logIt Log Around The Clock

Archive for March 2013

Duplicate/Restore ARM Linux Image to MMC/SD Card (BeagleBoard and DevKit ARM)

By booting from MMC/SD card, you can bring up your BeagleBoard-xM or DevKit8500D (both are ARMv7). It is the only way for the xM (microSD card to be exact), while with DevKit, you have the option to flash it to the board for NAND-boot once you’re sure that it works with SD card. eLinux wiki [...]

Modem usb_modeswitch in Raspberry Pi

USB modem these days are plug-and-play as CD-ROM first allowing driver and internet dialer application installations and then as modem afterwards. This Windows-behavior is handled by USB_ModeSwitch in Linux. Likely three years ago we did eject and other driver attachment by writing udev rules. Now it’s almost automatically attached as modem after insertion and people [...]

Raspberry Pi Common USB Problems

USB problem is the first thing to arise with Raspberry Pi when plugging-in peripherals. This isn’t exclusive though, learning that my Linux laptop also has it and the higher ARM architecture, BeagleBoard-xM, also experiences the same issue sometime. But with Raspberry Pi (RPi) in

Raspberry Pi: Membrane (Matrix) Keypad as GPIO Input

Membrane matrix keypad using GPIO as Raspberry Pi input has been my goal since WiringPi deployed in the first place. To begin with, GPIO hacking was initially started with some important basics (see previous post). Without external system (other interfacing chip), the 3×4 membrane keypad reserved all seven GPIO pins plus one pin used for [...]

Raspberry Pi GPIO Input Button Basics

When you start hacking Raspberry Pi’s GPIO, first thing to keep in mind is the +3.3V CMOS logic level voltage despite the 5V supply. Secondly, read references about current limiting resistors (eLinux Wiki has a section there). What to avoid then? Try not to physically short the GPIO pin to ground when it is programmed [...]