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Showing posts from December, 2013

Capacitive Touch Sensing using a Coin & ARM Cortex M4

Couple of years ago, I bought a Capsense add-on from Texas Instruments for MSP-430 Launchpad. It worked right out of the box as expected but a closer observation showed me that the board was nothing but a colored copper plate PCB with catchy SMD LEDS beneath. Curiosity drove me to internet and books which taught me the concept of Capacitive touch sensing. Armed with the following tools, I set myself to make my own capacitive sensor circuit. Components Used: Stellaris LM4F120XL ARM Cortex M4F board Resistors - 2 x 2.2 M ohm Wires + Conductive surface ( I used a Coin) PROJECT:  The aim to design a simple capacitive touch sensing circuit and code an ARM cortex microcontroller to sense the capacitance change when a human touches the sensor. STELLARIS LM4F120XL:  The Stellaris launchpad from Texas Instruments is the main processing core of the project.  The following are its features ARM - Cortex M4F core ( Floating point) 256 KB Flash and 32 KB Flash, 2KB EEP

Raspberry Pi based Monochrome Video Playback in Nokia 2760 caller ID LCD

Previously, I was successful in interfacing a   Nokia caller ID LCD using MSP430 microcontroller. This time I wanted to drive it using the $35 single board computer - Raspberry Pi to display vital information like CPU temperature, IP address or any notifications. This idea then turned into something fun and better. I thought why not we try to play a simple video on the LCD driven by Raspberry Pi? Components used : Raspberry- Pi  - ARM 11 Soc based Single board comp @700MHz. Nokia 2760 Caller ID LCD Hirose connector for LCD Connecting Wires  PROJECT: The first step is to display a static image on the LCD. I ported the code which I wrote for MSP430 microcontroller to Raspberry Pi in python language. The code worked well displaying a monochrome image on LCD. However, the display rate is not at all satisfactory. This was no surprise to me since python was very slow in execution and GPIO driving. Then I went back to good old C++ and ported the code and tried sending the