UPD77533 datasheet(20/104 Pages) RENESAS

20 / 104 page

Data Sheet S15671EJ4V0DS

µµµµPD77533

4. COMMUNICATION ERROR CONTROL

The following three types of communication errors (command errors hereafter) may occur in communication

between the

µPD77533 and the host CPU.

One of the following three error types is included in the data field of the Error Status command (CMD-ID: 0x3F).

Table 4-1. Types of Command Errors

Error Type

Error Definition

Format error

The format of the command is incorrect.

Timeout error

The specified time has elapsed while command packet reception is not complete, or the

µPD77533 does not respond to a command from the host CPU.

Undefined CMD-ID error

An undefined numeric value has been used as the CMD-ID.

4.1

Format Error, Undefined CMD-ID Error

The control flow used when a format or undefined CMD-ID error occurs is described below.

For timeout error details, see 4.2 Timeout Error (Command Packet Interruption) and 4.3 Timeout Error (No

Response from

µµµµPD77533).

Caution The control flow used when a format or undefined CMD-ID error occurs during an uplink

(

µµµµPD77533

Host CPU) differs depending on whether the command from the host CPU is a

server command or a local command.

4.1.1 When command from host CPU is server command

When the command is a server command, packet transmission/reception is confirmed on a packet by packet

basis using ACK and NACK. For details of the ACK and NACK formats, see 13 ACK, NACK ERROR STATUS.

If an error occurs during an uplink (see Figure 4-1), the host CPU sends NACK to the

µPD77533, which then re-

sends the same packet. The

µPD77533 can send the next packet after receiving ACK from the host CPU.

If an error occurs during a downlink (host CPU

µPD77533) (see Figure 4-2), the µPD77533 sends NACK to the

host CPU, which must then re-send the same packet. The host CPU can send the next packet after receiving ACK

from the

µPD77533.

UPD77533 датащи(PDF) 20 Page - Renesas Technology Corp