ATSAM3U-EK Atmel, ATSAM3U-EK Datasheet - Page 76

• Manufacturer Part Number: ATSAM3U-EK
• Description: KIT EVAL FOR AT91SAM3U CORTEX
• Manufacturer: Atmel
• Type: MCUr

Specifications of ATSAM3U-EK

• Contents: Board
• Processor To Be Evaluated: SAM3U
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3 V
• Silicon Manufacturer: Atmel
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: SAM3U4E
• Silicon Family Name: SAM3U
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT91SAM3U
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

13.4.5.1
13.4.5.2
13.4.6
76
SAM3U Series
Memory endianness
Directly accessing an alias region
Directly accessing a bit-band region
Figure 13-2. Bit-band mapping
Writing to a word in the alias region updates a single bit in the bit-band region.
Bit[0] of the value written to a word in the alias region determines the value written to the tar-
geted bit in the bit-band region. Writing a value with bit[0] set to 1 writes a 1 to the bit-band bit,
and writing a value with bit[0] set to 0 writes a 0 to the bit-band bit.
Bits[31:1] of the alias word have no effect on the bit-band bit. Writing 0x01 has the same effect as
writing 0xFF. Writing 0x00 has the same effect as writing 0x0E.
Reading a word in the alias region:
“Behavior of memory accesses” on page 72
word accesses to the bit-band regions.
The processor views memory as a linear collection of bytes numbered in ascending order from
zero. For example, bytes 0-3 hold the first stored word, and bytes 4-7 hold the second stored
word. or
• 0x00000000 indicates that the targeted bit in the bit-band region is set to zero
• 0x00000001 indicates that the targeted bit in the bit-band region is set to 1
7
7
0x23FFFFFC
0x2200001C
6
6
“Little-endian format”
5
5
0x200FFFFF
0x20000003
4
4
3
3
0x23FFFFF8
0x22000018
2
2
1
1
0
0
7
7
0x23FFFFF4
0x22000014
6
6
describes how words of data are stored in memory.
5
5
0x200FFFFE
0x20000002
4
4
1MB SRAM bit-band region
3
3
0x23FFFFF0
0x22000010
32MB alias region
2
2
1
1
0
0
describes the behavior of direct byte, halfword, or
7
7
0x23FFFFEC
0x2200000C
6
6
5
5
0x200FFFFD
0x20000001
4
4
3
3
0x23FFFFE8
0x22000008
2
2
1
1
0
0
7
7
0x23FFFFE4
0x22000004
6
6
5
5
0x200FFFFC
0x20000000
4
4
6430D–ATARM–25-Mar-11
3
3
0x23FFFFE0
0x22000000
2
2
1
1
0
0