Create contactless switches for applications where physical contact is impractical or undesirable with NMH1000 and PIC18LF47K40
Hall-effect magnetic switch
Published Jan 23, 2024
Click board™
Hall Switch 3 Click
Dev. board
EasyPIC v7
Compiler
NECTO Studio
MCU
PIC18LF47K40
Detect changes in vertical magnetic fields and achieve unparalleled sensitivity to specific magnet orientations
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Hardware Overview
How does it work?
Hall Switch 3 Click is based on the NMH1000, a Hall-effect magnetic switch from NXP Semiconductor. The switch processes its input over the functional blocks that consist of a configurable state machine, an analog-to-voltage conversion of the input, and a comparison to generate the bi-state output. The output is arranged in a linear succession. The NMH1000 has a transducer that generates a small charge proportional to the
proximal magnetic flux density. The Hall-effect charge is converted to voltage and compared with the pre-defined threshold voltage. This determines the state of the switch's output. Hall Switch 3 Click uses a standard 2-wire I2C interface to communicate with the host MCU, supporting a clock frequency of up to 1MHz. The output of the switch, according to the pre-defined threshold, is available over the output OUT pin. This Click
board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.
Features overview
Development board
EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyPIC v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of
the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use various external power sources, including an external 12V power supply, 7-23V AC or 9-32V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B) connector. Communication options such as
USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from PIC10F, PIC12F, PIC16F, PIC16Enh, PIC18F, PIC18FJ, and PIC18FK families. EasyPIC v7 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)
128
Silicon Vendor
Microchip
Pin count
40
RAM (Bytes)
3728
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 EasyPIC v7 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 Hall Switch 3 Click Click driver.
Key functions:
hallswitch3_get_mag_data- This function is used to indicates a relative magnetic field strength.hallswitch3_set_out_data_rate- This function provides the capability for the user to override the fixed sample rate controlling the sleep-compare-Vout cycle time.hallswitch3_get_status- This function reads a status reporting of modes and selections.
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 Hall Switch 3 Click example
*
* # Description
* This example demonstrates the use of Hall Switch 3 Click board
* by reading and displaying the magnetic field strength value.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initialization of I2C module and log UART.
* After driver initialization, the app executes a default configuration.
*
* ## Application Task
* This example demonstrates the use of the Hall Switch 3 Click board.
* The demo application reads and displays the relative magnetic field strength value [Gaussian units]
* and detects when the magnetic field strength is not in the configured range.
* The results are sent to the UART terminal, where you can monitor their changes.
*
* @author Nenad Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "hallswitch3.h"
static hallswitch3_t hallswitch3;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
hallswitch3_cfg_t hallswitch3_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.
hallswitch3_cfg_setup( &hallswitch3_cfg );
HALLSWITCH3_MAP_MIKROBUS( hallswitch3_cfg, MIKROBUS_1 );
if ( I2C_MASTER_ERROR == hallswitch3_init( &hallswitch3, &hallswitch3_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( HALLSWITCH3_ERROR == hallswitch3_default_cfg ( &hallswitch3 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
int8_t mag_data = 0;
if ( HALLSWITCH3_OK == hallswitch3_get_mag_data( &hallswitch3, &mag_data ) )
{
log_printf( &logger, " Magnetic Field: %d [Gs]\r\n", ( int16_t ) mag_data );
if ( HALLSWITCH3_OUT_STATE_LOW == hallswitch3_check_mag_field( &hallswitch3 ) )
{
log_printf( &logger, " The switch is open.\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
