Datasheet

RL78/L12 CHAPTER 14 LCD CONTROLLER/DRIVER
R01UH0330EJ0200 Rev.2.00 617
Dec 13, 2013
14.3.6 LCD boost level control register (VLCD)
VLCD selects the reference voltage that is to be generated when operating the voltage boost circuit (contrast
adjustment). The reference voltage can be selected from 16 steps.
This register is set by using an 8-bit memory manipulation instruction.
Reset signal generation sets VLCD to 04H.
Figure 14-7. Format of LCD Boost Level Control Register (VLCD)
Address: FFF43H After reset: 04H R/W
Symbol 7 6 5 4 3 2 1 0
VLCD 0 0 0 VLCD4 VLCD3 VLCD2 VLCD1 VLCD0
VLCD4 VLCD3 VLCD2 VLCD1 VLCD0
Reference voltage
selection
(contrast adjustment)
V
L4 voltage
1/3 bias
method
1/4 bias
method
0 0 1 0 0 1.00 V (default) 3.00 V 4.00 V
0 0 1 0 1 1.05 V 3.15 V 4.20 V
0 0 1 1 0 1.10 V 3.30 V 4.40 V
0 0 1 1 1 1.15 V 3.45 V 4.60 V
0 1 0 0 0 1.20 V 3.60 V 4.80 V
0 1 0 0 1 1.25 V 3.75 V 5.00 V
0 1 0 1 0 1.30 V 3.90 V 5.20 V
0 1 0 1 1 1.35 V 4.05 V Setting prohibited
0 1 1 0 0 1.40 V 4.20 V Setting prohibited
0 1 1 0 1 1.45 V 4.35 V Setting prohibited
0 1 1 1 0 1.50 V 4.50 V Setting prohibited
0 1 1 1 1 1.55 V 4.65 V Setting prohibited
1 0 0 0 0 1.60 V 4.80 V Setting prohibited
1 0 0 0 1 1.65 V 4.95 V Setting prohibited
1 0 0 1 0 1.70 V 5.10 V Setting prohibited
1 0 0 1 1 1.75 V 5.25 V Setting prohibited
Other than above Setting prohibited
Cautions 1. The VLCD setting is valid only when the voltage boost circuit is operating.
2. Be sure to set bits 5 to 7 to “0”.
3. Be sure to change the VLCD value after having stopped the operation of the voltage boost
circuit (VLCON = 0).
4. To use the internal voltage boosting method, specify the reference voltage by using the
VLCD register (select the internal boosting method (by setting the MDSET1 and MDSET0 bits
of the LCDM0 register to 01B) if the default reference voltage is used), wait for the reference
voltage setup time (5 ms (min.)), and then set VLCON to 1.
5. With the external resistance division method and the capacitor split method, use the default
value (04H) for the VLCD resistor.