UPD77533 datasheet(24/104 Pages) RENESAS

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Data Sheet S15671EJ4V0DS

µµµµPD77533

4.3

Timeout Error (No Response from

µµµµPD77533)

If there is no response from the

µPD77533 to a command from the host CPU, the host CPU must perform the

following control processing.

(1) If a character timeout has been set in the

µPD77533

A character timeout occurs in the

µPD77533 and the host CPU is sent the Error Status command (CMD-ID:

0x3F) from the

µPD77533. After receiving the Error Status command (CMD-ID: 0x3F), the host CPU resends

the previous command (see Figure 4-7).

(2) If a character timeout has not been set in the

µPD77533

If there is no response from the

µPD77533 for 100 ms or more, the host CPU sends the µPD77533 ‘3F’ in

one byte units and waits to receive the Error Status command (CMD-ID: 0x3F) from the

µPD77533. After

receiving the Error Status command (CMD-ID: 0x3F), the host CPU resends the previous command (see

Figure 4-8).

It is recommended to preset a character timeout in the

µPD77533 because if not (case (2) above), it often takes a

long time for the

µPD77533 to be restored.

Figure 4-7. Processing Flow When There Is No Response from

µµµµPD77533 (Character Timeout Set)

PD77533

Host CPU

No response from

PD77533,

timer operating

Command

Previous command

re-sent

Command

Timer timeout

Error Status (Timeout Error)

UPD77533 데이터시트(PDF) 24 Page - Renesas Technology Corp