C8051F960-B-GM Datasheet, PDF (334/492 Pages) Silicon Laboratories – Ultra Low Power 128K, LCD MCU Family

C8051F96x
26. LCD Segment Driver
C8051F96x devices contain an LCD segment driver and on-chip bias generation that supports static, 2-
mux, 3-mux and 4-mux LCDs with 1/2 or 1/3 bias. The on-chip charge pump with programmable output
voltage allows software contrast control which is independent of the supply voltage. LCD timing is derived
from the SmaRTClock oscillator to allow precise control over the refresh rate.
The C8051F96x uses special function registers (SFRs) to store the enabled/disabled state of individual
LCD segments. All LCD waveforms are generated on-chip based on the contents of the LCD0Dn registers
An LCD blinking function is also supported. A block diagram of the LCD segment driver is shown in
Figure 26.1.
VBAT
VLCD
10 uF
LCD Segment Driver
Charge
Pump
Power
Management
Bias
Generator
SmaRTClock
Clock
Divider
LCD Clock
LCD State Machine
Configuration
Registers
Data Registers
Port
Drivers
32 Segment
Pins
4 COM Pins
Figure 26.1. LCD Segment Driver Block Diagram
26.1. Configuring the LCD Segment Driver
The LCD segment driver supports multiple mux options: static, 2-mux, 3-mux, and 4-mux mode. It also
supports 1/2 and 1/3 bias options. The desired mux mode and bias is configured through the LCD0CN reg-
ister. A divide value may also be applied to the SmaRTClock output before being used as the LCD0 clock
source.
The following procedure is recommended for using the LCD Segment Driver:
1. Initialize the SmaRTClock and configure the LCD clock divide settings in the LCD0CN register.
2. Determine the GPIO pins which will be used for the LCD function.
3. Configure the Port I/O pins to be used for LCD as Analog I/O.
4. Configure the LCD size, mux mode, and bias using the LCD0CN register.
5. Enable the LCD bias and clock gate by writing 0x50 to the LCD0MSCN register.
6. Configure the device into the desired Contrast Control Mode.
7. If VIO is internally or externally shorted to VBAT, disable the VLCD/VIO Supply Comparator using the
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Rev. 1.0