Generate high-frequency clock output with ICS501 and PIC18F2550
Phase-Locked Loop (PLL) mechanism
Published Nov 01, 2023
Click board™
PLL Click
Dev Board
EasyPIC v8
Compiler
NECTO Studio
MCU
PIC18F2550
Generate highly stable and coherent high-frequency signals for applications requiring tight synchronization and minimal phase noise
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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
EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any
circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.
Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
32
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
2048
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 EasyPIC v8 as your development board.
Track your results in real time
Application Output
After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.
Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.
In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".
The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.
Software Support
Library Description
This library contains API for PLL Click driver.
Key functions:
pll_set_clock_output- This function settings clock outputpll_set_pll_4x- This function settings PLL x4pll_set_pll_6x- This function settings PLL x6
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 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
Additional Support
Resources
Category:Clock generator
