ATmega128A Atmel Corporation, ATmega128A Datasheet - Page 27

• Manufacturer Part Number: ATmega128A
• Manufacturer: Atmel Corporation

Specifications of ATmega128A

• Flash (kbytes): 128 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• 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): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

7.5.8
8151H–AVR–02/11
Using all Locations of External Memory Smaller than 64 Kbytes
Figure 7-9.
Note:
Since the external memory is mapped after the internal memory as shown in
external memory is not addressed when addressing the first 4,352bytes of data space. It may
appear that the first 4,352bytes of the external memory are inaccessible (external memory
addresses 0x0000 to 0x10FF). However, when connecting an external memory smaller than
64Kbytes, for example 32Kbytes, these locations are easily accessed simply by addressing from
address 0x8000 to 0x90FF. Since the External Memory Address bit A15 is not connected to the
external memory, addresses 0x8000 to 0x90FF will appear as addresses 0x0000 to 0x10FF for
the external memory. Addressing above address 0x90FF is not recommended, since this will
address an external memory location that is already accessed by another (lower) address. To
the Application software, the external 32Kbytes memory will appear as one linear 32Kbytes
address space from 0x1100 to 0x90FF. This is illustrated in
refers to the ATmega103 compatibility mode, configuration A to the non-compatible mode.
When the device is set in Atmel
space is 4,096bytes. This implies that the first 4,096bytes of the external memory can be
accessed at addresses 0x8000 to 0x8FFF. To the Application software, the external 32Kbytes
memory will appear as one linear 32Kbytes address space from 0x1000 to 0x8FFF.
System Clock (CLK
DA7:0 (XMBK = 0)
DA7:0 (XMBK = 1)
1. SRWn1 = SRW11 (upper sector) or SRW01 (lower sector), SRWn0 = SRW10 (upper sector) or
SRW00 (lower sector).
The ALE pulse in period T7 is only present if the next instruction accesses the RAM (internal
or external).
DA7:0
A15:8
CPU
ALE
WR
RD
External Data Memory Cycles with SRWn1 = 1 and SRWn0 = 1
)
Prev. addr.
Prev. data
Prev. data
Prev. data
T1
Address
Address
Address
T2
®
AVR
XX
®
ATmega103 compatibility mode, the internal address
Address
T3
Data
Data
Data
T4
Figure
T5
7-10. Memory configuration B
ATmega128A
T6
(1)
Figure
T7
7-4, the
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