Achieve high-resolution inductance measurement capabilities with LDC1000 and PIC18F57Q43
Unlocking inductive secrets
Published Feb 13, 2024
Click board™
LDC1000 Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Accurately measure the inductance change caused by the presence or movement of conductive targets within its magnetic field
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Hardware Overview
How does it work?
LDC1000 Click is based on the LDC1000, a low-power inductance-to-digital converter from Texas Instruments. The LDC1000 simultaneously measures an LC resonator's impedance and resonant frequency by regulating the oscillation amplitude in a closed-loop configuration to a constant level while monitoring the energy the resonator dissipates. By monitoring the amount of power injected into the resonator, the LDC1000 can determine the impedance value and return it as a digital value. In addition, the LDC1000 can also measure the oscillation frequency of the LC circuit, used to determine the inductance of the LC circuit, also given in a digital format. The LDC1000 has a sub-micron resolution in short-range applications suitable for precise short-range measurements of conductive targets' position, motion, or composition. This Click board™ comes with a
detachable sensor (an LC tank comprising a 36-turn PCB coil and a 100pF 1% NPO capacitor). The LDC measures the inductance change that a conductive target causes when it moves into the inductor's AC magnetic field to provide information about the target's position over a sensor coil. The inductance shift is caused by eddy currents (circulating currents) generated in the target due to the sensor's magnetic field. These currents make a secondary magnetic field that opposes the sensor field, causing a shift in the observed inductance, used for precise positioning of the target as it moves laterally over the sensor coil. The LDC1000 communicates with MCU using the standard SPI serial interface with a maximum frequency of 4MHz. It also has an interrupt pin routed to the INT pin of the mikroBUS™ socket, which can be configured in three different ways by programming
the interrupt mode register. An interrupt pin can act as a proximity switch with programmable hysteresis, a wake-up feature, or a data-ready pin indicating a valid condition for new data availability. Inductive sensing of this LDC is highly reliable where harsh conditions don't hinder the performance of LDC1000. Alongside the detachable sensor, the onboard INA and INB pins allow you to replace the provided sensor and solder your own. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the I/O level 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
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 LDC1000 Click driver.
Key functions:
ldc1000_get_proximity_data- This function reads the proximity dataldc1000_get_inductance_data- This function reads the inductance dataldc1000_get_int_input- This function reads the input voltage from the INT pin
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 Ldc1000 Click example
*
* # Description
* This example showcases how to initialize and configure the logger and click modules and
* read and display proximity and impendance data.
*
* The demo application is composed of two sections :
*
* ## Application Init
* This function initializes and configures the logger and click modules. Configuration data
* is written to the: rp maximum/minimum, sensor frequency, LDC/Clock/Power registers.
*
* ## Application Task
* This function reads and displays proximity and impendance data every 10th of a second.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "ldc1000.h"
// ------------------------------------------------------------------ VARIABLES
static ldc1000_t ldc1000;
static log_t logger;
static uint16_t old_proximity;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( )
{
log_cfg_t log_cfg;
ldc1000_cfg_t cfg;
old_proximity = 0;
/**
* 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.
ldc1000_cfg_setup( &cfg );
LDC1000_MAP_MIKROBUS( cfg, MIKROBUS_1 );
ldc1000_init( &ldc1000, &cfg );
Delay_ms( 100 );
ldc1000_default_cfg( &ldc1000 );
Delay_ms( 100 );
}
void application_task ( )
{
uint16_t proximity;
float inductance;
proximity = ldc1000_get_proximity_data( &ldc1000 );
inductance = ldc1000_get_inductance_data( &ldc1000 );
if ( ( ( proximity - old_proximity ) > LDC1000_SENSITIVITY ) &&
( ( old_proximity - proximity ) > LDC1000_SENSITIVITY ) )
{
log_printf( &logger, " * Proximity: %d \r\n", proximity );
log_printf( &logger, " * Impendance: %f uH\r\n", inductance );
old_proximity = proximity;
log_printf( &logger, "--------------------\r\n" );
Delay_ms( 100 );
}
}
void main ( )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
