Intermediate
30 min

Achieve galvanic isolation of the SPI interface with MAX22345 and PIC18F57Q43

Completely isolated SPI interface

SPI Isolator 6 Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

SPI Isolator 6 Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Create a communication bridge between devices with different power domains

A

A

Hardware Overview

How does it work?

SPI Isolator 6 Click is based on the MAX22345, a four-channel digital isolator with a maximum data rate of 200Mbps from Analog Devices. The MAX22345 provides galvanic isolation for digital signals transmitted between two ground domains and can withstand up to 784Vpeak of continuous isolation and up to 3.75kVRMS for up to 60 seconds. Besides, Analog's proprietary process technology offers the low-power operation, high electromagnetic interference (EMI) immunity, and stable temperature performance.

Both power pins' wide supply voltage range allows the MAX22345 to be used for level translation and isolation. Because this Click board™ represents an isolator for SPI communication, it logically communicates with the MCU precisely through that communication. As already mentioned, the MAX22345 has two power pins for the A and B isolation sides, where it is possible to supply its B side with external voltage in the range of 1.7 to 5.5V by applying it to the terminal marked with VCC_EXT. In addition to the external power supply terminal,

this Click board™ also possesses another two terminals to which the isolated SPI data communication lines are routed. 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. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used for further development.

spi-isolator-6-click-hardware-overview

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.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

default

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.

Curiosity Nano Base for Click boards accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
PD4
CS
SPI Clock
PC6
SCK
SPI Data OUT
PC5
MISO
SPI Data IN
PC4
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

SPI Isolator 6 Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Curiosity Nano with PICXXX Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
PIC18F57Q43 Curiosity MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

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 SPI Isolator 6 Click driver.

Key functions:

  • spiisolator6_generic_write This function writes a desired number of data bytes by using SPI serial interface.

  • spiisolator6_generic_read This function writes and then reads a desired number of data bytes by using SPI serial interface.

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 SPIIsolator6 Click example
 *
 * # Description
 * This example demonstrates the use of SPI Isolator 6 Click board by reading the
 * device ID of the connected Accel 22 Click board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and logger.
 *
 * ## Application Task
 * Reads and checks the device ID of the connected Accel 22 Click board, and displays the
 * results on the USB UART approximately once per second.
 *
 * @note
 * Make sure to provide VCC power supply on VCC-EXT pin.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "spiisolator6.h"

static spiisolator6_t spiisolator6;
static log_t logger;

/**
 * @brief SPI Isolator 6 get accel 22 device id function.
 * @details This function reads and checks the device ID of the connected Accel 22 Click board.
 * @param[in] ctx : Click context object.
 * See #spiisolator6_t object definition for detailed explanation.
 * @return None.
 * @note None.
 */
void spiisolator6_get_accel22_device_id ( spiisolator6_t *ctx );

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    spiisolator6_cfg_t spiisolator6_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.
    spiisolator6_cfg_setup( &spiisolator6_cfg );
    SPIISOLATOR6_MAP_MIKROBUS( spiisolator6_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == spiisolator6_init( &spiisolator6, &spiisolator6_cfg ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void )
{
    spiisolator6_get_accel22_device_id ( &spiisolator6 );
    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;
}

void spiisolator6_get_accel22_device_id ( spiisolator6_t *ctx )
{
    #define DEVICE_NAME             "Accel 22 Click"
    #define DEVICE_SPI_READ_REG     0x0B
    #define DEVICE_REG_ID           0x00
    #define DEVICE_ID               0xAD
    uint8_t data_in[ 2 ] = { DEVICE_SPI_READ_REG, DEVICE_REG_ID };
    uint8_t device_id;
    if ( SPIISOLATOR6_OK == spiisolator6_generic_read ( ctx, data_in, 2, &device_id, 1 ) )
    {
        log_printf( &logger, "\r\n %s\r\n", ( char * ) DEVICE_NAME );
        if ( DEVICE_ID == device_id )
        {
            log_printf ( &logger, " Device ID: 0x%.2X\r\n", ( uint16_t ) device_id );
        }
        else
        {
            log_error( &logger, " Wrong Device ID: 0x%.2X", ( uint16_t ) device_id );
        }
    }
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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