Set the standard for ultra-low voltage comparison using MAX40000 and PIC18F57Q43
Ultra-efficient voltage comparator
Published Feb 13, 2024
Click board™
Nano Power 2 Click
Dev Board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Detecting voltage differences becomes effortless with our nanoPower voltage comparator, offering efficient monitoring for various applications
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Hardware Overview
How does it work?
Nano Power 2 Click is based on the MAX40000, a nanoPower comparator with built-in reference from Analog Devices. This company offers several variants of the same IC, of which the used IC variant offers reference voltage of 1.2V on one of its pins. This reference voltage can be used at the comparator input, providing an accurate reference voltage throughout the fully operational temperature range, if required by the custom application. The IC itself requires a very low number of external components. It has two input pins, used as the comparator inputs. Each of these inputs can use -0.2V up to VCC + 0.2V. The VCC is the power supply voltage, and it can be selected via the SMD jumper labeled as LOGIC, between the 3.3V and 5V rails from the mikroBUS™. One of the comparator inputs, labeled as IM on the MAX40000 IC, is routable to either the onboard potentiometer (P1) or the REF pin of the IC, which provides the referent voltage of 1.2V. The routing can be done by another SMD jumper, labeled as REF SEL. The second comparator input (labeled as IP on the MAX40000 IC) is routed to the second
onboard potentiometer (P2). Both potentiometers can be used to set any voltage between the GND and VCC, which is selected by the LOGIC jumper, as described above. As mentioned before, the comparator has two inputs. One of them it is the inverting input and it is labeled as IM. The other input is a non-inverting input, labeled as IP. When the IP voltage becomes higher than the IM voltage, the output state becomes logic HIGH; otherwise, the output is set to a LOW state. A special case is when both voltages are very close, or at the same level, at any given moment. This would result in an appearance of oscillation at the output due to noise or parasitic feedback. To cope with this problem, an internal hysteresis of ±2.5mV is applied. The output of the MAX40000 IC is routed to the mikroBUS™ INT pin, labeled as OUT on the Click board™. The output stage employs a unique break-before-make topology, capable of rail-to-rail operation with up to ±2mA loads. The output stage also uses a unique design, which minimizes supply current surges when the switching occurs, resulting in very clean output
and low EM radiation. The MAX40000 has a push-pull output stage topology, which can both sink and source the current. Working with the Nano Power 2 click is very easy and straightforward. Only a single pin is used, which can be used to either trigger an interrupt (therefore it is routed to the INT pin), or its status can be read via the input pin of the host MCU. However, MikroElektronika provides a library that contains a function which can be used for simplified control of the Nano Power 2 click. The library also contains an example application, which demonstrates the use of the function. This example application can be used as a reference for custom designs. 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
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
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 via Debug Mode
1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.
2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.
Software Support
Library Description
This library contains API for Nano Power 2 Click driver.
Key functions:
nanopower2_check_output- Function gets output voltage from comparator
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 Nano Power 2 Click example
*
* # Description
* This application logs the comparators output value on USBUART.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes GPIO driver.
*
* ## Application Task
* Checks the comparator's output and logs output value on USBUART.
*
* \author Petar Suknjaja
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "nanopower2.h"
// ------------------------------------------------------------------ VARIABLES
static nanopower2_t nanopower2;
static log_t logger;
uint8_t out_check;
uint8_t out_check_prev;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
nanopower2_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.
nanopower2_cfg_setup( &cfg );
NANOPOWER2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
nanopower2_init( &nanopower2, &cfg );
log_printf( &logger, "NANO POWER 2 is initialized\r\n" );
out_check_prev = 2;
}
void application_task ( void )
{
out_check = nanopower2_check_output( &nanopower2 );
if ( out_check != out_check_prev )
{
log_printf( &logger, "OUT is: %d\r\n", ( uint16_t ) out_check );
out_check_prev = out_check;
}
}
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
