ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 39

• Manufacturer Part Number: ATmega1281R231
• Manufacturer: Atmel Corporation

Specifications of ATmega1281R231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 16 MHz
• Max I/o Pins: 54
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 6
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

2549N–AVR–05/11
• Bit 7– XMBK: External Memory Bus-keeper Enable
Writing XMBK to one enables the bus keeper on the AD7:0 lines. When the bus keeper is
enabled, AD7:0 will keep the last driven value on the lines even if the XMEM interface has tri-
stated the lines. Writing XMBK to zero disables the bus keeper. XMBK is not qualified with SRE,
so even if the XMEM interface is disabled, the bus keepers are still activated as long as XMBK is
one.
• Bit 6:3 – Res: Reserved Bits
These bits are reserved and will always read as zero. When writing to this address location,
write these bits to zero for compatibility with future devices.
• Bit 2:0 – XMM2, XMM1, XMM0: External Memory High Mask
When the External Memory is enabled, all Port C pins are default used for the high address byte.
If the full 60Kbytes address space is not required to access the External Memory, some, or all,
Port C pins can be released for normal Port Pin function as described in
in
bits to access all 64Kbytes locations of the External Memory.
Table 9-4.
XMM2
“Using all 64Kbytes Locations of External Memory” on page
0
0
0
0
1
1
1
1
XMM1
0
0
1
1
0
0
1
1
Port C Pins Released as Normal Port Pins when the External Memory is Enabled
XMM0
0
1
0
1
0
1
0
1
# Bits for External Memory Address
ATmega640/1280/1281/2560/2561
8 (Full 56Kbytes space)
No Address high bits
7
6
5
4
3
2
33, it is possible to use the XMMn
Released Port Pins
Table
PC7 - PC6
PC7 - PC5
PC7 - PC4
PC7 - PC3
PC7 - PC2
Full Port C
9-4. As described
None
PC7
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