HD64570 Datasheet, PDF (73/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

Bit name
Read/Write
Initial value
7
6
5
4
3
2
1
0
— — ——
——
— IOSTP
— — — — — — — R/W
0
0
0
0
0
0
0
0
I/O stop
0: No transition to system stop mode
1: Transition to system stop mode
Note: Bit 7–bit 1 are reserved. These bits always read 0 and must be set to 0.
Bits 7−1: Reserved. These bits always read 0 and must be set to 0.
Bit 0 (IOSTP: I/O Stop): Controls transition to low-power mode (system stop mode).
IOSTP = 0: The SCA remains in its current operating mode and does not enter system stop mode.
IOSTP = 1: The SCA enters system stop mode. Registers cannot be written or read in this
mode, so once it is set to 1 to enter system stop mode, the IOSTP bit cannot be cleared to 0 except
by a reset. Figure 3.3 shows transition timing in system stop mode.
Rev. 0, 07/98, page 57 of 453