MP3 Download Box - Download Unlimited MP3 Legally. As low as $1/month
Spyware Doctor with AntiVirus - Easy Spyware Removal - FREE SCAN
About Analog to Digital Conversion (ADC)
Supported by A/D chip or internal A/D converter.
Characterized by:
1. Resolution – the minimum change in input voltage that can give rise to a change in output
Resolution = (VRH – VRL) / (# of quantization steps) # of quantization steps = 2^b where b is # bits used for encoding
2. Linearity – higher for a better conversion
3. Speed
Need data rate to satisfy the Nyquist criterion.
Recall that Nyquist criterion says sampling frequency should be at least twice the frequency of the fastest harmonic of the signal to be sampled.
Popularity: 6%
About Seven Segment LED
A seven segment LED consist of seven light emitting diode segments and one segment for the decimal point. The segments are physically arranged in the form of 8.
To display a number , or a letter from A to F the necessary segments are lit by sending an appropriate signal for current flow through the diodes.
An LED will be illuminated if it is forward-biased and there is enough current flowing through it.
Typically, a current of few milliamps up to 20mA is required.
The voltage drop across a forward-biased LED ranges from about 1.6V to 2.5V.
The 7 segment LEDs are available in two types:
i) common cathode
ii) common anode.
The current flow in these diodes should be limited to 20 ma. The segments A through G are are usually connected to data lines D0 through D6 respectively. If the decimal point is used the data line D7 is connected to the decimal point, otherwise it is left open.
The binary code required to to display a digit is determined by the type of LED configuration ( common anode or common cathode)
For common anode configuration a logic 0 is required to turn on a segment. For common cathode type a logic 1 is required.
With displays having many display elements, rather than having to use a decoder for each element, multiplexing is used with a single decoder.
To maintain a constant display, a display is repeatedly turned on sufficiently often for the display to appear flicker-free.
Popularity: 7%
Parallel communication - Review
Multiple data, control, and possibly power wires
One bit per wire
High data throughput with short distances
Typically used when connecting devices on same IC or same circuit board
Bus must be kept short
long parallel wires result in high capacitance values which requires more time to charge/discharge
Data misalignment between wires increases as length increases
Higher cost, bulky
Popularity: 6%
Serial Communication - Review
Single data wire, possibly also control and power wires
Words transmitted one bit at a time
Higher data throughput with long distances
Less average capacitance, so more bits per unit of time
Cheaper, less bulky
More complex interfacing logic and communication protocol
Sender needs to decompose word into bits
Receiver needs to recompose bits into word
Control signals often sent on same wire as data increasing protocol complexity
Popularity: 6%
I/O Devices
Peripheral devices (also called I/O devices) are pieces of equipment that exchange data with a CPU
Examples: switches, LED, CRT, printers, keyboard, keypad
Speed and characteristics of these devices are very different from that of CPU so they cannot be connected directly
Interface chips are needed to resolve this problem
Main function of an interface chip is to synchronize data transfer between CPU and I/O device
Data pins of interface chip are connected to CPU data bus and I/O port pins are connected to I/O device
Since a CPU may have multiple I/O devices, CPU data bus may be connected to data buses of multiple interface
An address decoder is used to select one device to respond to the CPU I/O request
Different CPUs deal with I/O devices differently
Some CPUs have dedicated instructions for performing input and output operations (isolated I/O)
Other CPUs use the same instruction for reading from memory and reading from input devices, as well as writing data into memory and writing data into output devices (memory-mapped I/O)
8051 is memory mapped
Popularity: 6%
Fet89c5x Programmer Download - Best 8051 compiler
Best 8051 compiler software to use. Works with all kinds of 8051 microcontroller.
Compile 8051 asm to hex.
Popularity: 11%
