Measure RF signal strength with the help of LT5581 and PIC18F57Q43
Charting the invisible: RF meters in action
Published Feb 13, 2024
Click board™
RF Meter 3 Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Dive into the world of RF meters, where you'll learn to measure invisible radio frequency waves and harness their potential for various applications
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Hardware Overview
How does it work?
RF Meter 3 Click is based on the LT5581, an RMS power detector with a 40dB dynamic range from Analog Devices. Users can use an RF power meter like this one to measure and document pulsed RF signals, noise-like signals, and pseudorandom signals. The RMS detector uses a proprietary technique to accurately measure the RF power from 2GHz up to 2.6GHz. Moreover, the LT5581 offers exceptional accuracy over its wide operating temperature range. Its RMS measurement capability provides accurate RF power readings within ±0.2dB regardless of waveforms with high crest-factor modulated content, multi-carrier, or multitone. The LT5581 combines a proprietary
high-speed power measurement subsystem with an internal 150kHz low pass averaging filter and an output voltage buffer in a completely integrated solution to achieve an accurate average power measurement of the high crest factor modulated RF signals. The resulting output voltage is directly proportional to the average RF input power in dBm. This Click board™ uses two mikroBUS™ pins for direct control. The Enable pin, labeled as EN and routed to the CS pin of the mikroBUS™ socket, optimizes power consumption and is used for power ON/OFF purposes (Shutdown feature). When its Enable input pin is pulled low, the LT5581 draws a typical shutdown current of 0.2uA and a
maximum of 6uA. As mentioned before, the resulting output voltage of the LT5581 is sent directly to an analog pin of the mikroBUS™ socket labeled as AN for MCU to read further and analyze RF signal data. 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
PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive
mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI
GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
48
RAM (Bytes)
8196
You complete me!
Accessories
Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.
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 Curiosity Nano with PIC18F57Q43 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 RF Meter 3 Click driver.
Key functions:
rfmeter3_enable_device- This function enables device by setting EN pin to HIGH logic level.rfmeter3_disable_device- This function disables device by setting EN pin to LOW logic level.rfmeter3_get_rf_input_power- This function reads the voltage from AN pin and converts it to RF input power in dBm.
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 RF Meter 3 Click Example.
*
* # Description
* This example demonstrates the use of RF Meter 3 click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and enables the click board.
*
* ## Application Task
* Measures the RF input signal power in dBm and displays the results on the USB UART every 100ms.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "rfmeter3.h"
static rfmeter3_t rfmeter3; /**< RF Meter 3 Click driver object. */
static log_t logger; /**< Logger object. */
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
rfmeter3_cfg_t rfmeter3_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.
rfmeter3_cfg_setup( &rfmeter3_cfg );
RFMETER3_MAP_MIKROBUS( rfmeter3_cfg, MIKROBUS_1 );
if ( ADC_ERROR == rfmeter3_init( &rfmeter3, &rfmeter3_cfg ) )
{
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
rfmeter3_enable_device ( &rfmeter3 );
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
float rfmeter3_rf_input_power = 0;
if ( RFMETER3_ERROR != rfmeter3_get_rf_input_power ( &rfmeter3, &rfmeter3_rf_input_power ) )
{
log_printf( &logger, " RF Input Power: %.2f dBm\r\n", rfmeter3_rf_input_power );
Delay_ms( 100 );
}
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
