Encode analog signal into a binary code easily with ADS7828 and PIC18F57Q43
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Published Feb 13, 2024
Click board™
ADC 12 Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Ready to take on even the most complex designs? Our ADC is up to the challenge!
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Hardware Overview
How does it work?
ADC 12 Click is based on the ADS7828, a low-power 12-bit data acquisition device with a serial I2C interface and an 8-channel multiplexer from Texas Instruments. The architecture of the ADS7828, which is a classic Successive Approximation Register (SAR) A/D converter, is based on capacitive redistribution that inherently includes a sample-and-hold function. It has an integrated I2C input and output port with screw terminal connectors for each analog input channel. An internally generated free-running clock controls it. When the ADS7828 is not performing conversions or being addressed, it keeps the A/D converter core powered off, and the internal clock does not operate. When the A/D converter enters the Hold mode, the voltage on the selected channel pin of the input
terminal is captured on the internal capacitor array. The input current on the analog inputs depends on the conversion rate of the device. During the sample period, the source must charge the internal sampling capacitor. There is no further input current after the capacitor has been fully charged. The amount of charge transfer from the analog source to the converter is a function of the conversion rate. ADC 12 Click communicates with MCU using the standard I2C 2-Wire interface with a frequency of up to 100kHz in the Standard, up to 400kHz in the Fast, and up to 3.4MHz in the High-Speed mode. It also allows the choice of the last two least significant bits (LSB), A0 and A1, by positioning SMD jumpers labeled ADDR SEL to an appropriate position marked as 0 and 1.
This Click board™ also possesses a jumper for selecting the reference voltage labeled as VREF SEL. The ADS7828 can operate with an internal 2.5V reference or an external reference (in this case, logic voltage level VCC), which can be selected by positioning SMD jumpers to an appropriate position marked as INT and EXT. 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
PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive
mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI
GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
48
RAM (Bytes)
8196
You complete me!
Accessories
Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.
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 ADC 12 Click driver.
Key functions:
void adc12_send_cmd ( uint8_t cmd_byte );- Function is used to configure the device.uint16_t adc12_single_ended ( uint8_t chan, uint16_t v_ref );- Function is used to get raw ADC value.uint16_t adc12_differential ( uint8_t chan, uint16_t v_ref );- Function is used to get raw ADC value.
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 ADC12 Click example
*
* # Description
* This example demonstrates the use of ADC 12 click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and sets the input and power-down modes.
*
* ## Application Task
* Reads the RAW ADC data and converts it to voltage in milivolts and displays
* both values on the USB UART every second.
*
* @note
* With internal reference voltage set the click measures up to 2500 mV.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "adc12.h"
static adc12_t adc12;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
adc12_cfg_t adc12_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.
adc12_cfg_setup( &adc12_cfg );
ADC12_MAP_MIKROBUS( adc12_cfg, MIKROBUS_1 );
err_t init_flag = adc12_init( &adc12, &adc12_cfg );
if ( init_flag == I2C_MASTER_ERROR )
{
log_error( &logger, " Application Init Error. " );
log_info( &logger, " Please, run program again... " );
for ( ; ; );
}
adc12_set_sd_mode ( &adc12, ADC12_CMD_SD_SINGLE_END );
adc12_set_pd_mode( &adc12, ADC12_CMD_PD_IRON_ADON );
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
uint16_t raw_adc;
float voltage;
adc12_read_raw_data ( &adc12, ADC12_SINGLE_END_CH0, &raw_adc );
adc12_read_voltage ( &adc12, ADC12_SINGLE_END_CH0, ADC12_INTERNAL_VREF, &voltage );
log_printf( &logger, " RAW ADC: %u \r\n", raw_adc );
log_printf( &logger, " Voltage from Channel 0: %.2f mV \r\n", voltage );
log_printf( &logger, " ---------------------------\r\n" );
Delay_ms( 1000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
