Mar 24
USBtoparallel
This device was built using AVRUSB firmware developed by extern Objective Development.
Meanwhile, a very similar Release 1.6 exists.
This Low-Speed device violates following USB specification rules:
* Detachable cable (must be captive for Low-Speed)
* Output drivers with 5 V (must be 3.3 V, but USB is 5 V tolerant)
* No differential data input (only one line D- is sampled)
* No data clock regenration while receiving (only at packet start)
* No error detection of input data (OUT direction), no time for CRC16
* Data transfer using BULK pipes (not specified for low-speed, but works on Windows – for Linux there is an “Alternate Setting” with INTERRUPT pipes instead)
However, new to this firmware, following rules are accepted:
* Suspend detection and lowered suspend current (below 500 µA)
[Via]
Mar 23
The Universal Serial Bus (USB) interface has become extremely popular, due to its simplicity for end user applications (Plug and Play without restart). For developers, however, USB implementation into end systems has been more complicated compared to e.g. RS232. In addition there is a need for device drivers as software support on the PC side. Because of this, RS232 based communication is still very popular among end systems manufacturers. This interface is well established and has good operating system support, but recently the physical RS232 port has been removed from the standard PC interface, giving ground to USB ports. Implementation of USB into external devices can be done in two ways:
1. By using a microcontroller with hardware implemented USB interface. It is necessary to know how USB works and write firmware into the microcontroller accordingly. Additionally, it is necessary to create a driver on the computer side, unless if the operating system includes standard USB classes. The main disadvantage is the lack of availability of this kind of microcontrollers and their high price compared to simple “RS232” microcontrollers.
Read the rest of this entry »
Dec 25
usb battery Charger
usb Battery charger schematic
The charger in this project is designed to charge two AA NiMH or NiCd cells of any capacity (as long as they are the same) at about 470mA. It will charge 700mAh NiCds in about 1.5 hours, 1500mAh NiMHs in about 3.5 hours, and 2500mAh NiMHs in about 5.5 hours. The charger incorporates an automatic charge cut-off circuit based on cell temperature, and the cells can be left in the charger indefinitely after cut-off. Read the rest of this entry »
Dec 25
Usb Sound card
Make a sound card is no more a complex issue. If you use great IC PCM2702 from BURR BROWN / Texas Instruments you can create a fully functional USB sound card. This sound card can be powered from USB port and has one stereo output. You don’t need to install any driver for Windows XP and Vista, because they are already inside. This is really plug and play. Read the rest of this entry »
