Unleash the beauty of analog side of a signal with DAC60508 and PIC18F2458

Bridging the binary abyss

Published Dec 29, 2023

Click board™

DAC 12 Click

Dev Board

EasyPIC v7a

Compiler

NECTO Studio

MCU

PIC18F2458

Convert discrete digital values into continuous analog voltages, and enable accurate audio or visual signal representation

Hardware Overview

How does it work?

DAC 12 Click is based on the DAC60508, a low-power voltage-output 8-channel 12-bit digital-to-analog converter (DAC) from Texas Instruments. Each output channel in the DAC60508 consists of an R-2R ladder architecture, followed by an output buffer amplifier. It also includes a 2.5V, 5ppm/°C internal reference, eliminating the need for an external precision reference in most applications, and a user interface-selectable gain configuration that provides full-scale output voltages of 1.25V, 2.5V, or 5V. This Click board™ communicates with MCU through a flexible serial interface compatible

with SPI-type interfaces used on many microcontrollers and DSP controllers, with a maximum frequency of 50 MHz. The input data are written to the individual DAC data registers in straight binary format, where after a Power-On or a reset event, all DAC registers are set to a mid-scale code. Data written to the DAC data registers are initially stored in the DAC buffer registers. Data transfer from the DAC buffer registers to the active DAC registers can be configured immediately using the asynchronous mode or initiated by an LDAC trigger in synchronous mode. Once the DAC

active registers are updated, the DAC outputs change to new values. When the host reads from a DAC data register, the value held in the DAC buffer register is returned (not stored in the DAC active register). 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. Also, this 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 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.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

RST

SPI Chip Select

RA5

SPI Clock

RC3

SCK

SPI Data OUT

RC4

MISO

SPI Data IN

RC5

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

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.

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 v7a Access MB 2 - upright/background hardware assembly

NECTO Compiler Selection Step Image hardware assembly

Necto DIP image step 7 hardware assembly

EasyPIC PRO v7a Display Selection Necto Step 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.

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.

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".

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.

Software Support

Library Description

This library contains API for DAC 12 Click driver.

Key functions:

dac12_soft_reset - This function executes the software reset command
dac12_set_channel_value - This function sets the raw DAC value to the specific channels output
dac12_set_channel_voltage - This function sets the output voltage of the specific channels

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 DAC12 Click example
 *
 * # Description
 * This example demonstrates the use of DAC 12 click board by changing 
 * the outputs voltage level every 2 seconds.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and performs the click default configuration.
 *
 * ## Application Task
 * Changes the output voltage of all channels every 2 seconds and logs the voltage value on the USB UART.
 * It will go through the entire voltage range taking into account the number of steps which is defined below.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "dac12.h"

#define NUMBER_OF_STEPS    20  // The number of steps by which the entire voltage range will be divided. 

static dac12_t dac12;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    dac12_cfg_t dac12_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.
    dac12_cfg_setup( &dac12_cfg );
    DAC12_MAP_MIKROBUS( dac12_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == dac12_init( &dac12, &dac12_cfg ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    DAC12_SET_DATA_SAMPLE_EDGE;
    
    if ( DAC12_ERROR == dac12_default_cfg ( &dac12 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void )
{
    float step = DAC12_INTERNAL_VREF / NUMBER_OF_STEPS;
    float output_voltage = step;
    for ( uint8_t cnt = 0; cnt < NUMBER_OF_STEPS; cnt++ )
    {
        if ( DAC12_OK == dac12_set_channel_voltage ( &dac12, DAC12_SELECT_CHANNEL_ALL, output_voltage ) )
        {
            log_printf( &logger, " All channels output voltage set to %.3f V\r\n", output_voltage );
            output_voltage += step;
            Delay_ms( 2000 );
        }
    }
}

void main ( void )
{
    application_init( );

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

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