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13.3.8
Connection to HD66100
If the segments are to be expanded externally, an HD66100 should be connected. Connecting one
HD66100 provides 80-segment expansion. When carrying out external expansion, select the
external expansion signal function of pins SEG
to SEG
with the SGX bit in LPCR, and set bits
32
29
SGS3 to SGS0 to 0000 or 0001. Data is output externally from SEG
of the LCD RAM. SEG
to
1
28
SEG
function as ports.
1
Figure 13-18 shows examples of connection to an HD66100. The output level is determined by a
combination of the data and the M pin output, but these combinations differ from those in the
HD66100. Table 13-3 shows the output levels of the LCD drive power supply, and figures 13-15
and 13-16 show the common and segment waveforms for each duty cycle.
When ACT is cleared to 0, operation stops with CL
= 0, CL
= 0, M = 0, and DO at the data value
2
1
(1 or 0) being output at that instant. In standby mode, the expansion pins go to the high-
impedance (floating) state.
When external expansion is implemented, the load in the LCD panel increases and the on-chip
power supply may not provide sufficient current capacity. In this case, measures should be taken
as described in section 13.3.7, Boosting the LCD Drive Power Supply.
354
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