Common Emitter: May 2012

2012-05-23

Free USB PID for open source projects

As the openmoko products have been discontinued, Openmoko Inc. is opening up the use of its Vendor ID for use by the Free and Open Source software and hardware communities. Open Source developers can register their devices to allocate Product ID (PID) for free. Details: http://wiki.openmoko.org/wiki/USB_Product_IDs.
MAC address (or address range) can be obtained in a similar way: http://wiki.openmoko.org/wiki/OUI#Conditions.
See also: http://laforge.gnumonks.org/weblog/2012/05/21/#20120521-open_registry_for_usb_and_mac_addrs.

2012-05-16

Fixing Philips SA2620/SA2640 mp3 players

Recently I've bought huge pack of damaged and incomplete mp3 players - mostly as a cheap parts source hoping to find few TEA5767 FM radio modules inside.

Most of these devices are not worth fixing nowadays (1 GB or less FLASH memory and/or severe mechanical damages) there were few Philips SA2620 (2 GB) and SA2640 (4 GB) players that were very easy to repair.

After connecting to PC they were recognized either as Mass Storage Device with VID 0471, PID 2030 (most of them) that failed to initialize with error code 10 or as HID device, VID 066F (SigmaTel), PID 3700 (AFAIR only one of the eight pieces).

To fix this problem download Philips Device Manager - software used to restore or upgrade player firmware. Install & run. If mp3 player was not enumerated as HID device connect it to USB port while pressing "backspace" button (at the top of the player), it would be enumerated as HID then and Philips software would detect it and offer fixing it. After 1 minute device firmware would be restored.

Note that all previous FLASH memory content would be erased.

2012-05-14

Dave Jones on a PC oscilloscopes

Here are two Dave Jones videos on a PC oscilloscopes.

EEVblog #13 Part 2 of 2 - Comparison of PC Based Oscilloscopes

EEVblog #86 - Buy a real Analog Oscilloscope PLEASE!

Although I partially disagree with these opinions - some PC oscilloscopes have no match when working as a fast data loggers and ability to capture continuous stream is very useful to me - there is a lot of truth in them. That said, beware of cheap USB oscilloscopes that are just overpriced sound cards in disguise like this one:

As you can see even sound card type used is not consistent.

Warning signs are:

two oscilloscope + two generator channels,
high-resolution (16 or 24 bit) ADC advertised,
sampling frequency 48, 96 or 192 k,
no drivers needed.

2012-05-06

AVR pinout stickers

These AVR stickers would save some time counting pins and referring to datasheet when using microcontrollers on breadboard.
Original idea comes from http://diy4fun.blogspot.com/2010/02/atmega-1632-pinout-sticker.html and it included stickers for ATmega16 and ATmega32. Stickers for other popular AVRs (ATmega8/48/88/168, ATtiny26 and ATtiny2313) can be found at http://avrproject.ru/publ/instrument/stikery_dlja_mikrokontrollerov_avr/3-1-0-56.

2012-05-04

FM PLL radio with TEA5767 module

TEA5767 module allows to build own PLL FM radio with good sensitivity and separation. This module is popular, cheap ($1.85 at aliexpress, min. 10 pcs, free shipping), can be even extracted from old S1MP3 player (marked with [K], see http://www.s1mp3.org/en/docs_hwspecs.php):

These modules are controlled with I2C or SPI (selectable). They do not require any calibration.

Following pictures presents complete FM radio with '51 MCU and TBA820 audio amplifier built into beautiful wooden speaker. Source: http://as.elte-s.com/zrob/radio_tea5767.htm.

Modules with TEA5767, AVR microcontroller and headphone amplifier (TDA1308, 80 mW max), few pushbuttons, ISP and LCD connector cost about $16.

For AVR (avr-gcc/WinAVR) code check http://tomeko.net/projects/TEA5767_radio/.

2012-05-01

Trolling is a art

It's month after April’s Fool Day and this prank is a year old itself but it still is worth to try. Print, tape to the wall next to printer/copier, enjoy.