AT85C5122D-RDRUM datasheet(69/208 Pages) ATMEL

69 / 208 page

AT83R5122, AT8xC5122/23

4202F–SCR–07/2008

Figure 34.

T=0 mode

In T=1 protocol : The maximum interval between the leading edge of the start bit of 2

consecutive characters sent by the ICC is called maximum Character Waiting Time. The

Character Waiting Time shall not exceed (2**CWI + 11) ETUs with 0 =< BWI =< 5. Con-

sequently 12 ETUs =< CWT =< 43 ETUs.

T=1 protocol also specify the maximum Block Waiting Time. This is the time between

the leading edge of the last character sent by the Terminal giving the right to send to the

ICC, and the leading edge of the start bit of the first character sent by the ICC. The

Block Waiting Time shall not exceed (2**BWI*960 + 11) ETUs with 0 =< BWI =< 4. Con-

sequently 971 ETUs =< BWT =< 15371 ETUs.

In T=1 protocol it is possible to extend the Block Waiting Time with the Waiting Time

Extension (WTX). When selected the waiting time becomes BWT*WTX ETUs. The

Waiting Time counter is 32 bit wide to accomodate this feature.

It is possible to take advantage of the automatic reload of the Waiting Time counter with

a start bit in UART mode (T=1 protocol use UART mode) . If the Terminal sends a block

of N characters, and the ICC is supposed to respond immediately after, then the follow-

ing sequence can be used.

While sending the (N-1)th character of the block, the Terminal can write the

SCWT0,1,2,3 with BWImax.

At the start bit of the Nth character, the BWImax is loaded in the Waiting Time counter

During the transmission of the Nth character, the Terminal can write SCWT0,1,2,3 with

the CWImax.

At the start bit of the first character sent by the ICC, the CWImax will be loaded in the

Waiting Time counter.

Figure 35.

T=1 Mode

CHAR 1

CHAR 2

< WT

> GT

BLOC 1

CHAR 1

CHAR 2

CHAR n

BLOC 2

CHAR n+1

CHAR n+2

CHAR n+3

< BWT

< CWT

TRANSMISSION

RECEPTION

AT85C5122D-RDRUM Datasheet(PDF) 69 Page - ATMEL Corporation

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