UPD77533 datasheet(43/104 Pages) RENESAS

43 / 104 page

Data Sheet S15671EJ4V0DS

µµµµPD77533

12.4.4 Checksum

The lower 16 bits of the sum of all the bytes from the 1-byte CMD-ID to the byte preceding the checksum are used

for the checksum.

12.4.5 End

All commands and responses end with <CR><LF>.

<CR> = 0x0D, <LF> = 0x0A

12.5 Packeting and De-packeting Server Commands

When issued by the LS, server commands are not in the packet format required for interfacing between the

µPD77533 and host CPU, and must therefore be “packeted” by the host CPU. The host CPU must similarly “de-

packet” packeted data from the

µPD77533 before sending it to the LS.

Figure 12-6. Packeting and De-packeting Server Commands

13. ACK, NACK, ERROR STATUS

In communication between the

µPD77533 and the host CPU, the transmission and reception of server and

extension commands and responses is confirmed using ACK and NACK.

Table 13-1. ACK and NACK Applications

Type

Description

ACK

Indicates that the command was received.

NACK (error status)

Indicates that the command cannot be received for some reason.

PD77533

Host CPU

Server command

(packet form)

Packet/de-packet

processing

Server command

(unpacketed state)

Local command,

extension command

(packet form)

UPD77533 Datasheet(PDF) 43 Page - Renesas Technology Corp