CHAPTER 15 VFD CONTROLLER/DRIVER
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User’s Manual U11302EJ4V0UM
(3) Display mode register 2 (DSPM2) (see Figure 15-5)
DSPM2 is the register that holds the number of mask bits in the display data storage area when display mode
2 (DSPM05 = 1) is selected by display mode register 0 (DSPM0). By using this register to mask the part
of the display data that does not need to be rewritten, the software workload is reduced.
Mask bits are assigned from S0 (= the least significant bit of the lowest address in the display output area
defined by bits 0 to 4 of DSPM0).
DSPM2 is set with an 8-bit memory manipulation instruction.
RESET input sets DSPM2 to 00H.
The following illustration shows the status of the display data memory when the number of segments is 32
and the number of mask bits is 11.
S31
S24 S23
Bit 7
0 7
S16 S15
0 7
0 7
0
S8
S7
S0
11 bits
.......................
...................
....................
....................
FA50H
FA40H
: The shaded part shows the area in which display data is rewritable during display
: The slashed part shows the area in which display data is not rewritable during display (display data are fixed)
FA70H
FA60H
Caution The number of mask bits specified must be below the total number of display outputs
defined by display mode register 0 (DSPM0).