ra8806 RAIO Technology Inc., ra8806 Datasheet - Page 68

• Manufacturer Part Number: ra8806
• Description: Two Layers Character/graphic Lcd Controller
• Manufacturer: RAIO Technology Inc.

Preliminary Version 1.2
RAiO
6-9
TECHNOLOGY INC.
RA8806 provide a set of programmable PWM (Pulse Width Modulation) for LCD contrast adjustment.
The PWM frequency and duty can be set by register. And the driving capability of PWM output pin is
larger than other output pin, about 4 multiples of normal output. Besides, if the PWM function is disable,
it can use as normal IO signal. The relative function setting please refers to the table below.
The following are two examples for the PWM output (pin “PWM_OUT”):
PWM
PDCR
Reg.
PCR
Bit_Num
T
Example-1:
System Clock = 10Mhz,
Register PCR Bit[3:0] = 0001b
Register PDCR Bit[7:0] = 0Fh
Example-2:
System Clock = 10Mhz,
Register PCR Bit[3:0] = 0010b
Register PDCR Bit[7:0] = 7Fh
Bit [3:0]
Bit [7:0]
H
Bit 7
T
T
T
T
T
T
T
PWM
H
L
PWM
H
L
PWM function enable
Clock source divide ratio select
PWM Duty Cycle Select
H
= (256-16) * (1/ 5MHz) = 48µs
= (256-128) * (1/ 2.5MHz) = 51.2µs
= 16*(1/5MHz) = 3.2µs
= 128*(1/2.5MHz) = 51.2µs
Figure 6-37 : PWM_OUT Pulse
= 256*(1/5MHz) = 51.2µs
= 256*(1/2.5MHz) = 102.4 µs
T
T
PWM
PWM
T
L
T
L
Table 6-21
Description
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Clock Source = 10MHz/2 = 5MHz
Clock Source = 10MHz/4 = 2.5MHz
Two Layers Character/Graphic LCD Controller
Reference
REG[D0h]
REG[D1h]
www.raio.com.tw
RA8806