HEF4755VPN データシートの表示（PDF） - Philips Electronics

部品番号

コンポーネント説明

メーカー

HEF4755VPN

Transceiver for serial data communication

Philips Electronics 

Philips Semiconductors

Transceiver for serial data communication

Product specification

HEF4755V

LSI

FUNCTIONAL DESCRIPTION

General

The HEF4755V is used for protected-bit serial data

communication. This protection makes it necessary to

subdivide the serial data stream into data blocks called

messages.

Messages

In the synchronous mode the HEF4755V will transmit or

receive a message as follows:

The first bit of a transmitted message is the start-bit which

cannot be mis interpreted. It instructs the receiver, that

information transfer has started and it defines the

time-window for the following bits. The start-bit is only

necessary in the asynchronous mode and it is omitted in

the synchronous mode. The first byte contains the number

of data bytes that will follow. This byte is checked by the

receiver and if a discrepancy is found, the receiver reports

a code-error. This first byte is called ‘size’. The number of

data bytes can also be fixed by wiring of the transmitter as

well as the receiver. In this case the size byte is omitted.

There is no protocol on the information of the data bytes,

so the maximum number of informations per message is

256 ≈ 1017.

The redundancy check byte secures the data bytes

against transmission errors. This byte is calculated in

parallel to the data stream and it is send as last byte by the

transmitter. The receiver calculates its own redundancy

byte and compares it with the received one. If there is a

discrepancy, the receiver reports a code error.

Code protection

Size

The coding of the size byte is as follows:

DIO0 = C

DIO1 = B

n = C ⋅ 22 + B ⋅ 21 + A ⋅ 20

DIO2 = A

DIO3 = P

= C⊕B⊕A

The information is transmitted as follows:

With this, a hamming distance of 4 is obtained.

January 1995

6

Share Link: