HD66727 Datasheet, PDF (30/97 Pages) Hitachi Semiconductor – Low-Power Dot-Matrix Liquid Crystal Display Controller/Driver with Key Scan Function

HD66727
Instruction Description
Busy Flag/Key Scan Read
The busy flag/key scan read instruction (Figure 5) reads scan data SD3 to SD0 latched into scan registers
SCAN0 to SCAN7, scan cycle state SF1 and SF0, and transfer flag TF, sequentially. It also reads the busy
flag (BF) indicating that the system is now internally operating on a previously received instruction. If BF
is 1, the internal operation is in progress. The next instruction will not be accepted until BF is cleared to 0.
Adjust the data transfer rate so that the last bit of the next instruction is received after BF is cleared to 0.
RS R/W DB7
DB0
0 1 BF SF1 SF0 TF SD3 SD2 SD1 SD0
Figure 5 Busy Flag/Key Scan Read Instruction
Clear Display
The clear display instruction (Figure 6) writes space code 20H (character pattern for character code 20H
must be a blank pattern) into all DDRAM addresses. It then sets DDRAM address 0 into the address
counter. It also sets I/D to 1 (increment mode) in the entry mode set instruction.
RS R/W DB7
DB0
0000000001
Figure 6 Clear Display Instruction
Return Home
The return home instruction (Figure 7) sets DDRAM address 0 into the address counter. The DDRAM
contents do not change. The cursor or blinking goes to the top left of the display.
RS R/W DB7
DB0
0000000010
Figure 7 Return Home Instruction
30