ATMEGA169 ATMEL [ATMEL Corporation], ATMEGA169 Datasheet - Page 222

• Manufacturer Part Number: ATMEGA169
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

222
ATmega169/V
Table 96. LCD Prescaler Select
• Bit 3 – Res: Reserved Bit
This bit is reserved bit in the ATmega169 and will always read as zero.
• Bits 2:0 – LCDCD2:0: LCD Clock Divide 2, 1, and 0
The LCDCD2:0 bits determine division ratio in the clock divider. The various selections
are shown in Table 97. This Clock Divider gives extra flexibility in frame rate selection.
Table 97. LCD Clock Divide
The frame frequency can be calculated by the following equation:
Where:
LCDCD2
LCDPS2
N = prescaler divider (16, 64, 128, 256, 512, 1024, 2048, or 4096).
K = 8 for duty = 1/4, 1/2, and static.
K = 6 for duty = 1/3.
D = Division factor (see Table 97).
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
LCDCD1
LCDPS1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
LCDCD0
LCDPS0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Prescaler divided by
Output from
clk
clk
clk
f
Prescaler
clk
clk
clk
frame
clk
clk
clk
LCD
LCD
LCD
LCD
LCD
LCD
Output from
LCD
LCD
LCD
/1024
/2048
/4096
/128
/256
/512
/16
/64
=
/N
(D):
1
2
3
4
5
6
7
8
------------------------- -
(
K N D
f
clk
⋅
LCD
⋅
Duty = 1/4, and Frame Rate = 64 Hz
Frequency when LCDCD2:0 = 0,
Applied Prescaled LCD Clock
)
and Duty = 1/4, gives a frame
clk
LCD
130 kHz
260 kHz
520 kHz
8.1 kHz
66 kHz
33 kHz
1 MHz
2 MHz
= 32.768 kHz, N = 16,
rate of:
85.3 Hz
51.2 Hz
42.7 Hz
36.6 Hz
256 Hz
128 Hz
64 Hz
32 Hz
2514P–AVR–07/06