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Convert multiple analog signals into digital data with MCP3204 and PIC18F25K42

4-channel 12-bit ADC with SPI interface

ADC Click with EasyPIC v7a

Published Nov 01, 2023

Click board™

ADC Click

Development board

EasyPIC v7a

Compiler

NECTO Studio

MCU

PIC18F25K42

Help electronics understand and work with information from the real world

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Hardware Overview

How does it work?

ADC Click is based on the MCP3204, a 4-channel 12-bit A/D converter with SPI serial interface from Microchip. The MCP3204 contains an input channel selection multiplexer (CH0, CH1, CH2, CH3) which for reference can use the VCC (3.3V or 5V) or a 4.096V of the MCP1541 voltage reference from Microchip. The voltage reference determines the analog voltage range and can be selected via REFERENCE onboard jumper. To connect the

analog voltages to the ADC Click, utilize the four labeled terminals CH0-3 along with two GND terminals for referencing the ground. Each analog input pin goes through the MCP6284, a 5MHz rail-to-rail OpAmp from Microchip. The ADC Click uses a standard 4-Wire SPI serial interface to communicate with the host MCU, supporting both 0 and 3 of the SPI modes and operating at clock rates of up to 2MHz. Communication with the ADC

Click is initiated by bringing the CS line LOW. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR 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.

ADC Click hardware overview image

Features overview

Development board

EasyPIC v7a is the seventh generation of PIC development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as the first-ever embedded debugger/programmer over USB-C. 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 v7a allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of the EasyPIC v7a 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 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-C (USB-C) 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 v7a 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.

EasyPIC v7a double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
RA5
CS
SPI Clock
RC3
SCK
SPI Data OUT
RC4
MISO
SPI Data IN
RC5
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
2

Take a closer look

Schematic

ADC Click Schematic schematic

Step by step

Project assembly

EasyPIC v7a front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7a as your development board.

EasyPIC v7a front image hardware assembly
LTE IoT 5 Click front image hardware assembly
MCU DIP 28 hardware assembly
LTE IoT 5 Click complete accessories setup image hardware assembly
EasyPIC v7a Access MB 2 - 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 DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step 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 ADC Click driver.

Key functions:

  • adc_get_single_ended_ch - Get Single-Ended Channel function

  • adc_get_differential_ch - Get Pseudo-Differential Pair function

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 ADC Click example
 *
 * # Description
 * This example demonstrates the use of ADC Click board.
 * The all channels can be configured as single-ended or pseudo-differential
 * pair.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes SPI driver, performs the reference voltage selection and
 * initializes UART console for results logging.
 *
 * ## Application Task
 * Reads voltage level of channels 0 and 1 in the both configurations,
 * single-ended and pseudo-differential pair, every 1 second.
 * All channels results will be calculated to millivolts [mV].
 *
 * *note:*
 * In single-ended mode the all channels must be in the range from Vss (GND)
 * to Vref (3V3 by default).
 * In pseudo-differential mode the IN- channel must be in the range from
 * (Vss - 100mV) to (Vss + 100mV). The IN+ channel must be in the range from
 * IN- to (Vref + IN-).
 * If any of conditions are not fullfilled, the device will return 0 or Vref
 * voltage level, and measurements are not valid.
 *
 * \author Nemanja Medakovic
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "adc.h"


// ------------------------------------------------------------------ VARIABLES

static adc_t adc;
static log_t logger;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init( void )
{
    log_cfg_t log_cfg;
    adc_cfg_t cfg;

    /** 
     * 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.

    adc_cfg_setup( &cfg );
    ADC_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    adc_init( &adc, &cfg );
}

void application_task( void )
{
    adc_get_single_ended_ch( &adc, ADC_CH0_OR_CH01 );
    adc_get_single_ended_ch( &adc, ADC_CH1_OR_CH10 );
    adc_get_single_ended_ch( &adc, ADC_CH2_OR_CH23 );
    adc_get_single_ended_ch( &adc, ADC_CH3_OR_CH32 );
    adc_get_differential_ch( &adc, ADC_CH0_OR_CH01 );

    log_printf( &logger, "* CH0 = %u mV\r\n", adc.ch0 );
    log_printf( &logger, "* CH1 = %u mV\r\n", adc.ch1 );
    log_printf( &logger, "* CH2 = %u mV\r\n", adc.ch2 );
    log_printf( &logger, "* CH3 = %u mV\r\n", adc.ch3 );
    log_printf( &logger, "* CH0 - CH1 = %d mV\r\n", adc.ch01 );
    log_printf( &logger, "-----------------------------\r\n" );

    Delay_ms( 1000 );
}

void main( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}


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

Additional Support

Resources