Intermediate
30 min
0

Convert the countless reams of digital information into analog signals using DAC104S085 and PIC18F4685

From digits to signals

DAC 6 Click with EasyPIC v7

Published Aug 18, 2023

Click board™

DAC 6 Click

Development board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18F4685

As digital information converges into analog clarity, our solution fosters connectivity by enabling effective communication between systems, unlocking a realm of data transformation possibilities

A

A

Hardware Overview

How does it work?

DAC 6 Click is based on the DAC104S085, 10-bit resolution micro-power QUAD digital-to-analog converter with rail-to-rail output from Texas Instruments. The DAC104S085 is manufactured on a CMOS process with an architecture consisting of switches and resistor strings followed by an output buffer. The reference voltage is applied at the VREFIN pin and is shared by all four DAC outputs (A, B, C, and D). This string consists of 1024 equal-valued resistors with a switch at each junction of two resistors, plus a switch to the ground. The code loaded into the DAC register determines which switch is closed, connecting the proper node to the amplifier. The voltage reference pin of the DAC104S085 is not buffered, and because of that, it is recommended to drive the VREFIN pin by a voltage source with a low output impedance.

This is accomplished using the MCP1501, a low drift bandgap-based voltage reference from a Microchip capable of sinking and sourcing 20mA of current. The bandgap uses chopper-based amplifiers, effectively reducing the drift to zero. The reference voltage range which can be applied to the VREFIN pin is 1V to VCC (in this case, 2.048V), providing the widest possible output dynamic range with a maximum output current of 11mA per channel. The DAC 6 Click communicates with MCU using the 3-Wire SPI serial interface compatible with standard SPI, QSPI™, and MICROWIRE™ and operates at clock rates up to 40 MHz. To use the full dynamic range of the DAC104S085, it is possible to connect the VREFIN pin to the supply voltage VCC. Because of its low power consumption, a reference source may be

used as the reference input or the supply voltage, which results in accuracy and stability. The reference voltage level can be selected by positioning the SMD jumper labeled as VREF SEL to an appropriate position, selecting between a value of 2.048V and the supply voltage VCC. This Click Board™ uses the SPI communication interface with both 3.3V and 5V. The onboard SMD jumper labeled VCC SEL allows voltage selection for interfacing with 3.3V and 5V MCUs. More information about the DAC104S085’s functionality, electrical specifications, and typical performance can be found in the attached datasheet. However, the Click board™ comes equipped with a library that contains easy-to-use functions and a usage example that may be used as a reference for the development.

DAC 6 Click top side image
DAC 6 Click bottom side image

Features overview

Development board

EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. 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 v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of

the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block 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-B (USB-B) 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 v7 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 v7 horizontal image

Microcontroller Overview

MCU Card / MCU

PIC18F4685

Architecture

PIC

MCU Memory (KB)

96

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

3328

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
RE0
CS
SPI Clock
RC3
SCK
NC
NC
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
1

Take a closer look

Schematic

DAC 6 Click Schematic schematic

Step by step

Project assembly

EasyPIC v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7 as your development board.

EasyPIC v7 front image hardware assembly
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyPIC v7 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 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 DAC 6 Click driver.

Key functions:

  • dac6_set_output - Function is used to set operation mode output channel and level

  • dac6_write_data - Sends 16-bit data to the device's input shift register.

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 
 * \brief Dac6 Click example
 * 
 * # Description
 * DAC 6 click carries 12-bit buffered Digital-to-Analog Converter. It converts digital value 
 * to the corresponding voltage level using external voltage reference. 
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initalizes SPI driver.
 * 
 * ## Application Task  
 * This example shows capabilities of DAC 6 click by changeing
 * output values from 0 to the maximum output range on all four channels.
 * Output voltage is calculated by using the equation : 
 * Vout = Vrefin * (set_out / 4095).
 * 
 *
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "dac6.h"

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

static dac6_t dac6;
static log_t logger;

static uint16_t n_cnt;
static float v_out;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    dac6_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.

    dac6_cfg_setup( &cfg );
    DAC6_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    dac6_init( &dac6, &cfg );
}

void application_task ( void )
{
    for ( n_cnt = 0; n_cnt < 4096; n_cnt += 315 )
    {
        dac6.chan    = DAC6_CHANNEL_A;
        dac6.op_mod  = DAC6_WRITE_SPEC_UPDATE_OUTPUT;
        dac6.v_ref   = DAC6_V_REF_2048;
        dac6.set_out = n_cnt;
        
        v_out = dac6_set_output( &dac6 );
        
        log_printf( &logger, " Channel  A : VOUT ~ %.2f mV\r\n", v_out );
        log_printf( &logger, "--------------------\r\n" );
        Delay_ms( 5000 );
    }

    for ( n_cnt = 0; n_cnt < 4096; n_cnt += 315 )
    {
        dac6.chan    = DAC6_CHANNEL_B;
        dac6.op_mod  = DAC6_WRITE_SPEC_UPDATE_OUTPUT;
        dac6.v_ref   = DAC6_V_REF_2048;
        dac6.set_out = n_cnt;
        
        v_out = dac6_set_output( &dac6 );
        
        log_printf( &logger, " Channel  B : VOUT ~ %.2f mV\r\n", v_out );
        log_printf( &logger, "--------------------\r\n" );
        Delay_ms( 5000 );
    }
    
    for ( n_cnt = 0; n_cnt < 4096; n_cnt += 315 )
    {
        dac6.chan    = DAC6_CHANNEL_C;
        dac6.op_mod  = DAC6_WRITE_SPEC_UPDATE_OUTPUT;
        dac6.v_ref   = DAC6_V_REF_2048;
        dac6.set_out = n_cnt;
        
        v_out = dac6_set_output( &dac6 );
        
        log_printf( &logger, " Channel  C : VOUT ~ %.2f mV\r\n", v_out );
        log_printf( &logger, "--------------------\r\n" );
        Delay_ms( 5000 );
    }

    for ( n_cnt = 0; n_cnt < 4096; n_cnt += 315 )
    {
        dac6.chan    = DAC6_CHANNEL_D;
        dac6.op_mod  = DAC6_WRITE_SPEC_UPDATE_OUTPUT;
        dac6.v_ref   = DAC6_V_REF_2048;
        dac6.set_out = n_cnt;
        
        v_out = dac6_set_output( &dac6 );
        
        log_printf( &logger, " Channel  D : VOUT ~ %.2f mV\r\n", v_out );
        log_printf( &logger, "--------------------\r\n" );
        Delay_ms( 5000 );
    }
    
    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

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


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

Additional Support

Resources