Saturday, December 22, 2018

BMP180 based USB atmospheric pressure monitor

We initially developed this USB atmospheric pressure monitor to study some operating characteristics of Bosch BMP180 sensor. BMP180 is low cost sensor to measuring barometric pressure and temperature. According to the data sheet this sensor can use to measure pressure ranging between 300hPa to 1100hPa. This sensor is introduced couple of years back but still it is popular due to lower cost and simplicity of it's interface.

BMP180 based sensor module

We did this unit to test BMP180 sensor more accurately and to study it’s behaviors. This unit is based on PIC18F2550 microcontroller and the main reason to select this MCU is because of it’s built-in USB 2.0 interface.

BMP180 sensor monitor application

To display sensor calibration data and it’s readings we did small windows application. This application display and plot temperature and pressure readings captured from the BMP180 sensor.

This unit is programmed to work as a USB HID device and no any special device driver is required to use this device. We test this unit in Windows 10 environment.

All the schematics, firmware files and source codes of this project are available at https://github.com/dilshan/bmp180-monitor.

Sunday, December 9, 2018

RTC based automatic LED lamp

This is real-time clock based automatic LED lamp which we originally designed to use as night light. This lamp can programmed to turn on and off at the specific time of the day. For example, it can program to turn on at 6 PM on each day and to turn off at 4 AM next day.

The core component of this project is PIC16F883 MCU and it's firmware is developed using MikroC Pro for PIC. We select this MCU because of it's 7 KB flash memory, I2C, UART, E2PROM and built-in 8-bit and 16-bit timers. In this system we use DS1307 RTC because of it's availability in the market and lower external component count.

Prototype version of RTC Lamp

This lamp is designed to work with commonly available 7W LED panels. In our prototype design we use 7W 24V warm-white LED module to test this system. To drive other LED modules change value of the R5 resistor of the current limiter circuit.

This system is designed to program using RS232 serial port. User can modify system time, light start and end times by connecting this system to any computer through RS232 serial port. To program and view system information user can use any serial terminal application like minicom, putty, etc.