R-B | Embedded Lab

Author Archives: R-B

Web-controlled AC outlets

Posted on November 8, 2013 by R-B Leave a comment

This Instructable describes the hardware hacking of Stainley’s remote controlled power outlet and modifying it to make it controllable through web or smartphone using Electric Imp. The Electric Imp is a WiFi enabled development platform powered by a Cortex-M3 processor core enclosed inside a tiny package that looks like a SD card.

Electric Imp controlled power outlets

The Electric Imp is the core of the system operation. When the button on the Web App is activated, an AJAX HTTP Request is made to a URL specific to your Imp. This request is sent to the Imp Agent in the Electric Imp cloud that is specifically associated with your Electric Imp. The Agent code is a mini Web Server that parses the request and if valid, passes it on to your Imp firmware via the cloud. This behind the scenes communication between the server based Agent and the hardware based firmware was developed by the talented people over at Electric Imp. Read More

Rapid Development Board for PIC12F Series Microcontrollers

Posted on November 5, 2013 by R-B 2 comments

The 12F series of PIC microcontrollers are handy little 8-pin devices designed for small embedded applications that do not require too many I/O resources, and where small size is advantageous. These applications include a wide range of everyday products such as hair dryers, electric toothbrushes, rice cookers, vacuum cleaners, coffee makers, and blenders. Despite their small size, the PIC12F series microcontrollers offer many advanced features including wide operating voltage, internal programmable oscillator, 4 channels of 10-bit ADC, on-board EEPROM memory, on-chip voltage reference, multiple communication peripherals (UART, SPI, and I2C), PWM, and more. Today we are introducing a new development board (rapidPIC-08 V1.0) for easy and rapid prototyping of standalone applications using PIC12F microcontrollers.

Rapid PIC12F Series Microcontroller Development Board

Yet another voltage monitor for car’s battery

Posted on October 31, 2013 by R-B Leave a comment

A couple of years ago I built a digital voltage monitor system for my car’s battery and its charging system. It plugs into the car’s cigarette lighter receptacle and displays the instantaneous output voltage across the battery terminals on a 4-digit seven segment LED display. I used Microchip’s PIC16F1827 microcontroller and it’s built-in Fixed Reference Voltage (FVR) module to achieve better A/D conversion accuracy while measuring the battery voltage. Here’s an instructable on building a similar device but using ATtiny13 microcontroller. Instead of displaying real battery voltage, however, this project uses three LEDs as visual indication of battery condition.

Car’s battery voltage monitor

Solar-powered outdoor weather station with PC logging and graphs

Posted on October 29, 2013 by R-B 2 comments

I have always enjoyed reading/doing projects that involve sensing various environmental parameters and recording them. This Solar-powered outdoor weather station built upon the Arduino platform measures the ambient temperature, humidity and barometric pressure, and send these parameters to a PC using XBee RF modules. The measurements are recorded on the PC and presented in nice charts showing their temporal trends.

Solar-powered weather station

The beauty of this project is that the outdoor module is fully powered through a Lipo battery which is charged through a solar panel. Sensors used in this project are DHT22 for temperature and relative humidity measurements, and BMP0805 for measuring barometric pressure.

Bi-color LED matrix display board with Bluetooth

Posted on October 29, 2013 by R-B 4 comments

I shared the details of my single-color 8X40 LED matrix display board project here a few months ago. Here is a nice instructable on making a 7 Bi-color 8×8 LED Matrix Scrolling Text Display with Bluetooth support; which means you can send messages and commands to the display via Bluetooth using a Smart Phone. The author illustrates using an Android-based phone, but any devices capable of sending text messages via Bluetooth would work.

Bi-color LED matrix with Bluetooth support

The project uses 7 Bi-color 8×8 LED matrices, each controlled by two MAX7219 chips. The beauty of using MAX7219 is they take a lot of work off the micro-controller and simplify the design. Moreover, they can be daisy chained and require only three output pins on the micro-controller for the required SPI-interface. The project is constructed using the Arduino embedded platform. In order to achieve faster speed and better scrolling effect, the author used the chipKit Uno32 board instead of the original Arduino Uno board. A HC-07 Bluetooth module is used for wireless serial communications between the display and the Android Smart Phone.

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