Powering a sustainable future using BQ25570 and PIC18F57Q43

Efficient power, happy planet!

Solar energy click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

Solar energy click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Provide power to your solution using the solar panel and charge the LiPo rechargeable battery efficiently

Hardware Overview

How does it work?

Solar energy Click is based on the BQ25570, a nano-power high-efficiency boost charger, and buck converter from Texas Instruments, designed to work with very low-power energy harvesting elements. It can both provide power to the connected external load and charge the LiPo rechargeable battery using the solar panel as the photovoltaic element - employing its energy harvesting capabilities. The connected load will be powered on from the connected LiPo battery or the supercapacitor soldered on board. When the battery voltage drops under 2.85V, the interrupt pin (routed to the mikroBUS™ INT pin) will be driven to a LOW logic state. The integrated nano-power management unit provides the proper

charging conditions for the battery. When the battery is charged up to 3.25V due to the hysteresis set with the voltage divider resistors, the INT pin will again go to a HIGH logic state. Also, thanks to the nano-power management unit, the battery will not get overcharged above 4.06V. The click board™ provides 2.6V/100mA for the connected external load on the output terminal. The internal supercapacitor will be used as the energy storage element when the battery is not connected. This is useful for continuous powering up of very low-power applications, as the supercapacitor should be able to provide power continuously since it will get recharged by the solar panel before the load drains it out.

The internal converter will be disabled if the storage element voltage drops under the internally set under-voltage level of 1.95V, preventing the damage of completely draining out the connected storage element. In addition to the INT pin, there are two more pins of the BQ25570 routed to the mikroBUS™, used to enable the BQ25570 internal sections (EN) and to enable the power output for the connected load (OUT). Setting the EN pin to the LOW logic level will allow the BQ25570 internal sections and the power charger features, while the HIGH logic level on the OUT pin will enable the power output for the connected load.

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.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

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.

Li-Polymer Battery is the ideal solution for devices that demand a dependable and long-lasting power supply while emphasizing mobility. Its compatibility with mikromedia boards ensures easy integration without additional modifications. With a voltage output of 3.7V, the battery meets the standard requirements of many electronic devices. Additionally, boasting a capacity of 2000mAh, it can store a substantial amount of energy, providing sustained power for extended periods. This feature minimizes the need for frequent recharging or replacement. Overall, the Li-Polymer Battery is a reliable and autonomous power source, ideally suited for devices requiring a stable and enduring energy solution. You can find a more extensive choice of Li-Polymer batteries in our offer.

Solar Panel offers an efficient alternative powering solution for your device, harnessing the remarkable photoelectric effect to generate electricity when exposed to sunlight. Comprising monocrystalline silicon solar cells encapsulated with PC film lamination, this panel ensures durability and protection from environmental elements. The magic lies in the photoelectric effect, where sunlight excites electrons in the silicon cells, creating an electric current. The panel's construction optimizes sunlight absorption and conversion, enabling it to generate a minimum output of 4.0V. It can produce electrical power under a maximum load of 100mA, making it ideal for various applications. This solar panel offers a sustainable and eco-friendly approach, providing a renewable energy source that reduces reliance on conventional power grids and promotes environmental consciousness.

Used MCU Pins

mikroBUS™ mapper

Buck Enable

PA0

RST

Chip Enable

PD4

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

Battery OK Indication

PA6

INT

SCL

SDA

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Charger 27 Click front image hardware assembly

PIC18F47Q10 Curiosity Nano front image hardware assembly

Charger 27 Click complete accessories setup image hardware assembly

Curiosity Nano with PICXXX Access MB 1 - upright/background hardware assembly

PIC18F57Q43 Curiosity MCU Step hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

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 Solar energy Click driver.

Key functions:

solarenergy_charge_enable - Charge enable function
solarenergy_charge_disable - Charge disable functions
solarenergy_check_indicator - Battery good indicator functions

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 
 * \brief SOLAR ENERGY Click example
 * 
 * # Description
 * This application charge the batery when is empty.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enables - GPIO and start to write log.
 * 
 * ## Application Task  
 * This is an example which demonstrates the use of Solar Energy Click board.
 * The following example will charge the battery if it is empty, and stop charging
 * when the battery is full. When battery full status is detected, the device is
 * disabled, but will check battery status every 10 seconds.
 * Results are being sent to the Usart Terminal where you can track their changes.
 *
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "solarenergy.h"

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

static solarenergy_t solarenergy;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;
    solarenergy_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.

    solarenergy_cfg_setup( &cfg );
    SOLARENERGY_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    solarenergy_init( &solarenergy, &cfg );

    log_printf( &logger, "   Initialization   \r\n" );
    log_printf( &logger, "--------------------\r\n" );
    log_printf( &logger, " Charge the battery \r\n" );
    log_printf( &logger, "--------------------\r\n" );
    Delay_ms ( 1000 );
}

void application_task ( void )
{
    if ( solarenergy_check_indicator( &solarenergy ) )
    {
        solarenergy_charge_disable( &solarenergy );
        // 10 seconds delay
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
        Delay_ms ( 1000 );
    }
    else
    {
        solarenergy_charge_enable( &solarenergy );
    }
}

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