CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS

4RESET command

This command is used to change the currently selected slave to non-selected status. All slaves

can be placed in non-selected status by sending the RESET command.

Fig. 5-59 RESET Command Transfer Format

M

RESET

Command

S

ACK

Remarks M : Output by master

S: Output by slave

CHGMST command

This command passes mastership to the currently selected slave.

Fig. 5-60 CHGMST Command Transfer Format

M

CHGMST

Command

S

ACK

S

Data

Data

S

ACK

Remarks M : Output by master

S : Output by slave

When a slave receives the CHGMST command, it determines whether it can assume mastership and returns data to the master. This data is as follows:

0FFH : Change of master possible

00H : Change of master not possible

When the slave sends this data, it compares the SIO contents before and after transmission and if they do not match an error is generated and no ACK is returned.

If there is no error after the 0FFH data has been transmitted, the master operates as a slave and the slave operates as the master from that point on.

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NEC PD75402A, PD75P402 user manual Reset command, ➄ Chgmst command, 124