Module Standby Mode - Renesas F-ZTAT H8 Series Hardware Manual

13. Dot Matrix LCD Controller (H8/3857 Group)
13.3.9

Module Standby Mode

The LCD controller has a module standby function that enables low power consumption to be
achieved. In module standby mode, the built-in step-up circuit and op-amps are halted, and
segment and common outputs go to the V
register data is retained, except for the DISP and OPON bits in control register 2 (LR1). The
control registers can still be accessed in the module standby state. Figure 13.12 shows the
procedures for initiating and clearing module standby mode. The initiation and clearing
procedures must be followed exactly in order to protect the display memory contents.
When the CPU is placed in standby mode, set the LSBY bit in control register 1 (LR0) to 1 before
executing the standby instruction. After clearing standby mode, follow the module standby
clearing procedure to start display.
Initiation
Clearing
Figure 13.12 Module Standby Mode and Standby Mode Initiation and Clearing Procedures
Rev.3.00 Jul. 19, 2007 page 360 of 532
REJ09B0397-0300
(display-off state) level. Display RAM and internal
SS
Set LSBY to 1
Module standby mode initiated
Clear LSBY to 0
Wait for step-up circuit power
supply to stabilize
Set OPON to 1
Wait for op-amps to stabilize
Set DISP to 1
Internal operation halts
Step-up operation halts
Internal operation starts
Step-up operation starts
Display starts