Achieve ultimate control and comfort with BPS230 and PIC18LF2515

Keep humidity and temperature in check for ultimate balance

Published Nov 01, 2023

Click board™

Temp&Hum 10 Click

Dev Board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18LF2515

From homes to industrial facilities, our solutions adapt to diverse settings, providing crucial data for maintaining optimal conditions in any space.

Hardware Overview

How does it work?

Temp&Hum 10 Click is based on the BPS230, a relative humidity and temperature sensor with I2C interface from Bourns. This sensor IC integrates two very accurate sensing components: temperature sensor, and relative humidity sensor. By utilizing the proprietary manufacturing technology, this sensor integrates the complete temperature and humidity measurement system on chip. The output data is processed and compensated by the BPS230 sensor IC itself, requiring only basic conversion formulas to be applied within the firmware of the host microcontroller (MCU). These conversion formulas are given in the BPS230 datasheet and provide readings in °C and %RH, directly. The BPS230 incorporates an accurate bandgap temperature sensor, which can measure the temperature in the range between -30 °C and 100 °C while retaining accuracy of ±0.4°C, typically. The accuracy is even greater if the range is narrowed down: when used over the range between -10°C and 70°C, the typical accuracy is ±0.1 °C. Also, the reproducibility of the temperature measurement is very good, in the range of 0.1°C. The BPS230 sensor IC can be reliably used for prolonged periods of time.
After the measurement has been converted by a high-precision ADC, it is fed to a logic back-end which applies

factory-calibrated correction and converts the raw data into a compensated value. By applying a simple conversion formula, the measurement can be easily converted in °C. The raw temperature measurement value is in the 11-bit format. Please note that the sensor will take some time to accommodate to the ambient temperature, especially if the temperature changes quickly, considering the thermal conductivity of the PCB itself. The response time of both sensors is also affected by the averaging ratio, which can be configured over the I2C interface. The humidity sensor is a capacitor type polymer-based sensor which changes the capacitance proportionally to the relative humidity. However, the capacitance of this sensor is affected by changes of the ambient temperature, as well. The accuracy of the RH sensor varies in the range between ±3% and ±5%, depending on the measurement conditions (ambient temperature). After the measurement has been converted by a high-precision ADC, it is fed to the logic back-end which applies factory-calibrated correction and converts the raw data into a compensated value. By applying a simple conversion formula, the measurement can be easily converted in %RH. The raw RH measurement value is in the 10-bit format. Please note

that capacitor-based humidity sensors commonly suffer from a small hysteresis, which may occur if the sensor is used in very humid conditions for prolonged periods of time. However, this hysteresis is not irreversible. The BPS230 datasheet specifies that its hysteresis should stay within the range of ±1 %RH. The CS pin of the mikroBUS™ is routed to the CE pin of the BPS230 sensor IC. This pin is used to set the operating mode of the sensor by the host MCU either in Sleep or StandBy mode. When there is a LOW logic level on the CS pin, the device operates in Sleep mode. While in Sleep mode, the power consumption is reduced to a minimum: the internal clock of the IC is stopped, and the I2C interface is disabled. By applying a HIGH logic level to this pin, the IC enters the StandBy mode, with the I2C interface enabled. Temp&Hum 10 click uses the I2C communication interface. It has pull-up resistors connected to a selectable voltage source. A small SMD jumper can be used to switch between 3.3V and 5V. This jumper switches the voltage for both the IC and two pull-up resistors, allowing the Click board™ to be used with a wide range of MCUs, both using 3.3V and 5V.

Temp&Hum 10 Click hardware overview 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.

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

3968

Used MCU Pins

mikroBUS™ mapper

RST

Chip Enable

RA5

SCK

MISO

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

I2C Clock

RC3

SCL

I2C Data

RC4

SDA

Power Supply

Ground

GND

Take a closer look

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.

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.

Rotary B 2 Click front image hardware assembly

EasyPIC v7 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 Temp&Hum 10 Click driver.

Key functions:

temphum10_get_temperature - Functions for read Temperature data
temphum10_set_device_mode - Functions for sets Device mode
temphum10_repeat_measurement - Functions for repeat measurement

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 TempHum10 Click example
 * 
 * # Description
 * This application measures temperature and humidity.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver init and sets device mode
 * 
 * ## Application Task  
 * Reads Temperature and Humidity data and logs this data to USBUART every 1 sec.
 * 
 *  ## NOTE
 * If you are expiriencing issues with comunication, please try another mikroBUS socket or set the VCC SEL jumper at 5V.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "temphum10.h"

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

static temphum10_t temphum10;
static log_t logger;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    temphum10_cfg_t cfg;
    uint8_t tmp;

    /** 
     * 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.

    temphum10_cfg_setup( &cfg );
    TEMPHUM10_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    temphum10_init( &temphum10, &cfg );

    log_info( &logger, "---- Device config ----" );
    
    temphum10_set_device_mode( &temphum10, TEMPHUM10_MODE_STANDBY );
    Delay_ms( 100 );
    
    tmp = TEMPHUM10_RST_NORMAL_OPERATION;
    temphum10_generic_write( &temphum10, TEMPHUM10_REG_DEVICE_RESET, &tmp, 1 );
    Delay_ms( 100 );
    log_info( &logger, "---- Device calibration ----" );
    tmp = TEMPHUM10_AM_TIMES_AVERAGE_MODE_8 | TEMPHUM10_AM_TEMP_AVERAGE_MODE_TIMES_16;
    temphum10_repeat_measurement( &temphum10, tmp );
    temphum10_get_temperature( &temphum10 );
    temphum10_get_humidity( &temphum10 );
    Delay_ms( 100 );
    temphum10_repeat_measurement( &temphum10, tmp );
    temphum10_get_temperature( &temphum10 );
    temphum10_get_humidity( &temphum10 );
    log_info( &logger, "---- Application Task ----" );
}

void application_task ( )
{
    float temperature = 0;
    float humidity = 0;
    uint8_t tmp;
    
    tmp = TEMPHUM10_AM_TIMES_AVERAGE_MODE_8 | TEMPHUM10_AM_TEMP_AVERAGE_MODE_TIMES_16;
    temphum10_repeat_measurement( &temphum10, tmp );
    temperature = temphum10_get_temperature( &temphum10 );
    humidity = temphum10_get_humidity( &temphum10 );
    
    log_printf( &logger, " Temperature : %.2f \r\n", temperature );
    log_printf( &logger, " Humidity :  %.2f \r\n", humidity );
    log_printf( &logger, "---------------------\r\n" );

    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

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

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