30 min

Achieve galvanic isolation of the SPI interface with MAX22345 and TM4C1294NCPDT

Completely isolated SPI interface

SPI Isolator 6 Click with Fusion for ARM v8

Published Mar 09, 2023

Click board™

SPI Isolator 6 Click

Development board

Fusion for ARM v8


NECTO Studio



Create a communication bridge between devices with different power domains



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.


Features overview

Development board

Fusion for ARM v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different ARM® Cortex®-M based MCUs regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. 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, Fusion for ARM v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the Fusion for ARM v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it 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 HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for ARM 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.

Fusion for ARM v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor

Texas Instruments

Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

SPI Chip Select
SPI Clock
Power Supply
Power Supply

Take a closer look


SPI Isolator 6 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for ARM v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN 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 Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

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.

UART Application Output Step 1

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.

UART Application Output Step 2

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".

UART Application Output Step 3

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.

UART Application Output Step 4

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

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * @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 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

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 );
            log_error( &logger, " Wrong Device ID: 0x%.2X", ( uint16_t ) device_id );

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

Additional Support