TEA6414A Просмотр технического описания (PDF) - STMicroelectronics

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TEA6414A

BUS-CONTROLLED VIDEO MATRIX SWITCH

STMicroelectronics 

TEA6414A

µP

IC

IC

IC

IC

1

2

3

n

The identification or address of each particular IC

is achieved by the length of the word (number of

clock pulses), and each IC responds with its own

particular word length. The address length is deter-

mined only while ENABLE is low, by counting the

clock pulses. The rising edge of the ENABLE signal

indicates the end of the address sequence.

Normally, there are several locations within the

same chip, which must be selected individually, the

datastream may, therefore be split into subaddress

and data. In the case where an IC is not using the

complete specified subaddress range it is possible

to employ the unused subaddress range with a

second or third IC with the same word length. The

bitnumber of the subaddress is flexible.

The reply word length from any of the ICs to the µP

is also flexible. This bidirectional transmission is

possible from the last addressed IC after the posi-

Data fromµP

ENABLE

tive going edge of the ENABLE signal if the ENA-

BLE signal remains high and the CLOCK impulses

are present on the line. The µP in effect clocks out

the data from the chip. When an IC is able to send

information in the bidirectional way, the µP decides

whether to take all information, to suppress com-

pletely the information or to stop the transfer after

any bit.

This reply word, synchronized to the clock from µP,

is sent only once. Should a subsequent clock im-

pulse be present on the clock line, it will switch the

IC in question to high impedance.

The register, from which the bidirectional informa-

tion comes, is addressed with the IC address.

When more than one bidirectional register exists,

the selection is made by the previously selected

subaddress.

Data to µP

CLOCK

DATA

datatransfer

datatransfer

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