Analog MUX 3 Click

How does it work?

Analog MUX 3 Click uses the ADG738, a CMOS 8-channel analog matrix switch with a serially-controlled SPI interface from Analog Devices. The ADG738 can operate equally well as either multiplexer, demultiplexer, or switch array, providing more flexibility. It also features a low on-resistance closely matched between switches and very flat over the entire signal range. During the Power-Up of the ADG738, all switching channels will be in the OFF condition, and the internal shift register will contain all zeros and remains so until a valid write takes place. All channels exhibit ‘break-before-make switching action preventing momentary shorting when switching channels.

Each bit of the 8-bit serial word corresponds to one switch of the device. Internal switching channels are independently controlled by an individual bit, providing an option of having any, all, or none of the switches activated. All of the input channels of the multiplexer can be easily connected to a nine pole spring action block terminal, without having to use any additional tools, such as screwdrivers, while the output pin from the multiplexer is routed to the AN pin on the mikroBUS™ socket.

When changing the switch conditions, a new 8-bit word is written to the input shift register. Some of the bits may be the same as the previous write cycle, as the user may not wish to change the state of some switches. To minimize glitches on these switches’ output, the ADG738 cleverly compares the state of switches from the previous write cycle. If the switch is already in the ON state and needs to stay in that condition, there will be minimal glitches on the switch’s output.

Analog MUX 3 Click communicates with MCU using the SPI serial interface compatible with standard SPI, QSPI™, MICROWIRE™, DSP interface standards, and operates at clock rates up to 30MHz. Also, this Click board™ has a Reset pin routed to the RST pin on the mikroBUS™ socket, which clears the input register and turns all switches to the OFF condition.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to properly use the SPI communication lines. 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.

Specifications

Pinout diagram

This table shows how the pinout on Analog MUX 3 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog Signal	AN	1	AN	PWM	16	NC
Reset	RST	2	RST	INT	15	NC
SPI Chip Select	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
SPI Data OUT	SDO	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Analog MUX 3 Click electrical specifications

Software Support

We provide a library for the Analog Mux 3 Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on mikroE github account.

Library Description

This library contains API for Analog Mux 3 Click driver.

Key functions:

• analogmux3_cfg_setup – Config Object Initialization function.
• analogmux3_init – Initialization function.
• analogmux3_default_cfg – Click Default Configuration function.

Examples description

This is an example that demonstrates the use of the Analog MUX 3 click board. This application controls the multiplexing of a single input channel with an eight-channel matrix switch.

The demo application is composed of two sections :

void application_task ( void ) {
    for ( uint8_t ch_pos = ANALOGMUX3_SET_CHANNEL_0; ch_pos <= ANALOGMUX3_SET_CHANNEL_7; ch_pos++ ) {
        analogmux3_set_channel( &analogmux3, ch_pos );
        Delay_ms( 1000 );
        
        uint16_t analogmux3_an_value = 0;
    
        log_printf( &logger, "   CHANNEL    : AN%u     rn", ch_pos );
        log_printf( &logger, "- - - - - - - - - - - - - rn" );

        if ( analogmux3_read_an_pin_value ( &analogmux3, &analogmux3_an_value ) != ADC_ERROR ) {
            log_printf( &logger, "   ADC Value  : %urn", analogmux3_an_value );
        }
    
        float analogmux3_an_voltage = 0;

        if ( analogmux3_read_an_pin_voltage ( &analogmux3, &analogmux3_an_voltage ) != ADC_ERROR ) {
            log_printf( &logger, "   AN Voltage : %.3f V rn", analogmux3_an_voltage );
        }
        
        log_printf( &logger, "-------------------------rn" );
    }   
}

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on mikroE github account.

Other mikroE Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.AnalogMux3

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

mikroSDK

This Click board™ is supported with mikroSDK – MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.