Create general-purpose data selector with TMUX1308 and PIC18F24K50

Analog multiplexer

Published Nov 01, 2023

Click board™

Analog MUX 4 Click

Dev. board

EasyPIC v8

Compiler

NECTO Studio

MCU

PIC18F24K50

Choose one of many analog data inputs

Hardware Overview

How does it work?

Analog MUX 4 Click is based on the TMUX1308, a general-purpose 8:1 single-ended CMOS analog multiplexer from Texas Instruments. The TMUX1308 multiplexer allows for multiple inputs/sensors to be monitored with a single AN pin of the mikroBUS™ socket supporting bidirectional analog and digital signals ranging from 0 to 5V. It has an internal injection current control eliminating the need for external diode and resistor networks to protect the switch, keeping the input signals within the supply voltage. The internal injection current control circuitry allows signals on disabled signal paths to exceed the supply voltage without affecting the signal of the enabled signal path.

Alongside internal injection current control, the TMUX1308 also has another protection feature, called Break-before-make delay, which represents a safety feature preventing two inputs from connecting when the device is switching. The output first breaks from the ON-state switch before connecting with the next ON-state switch. This time delay between the break and the make is known as the break-before-make delay. This Click board™ communicates with MCU using several GPIO pins. It can be enabled or disabled through the EN pin of the mikroBUS™ socket, hence, offering a switch operation to turn ON/OFF power delivery to the TMUX1308. It also provides three address signals, labeled from A0 to A2, that control

the switch configuration and determine the activation of the desired analog input channel based on their setup. Also, each analog input has a jumper for its hardware activation or deactivation and capacitors for additional filtering of the input channels. 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, as a reference, for further development.

Features overview

Development board

EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. 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, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board 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 DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC 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.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

Analog Signal

RA3

Switch Control 2

RA0

RST

Enable

RA5

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

Switch Control 0

RC1

PWM

Switch Control 1

RB1

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

EasyPIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v8 as your development board.

NECTO Output Selection Step Image hardware assembly

In the advanced settings, pay special attention to the Redirect standard output field. By default, it is set to Application output as the method of displaying final results. To show results via a UART terminal, select the “UART” option in that field and click the “SAVE” button. You will be returned to the Compiler field, and now you can move on to the next step by pressing the “NEXT” button.

LTE IoT 5 Click front image hardware assembly

LTE IoT 5 Click complete accessories setup image hardware assembly

EasyPIC v8 28pin-DIP Access - upright/background hardware assembly

NECTO Compiler Selection Step Image hardware assembly

Necto DIP image step 7 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 Analog MUX 4 Click driver.

Key functions:

analogmux4_enable_input This function enables analog inputs.
analogmux4_read_an_pin_voltage This function reads the results of the AD conversion of the AN pin and converts them to a proportional voltage level.
analogmux4_set_input_channel This function sets the analog input channel.

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 Analog MUX 4 Click Example.
 *
 * # Description
 * This example demonstrates the use of Analog MUX 4 Click board.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and enables the analog inputs.
 *
 * ## Application Task
 * Reads and displays the voltage of all channels on the USB UART approximately once per second.
 *
 * @note
 * The channel's voltage will "float" when the voltage source is not connected to it.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "analogmux4.h"

static analogmux4_t analogmux4;   /**< Analog MUX 4 Click driver object. */
static log_t logger;              /**< Logger object. */

void application_init ( void )
{
    log_cfg_t log_cfg;                /**< Logger config object. */
    analogmux4_cfg_t analogmux4_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.
    analogmux4_cfg_setup( &analogmux4_cfg );
    ANALOGMUX4_MAP_MIKROBUS( analogmux4_cfg, MIKROBUS_1 );
    if ( ADC_ERROR == analogmux4_init( &analogmux4, &analogmux4_cfg ) )
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }
    
    analogmux4_enable_input ( &analogmux4 );
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    float analogmux4_an_voltage = 0;
    
    for ( uint8_t cnt = ANALOGMUX4_CHANNEL_0; cnt <= ANALOGMUX4_CHANNEL_7; cnt++ )
    {
        analogmux4_set_input_channel ( &analogmux4, cnt );
        if ( ADC_ERROR != analogmux4_read_an_pin_voltage ( &analogmux4, &analogmux4_an_voltage ) ) 
        {
            log_printf( &logger, " AN%u voltage : %.3f V\r\n", ( uint16_t ) cnt, analogmux4_an_voltage );
        }
    }
    log_printf( &logger, "\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