HD6433832S Datasheet, PDF (335/560 Pages) Renesas Technology Corp – single-chip microcomputers

13.3.2 Relation of LCD RAM to Display
The relation of the LCD RAM to segments depends on the duty cycle. LCD RAM memory maps
for each duty cycle when segments are not expanded externally are shown in figures 13.3 to 13.6.
When segments are expanded externally, the LCD RAM memory maps for each duty cycle are as
shown in figures 13.7 to 13.10. It is also possible to use only external segments and not use the
segment pins on this chip, in which case the LCD RAM memory map is as shown in figure 13.11.
After setting the registers that control the LCD display, write data to the area corresponding to the
duty cycle selected, using the same instructions as for the ordinary RAM. If the display is switched
on, the data will be displayed automatically. Both word and byte access instructions can be used
for writing to the LCD RAM.
13.3.3 Connection to HD66100
To expand the number of segments externally, connect the H8/3834 Series to the HD66100
segment chip. The HD66100 chip provides an additional 80 segments. When external segments
are used, set bit SGX in LPCR for use of pins SEG₄₀ to SEG₃₇ as external segment expansion
signal pins. Data will be output starting from LCD RAM pin SEG₃₇. When bits SGS3 to SGS0 in
LPCR are set to 0000, data will be output starting from LCD RAM pin SEG₁.
Figure 13.12 shows typical connections to the HD66100. The output level is determined by the
combination of data pins and pin M; but that combination differs between the H8/3834 Series and
the HD66100. Table 13.3 shows the output level of the LCD driver power supply.
Figure 13.13 shows the common and segment waveforms at each duty.
If bit ACT = 0, then if CL₂ = 0, CL₁ = 0 and M = 0, DO stops with the data output at that moment
(1 or 0). In standby mode the expansion pins are in the high-impedance (floating) state.
External expansion increases the load on the LCD panel, as a result of which the internal power
supply may not have sufficient capacity. In that case refer to 13.3.5, Boosting the LCD Driver
Power Supply.
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