Computing systems 1 (data transmission)

directions of data transmission (3)

simplex: one direction. sending or receiving data from a device

DATA ONLY GOES ONE WAY

duplex: sending data to and from devices

(BOTH DIRECTIONS, BUT ONLY ONE AT A TIME)

full duplex: BOTH DIRECTIONS AT THE SAME TIME

define interface

pawtcsc

a point at which two computer systems communicate

what is a serial interface

an interface that allows serial communication between a microcontroller to a microcontroller/processor using a SERIAL cable

(one wire to transmit, one to receive)

define serial communcation

the process of sending data one bit at a time, sequentially, over a single communication channel

what is SYNCHRONISED communication

each bit is synchronised to the oscillations of an on board clock

(continuous stream of data)

steps for synchronised serial communication:

1. _____ counts how many bits were sent and __________ the bits into bytes

2. timing signals are sent ______ the data

3. _____ (speed?) as only data bits are sent (so used when ______ is important e.g. network connections)

1. receiver counts how many bits were sent and reassembles the bits into bytes

2. timing signals are sent WITH the data

3. FAST as only data bits are sent (so used when speed is important e.g. network connections)

asynchronous serial communication: how is data packaged

how are they sent across

sent as a packet

files are broken up into many packets and reassembled at the receiving endd

what is the format of a packet

a frame:

contains all info required to interpret data at the receiving end

what do communicating devices agree on their protocol before transmission:

bit pattern and bit rate (bit’s per second)

what does this mean for speed

slightly slower than synchronous

what does usb stand for

universal serial bus

advantages of USB and USB-C (3, 3)

disadvantages (2)

• fits/works both ways

• can run basically any modern protocol

• more power than older USB

• lots of compatibility

• very fast data transmission

• automatically detects if the correct driver is installed

• max cable length only 5 metres

• older standard becoming obsolete

why is serial transmission reliable

• bits stay in the correct order, less skewed/unsynchronised data as only 1 wire is used

define parallel communication

several bits are sent at the same time, on a link with several channels in parallel with each other

serial vs parallel (2)

• parallel faster than serial

• but parallel is not reliable over long distances, so mainly found on very short communication channels of printed circuit boards (where channels are fixed in positions and synchronisation is likely to be undisturbed)

  • there may be signal degradation, timing issues so data is wrongly aligned, etc.

what provides the timing for parallel

• oscillations of the system clock

define port, hardware, software

hardware: connection point/interface between a computer and an external or internal hardware device

software: a virtual point where network connections start and end

define protocols

set of rules for communication between devices

what is the baud rate

how fast data is sent over a serial line

(if it goes too high you might get errors)

what is parity checking

basic principle: something to do with the bits being total even or odd idk

used in data transmission to check for errors: if parity is incorrect, an error is detected

what is the time to live variable/what does it do?

TTL (Time To Live) is a value that limits how long a piece of data should exist or be considered valid. It's commonly used in networking to prevent packets from circulating indefinitely and in caching to determine when data should expire.