Archive for April, 2007
« Previous EntriesUSB - Signaling
Sunday, April 29th, 2007USB Signaling:
Pin numbers (looking as a socket):
Pin assignments
Pin
Function
1
Vbus (4.75 - 5.25 V)
2
[…]
USB - Packet Format
Sunday, April 29th, 2007USB packets have a format very similar to the packets used on the very early internet. It is nearly impossible to clearly understand USB connectivity without understanding the structure of the USB packet.
USB Packet Format:
OFFSET
TYPE
SIZE
[…]
USB - Transfer Speeds
Saturday, April 28th, 2007USB supports three data rates.
A Low Speed rate of 1.5 Mbit/s (183 KiB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks.
A Full Speed rate of 12 Mbit/s (1.5 MiB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. […]
USB - Error Handling
Saturday, April 28th, 2007Considerable error checking and error handling features have been built in to the USB to ensure that it is a reliable method of connecting peripherals to a PC. Data integrity should be comparable to that of an internal expansion bus.
Immunity from data corruption by noise and spikes has been provided by the use of differential […]
USB - Bus Protocol
Friday, April 27th, 2007Information transfers over the bus are called transactions. At any time the host controller may have a list of transactions that are waiting to be actioned. A transaction begins when the controller sends a packet describing the type and direction of the transaction, the 7-bit USB device address and the endpoint number. This packet is […]
What Is Flash Memory
Friday, April 27th, 2007Flash memory is a form of non-volatile computer memory that can be electrically erased and reprogrammed. Unlike EEPROM, it is erased and programmed in blocks consisting of multiple locations (in early flash the entire chip had to be erased at once). Flash memory costs far less than EEPROM and therefore has become the dominant technology […]
The Basic Difference Of Flash Memory
Thursday, April 26th, 2007Flash memory refers to a particular type of EEPROM, or Electronically Erasable Programmable Read Only Memory. It is a memory chip that maintains stored information without requiring a power source. Flash memory differs from EEPROM in that EEPROM erases its content one byte at a time. This makes it slow to update. Flash memory can erase […]
USB - Communication
Thursday, April 26th, 2007Although a physical map of a USB may look like a tree, logically the bus appears as a star with up to 127 devices connected to a single hub. Client software communicates directly with its device. Each device has a unique address, which is assigned to it by the USB system software during configuration to […]
USB - Topology
Thursday, April 26th, 2007USB connects several devices to a host controller through a chain of hubs. In USB terminology devices are referred to as functions, because in theory what we know as a device may actually host several functions, such as a router that is a Secure Digital Card reader at the same time. The hubs are special […]
Encoding and Streaming to your Pocket PC (3)
Wednesday, April 25th, 2007Encoding and Streaming to your Pocket PC
(continuation)
Figure 4: Encoder 9 encoding away
Encoder 9 does the video encoding in two passes. During the first pass, there isn’t any output displayed.
In either case, once the encoding has finished, copy the “wmv” file onto your Pocket PC, start up Windows Media Player, click on Select, click on your […]