April | 2013 | Embedded Lab

Monthly Archives: April 2013

Easy Pulse Sensor (Version 1.1) Overview (Part 2)

Posted on April 20, 2013 by R-B 30 comments

In Part 1 of this article, we briefly discussed about the principle of Photoplethysmography (PPG) and its applications in retrieving vital information about the cardiovascular system. The Easy Pulse sensor allows you to measure the pulse rate from fingertip using the transmission mode PPG. The Easy Pulse Version 1.1 uses the HRM-2511-E sensor that fits comfortably onto fingertip. Inside the sensor there is an IR LED that illuminates the finger from one side. A photodetector placed on the opposite side and facing towards the IR LED detects the transmitted light through the finger. The little variations in the transmitted light

Easy Pulse Sensor (Version 1.1) Overview (Part 1)

Posted on April 20, 2013 by R-B 79 comments

The Easy Pulse sensor is designed for hobby and educational applications to illustrate the principle of photoplethysmography (PPG) as a non-invasive optical technique for detecting cardio-vascular pulse wave from a fingertip. It uses an infrared light source to illuminate the finger on one side, and a photodetector placed on the other side measures the small variations in the transmitted light intensity. The variations in the photodetector signal are related to changes in blood volume inside the tissue. The signal is filtered and amplified to obtain a nice and clean PPG waveform, which is synchronous with the heart beat. The original version

MAX7219-based double row 4-digit seven segment LED display

Posted on April 13, 2013 by R-B 6 comments

This display board (SPI7SEGDISP8.56-2R) features eight 7-segment displays arranged in two rows of four digits. The on-board MAX7219 driver enables you to control all LED segments through only 3 I/O pins of microcontroller. The major advantage of using this board is the time-division multiplexing operations required for continuous refreshing of the display digits are performed by the MAX7219 chip, thereby keeping the microcontroller free for doing other pressing tasks. The double row arrangement is suitable for many projects where two variable values are to be displayed simultaneously, such as displaying temperature and humidity, or current and voltage, etc.

MCP9802 temperature sensor and Arduino

Posted on April 12, 2013 by R-B Leave a comment

MCP9802 is a digital temperature sensor from Microchip that measures temperatures between -55°C and +125°C to a digital word. It provides an accuracy of ±1°C (maximum) from -10°C to +85°C. The MCP9802 sensor comes with user-programmable registers that provide flexibility for temperature sensing applications. The register settings also allow user-selectable 9-bit to 12-bit temperature measurement resolution. This sensor has an industry standard 2-wire I2C compatible serial interface, allowing up to eight devices to be controlled in a single serial bus. In this blog post I am going to write about an Arduino sketch to interface the MCP9802 sensor with an

Digital timer relay using PIC18F4620

Posted on April 12, 2013 by R-B One comment

Mark Weir from Australia sent us his revision of our Programmable digital timer switch project. He modified the original code, which was written for PIC16F628A, to incorporate it with PIC18F4620 microcontroller, while hardware and overall functionality remain the same. Here is a link to download his modified version of the firmware written in MikroC compiler. Download Firmware

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