ATmega6490 Atmel Corporation, ATmega6490 Datasheet - Page 230
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ATmega6490
Manufacturer Part Number
ATmega6490
Description
Manufacturer
Atmel Corporation
Specifications of ATmega6490
Flash (kbytes)
64 Kbytes
Pin Count
100
Max. Operating Frequency
16 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
69
Ext Interrupts
32
Usb Speed
No
Usb Interface
No
Spi
2
Twi (i2c)
1
Uart
1
Segment Lcd
160
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
4
Eeprom (bytes)
2048
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
3
Output Compare Channels
4
Input Capture Channels
1
Pwm Channels
4
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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23.1.6
23.1.7
23.1.8
23.1.9
230
ATmega329/3290/649/6490
LCD Contrast Controller/Power Supply
LCDCAP
LCD Buffer Driver
Display requirements
To energize a segment, an absolute voltage above a certain threshold must be applied. This is
done by letting the output voltage on corresponding COM pin and SEG pin have opposite phase.
For display with more than one common, one (1/2 bias) or two (1/3 bias) additional voltage lev-
els must be applied. Otherwise, non-energized segments on COM0 would be energized for all
non-selected common.
Addressing COM0 starts a frame by driving opposite phase with large amplitude out on COM0
compared to none addressed COM lines. Non-energized segments are in phase with the
addressed COM0, and energized segments have opposite phase and large amplitude. For
waveform figures refer to
LCDDR0 is multiplexed into the decoder. The decoder is controlled from the LCD timing and
sets up signals controlling the analog switches to produce an output waveform. Next, COM1 is
addressed, and latched data from LCDDR9 - LCDDR5 is input to decoder. Addressing continu-
ous until all COM lines are addressed according to number of common (duty). The display data
are latched before a new frame start.
The peak value (V
by software from 2.6V to 3.35V independent of V
until V
An external capacitor (typical > 470 nF) must be connected to the LCDCAP pin as shown in
ure
ripple on V
Figure 23-2. LCDCAP Connection
Intermediate voltage levels are generated from buffers/drivers. The buffers are active the
amount of time specified by LCDDC[2:0] in LCDCCR. Then LCD output pins are tri-stated and
buffers are switched off. Shortening the drive time will reduce power consumption, but displays
with high internal resistance or capacitance may need longer drive time to achieve sufficient
contrast.
When using more than one common pin, the maximum period the LCD drivers can be turned on
for each voltage transition on the LCD pins is 50% of the prescaled LCD clock period, clk
To avoid flickering, it is recommended to keep the framerate above 30Hz, thus giving a maxi-
mum drive time of approximately 2ms when using 1/2 or 1/4 duty, and approximately 2.7ms
23-2. This capacitor acts as a reservoir for LCD power (V
LCD
has reached its target value.
LCD
but increases the time until V
LCD
) on the output waveform determines the LCD Contrast. V
“Mode of Operation” on page
62
63
64
LCD
1
reaches its target value.
CC
2
. An internal signal inhibits output to the LCD
3
231. Latched data from LCDDR4 -
LCD
). A large capacitance reduces
LCD
2552K–AVR–04/11
is controlled
LCD_PS
Fig-
.