harmony,

which provides a flexible and modular interface to application development a rich set of inter-operable software stacks (TCP-IP, USB), and easy-to-use features. The Curiosity PIC32 MZ EF development board offers expansion capabilities making it an excellent choice for a rapid prototyping board in Connectivity, IOT, and general-purpose applications.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC32

MCU Memory (KB)

2048

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

524288

Used MCU Pins

mikroBUS™ mapper

Multiplier Adjustment

RPB4

Multiplier Adjustment

RA9

RST

Output Enable

RPD4

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

External Clock Source

RPE8

PWM

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

Curiosity PIC32MZ EF front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity PIC32 MZ EF as your development board.

GNSS2 Click front image hardware assembly

GNSS2 Click complete accessories setup image hardware assembly

Board mapper by product7 hardware assembly

Curiosity PIC32 MZ EF MCU Step hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

Software Support

Library Description

This library contains API for PLL Click driver.

Key functions:

pll_set_clock_output - This function settings clock output
pll_set_pll_4x - This function settings PLL x4
pll_set_pll_6x - This function settings PLL x6

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 PLL Click example
 * 
 * # Description
 * This app sets PLL signals.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes device.
 * 
 * ## Application Task  
 * Every 2 seconds, the PLL increases the input clock from min (x2) to max (x8) level.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "pll.h"

// ------------------------------------------------------------------ VARIABLES

static pll_t pll;
static log_t logger;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    pll_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.
    pll_cfg_setup( &cfg );
    PLL_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    pll_init( &pll, &cfg );
    pll_set_clock_output( &pll, PLL_CLOCK_ENABLE );
}

void application_task ( void )
{
    log_printf( &logger, " PLL level: x2\r\n\n" );
    pll_set_pll_2x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x3\r\n\n" );
    pll_set_pll_3x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x3.125\r\n\n" );
    pll_set_pll_3_125x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x4\r\n\n" );
    pll_set_pll_4x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x5\r\n\n" );
    pll_set_pll_5x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x5.3125\r\n\n" );
    pll_set_pll_5_3125x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x6\r\n\n" );
    pll_set_pll_6x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x6.25\r\n\n" );
    pll_set_pll_6_25x( &pll );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    log_printf( &logger, " PLL level: x8\r\n\n" );
    pll_set_pll_8x( &pll );
    Delay_ms ( 1000 );
    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