Article USB in a NutShell Part 2

Connectors

All devices have an upstream connection to the host and all hosts have a downstream connection to the device. Upstream and downstream connectors are not mechanically interchangeable, thus eliminating illegal loopback connections at hubs such as a downstream port connected to a downstream port. There are commonly two types of connectors, called type A and type B which are shown below.

Type A USB Connector	Type B USB Connector

Article USB in a NutShell Part 1

Making sense of the USB standard

Starting out new with USB can be quite daunting. With the USB 2.0 specification at 650 pages one could easily be put off just by the sheer size of the standard. This is only the beginning of a long list of associated standards for USB. There are USB Class Standards such as the HID Class Specification which details the common operation of devices (keyboards, mice etc) falling under the HID (Human Interface Devices) Class - only another 97 pages. If you are designing a USB Host, then you have three Host Controller Interface Standards to choose from. None of these are detailed in the USB 2.0 Spec.

About of MP3 Player

The Bottom Line Quite a few developments have occurred since I've written my two how to choose an MP3 player and CD-MP3 player essays. Time to reevaluate the market!

MP3 player technology has become cheaper with new products and breakthroughs on the horizon. Time to reevaluate the market and consider whether it's time to wait for the new technology or is it okay to buy now?

What's here now?

Consumer electronics

Consumer electronics are electronic equipment intended for everyday use, most often in entertainment, communications and office productivity. Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver. Later products include personal computers, telephones, MP3 players, audio equipment, televisions, calculators, GPS automotive electronics, digital cameras and players and recorders using video media such as DVDs, VCRs or camcorders. Increasingly these products have become based on digital technologies, and have largely merged with the computer industry in what is increasingly referred to as the consumerization of information technology.

Data Transfer 80C51

Internal RAM
Table 3 shows the menu of instructions that are available for moving data around within the internal memory spaces, and the addressing modes that can be used with each one. With a 12MHz clock, all of these instructions execute in either 1 or 2ms. The MOV [dest], [src] instruction allows data to be transferred between any two internal RAM or SFR locations without going through the Accumulator.

Instruction Set of 80C51

Arithmetic Instructions
The menu of arithmetic instructions is listed in Table 1.4.1 The table indicates the addressing modes that can be used with each instruction to access the operand.
For example, the ADD A, instruction can be written as:

Addressing modes in the 80C51

The addressing modes in the 80C51 instruction set are as follows:
An "addressing mode" refers to how you are addressing a given memory location. In summary, the addressing modes are as follows, with an example of each:

Special Function Register Microcontroller

A Map of the on-chip memory area called the Special Function Register (SFR) space is shown in Figure 1.2.1. Note that in the SFRs not all of the addresses are occupied. Unoccupied addresses are not implemented on the chip. Read accesses to these addresses will in general return random data, and write accesses will have no effect.

Microcontroller MCS-51 Architecture

Memory Organization

All 80C51 devices have separate address spaces for program and data memory, as shown in Figures 1.1.1 and 1.1.2. The logical separation of program and data memory allows the data memory to be accessed by 8-bit addresses, which can be quickly stored and

5-BAND GRAPHIC EQUALISER

By aRie eMDee
This equaliser uses low-cost op-amps. Good-quality opamps powered by a single voltage supply are readily available in the market. The op-amp should have a noise density of less than 24nV/√Hz, slew rate of more than 5V/µs and gainbandwidth product greater than 3MHz. The NE5532 or LM833 used in this circuit meets these requirements. Equaliser circuits typically divide the audio spectrum into separate frequency bands and have independent gain control for each band.