A000047 Arduino, A000047 Datasheet - Page 39

• Manufacturer Part Number: A000047
• Description: MCU, MPU & DSP Development Tools Mega2560
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000047

• Processor To Be Evaluated: ATmega2560
• Interface Type: USB, I2C, SPI
• Dimensions: 4 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega2560

2549M–AVR–09/10
• 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 60 Kbytes 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
XMMn bits to access all 64 Kbytes locations of the External Memory.
Table 8-4.
XMM2
“Using all 64 Kbytes 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 56 Kbytes space)
No Address high bits
7
6
5
4
3
2
33, it is possible to use the
Released Port Pins
Table
PC7 - PC6
PC7 - PC5
PC7 - PC4
PC7 - PC3
PC7 - PC2
Full Port C
8-4. As described
None
PC7
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