AT32UC3L0256_14 Datasheet, PDF (784/852 Pages) ATMEL Corporation – Read-modify-write Instructions and Atomic Bit Manipulation

AT32UC3L0128/256
The 4 MSB of the 36 bit SAB address are submitted together with the size field (2 bits). Then fol-
lows the 4 remaining address bytes and finally the data bytes. The size of the transfer is
specified using the values from the following table:
Table 31-42. Size Field Decoding
Size field
00
01
10
11
Description
Byte transfer
Halfword transfer
Word transfer
Reserved
Below is an example write command:
1. 0x55 (sync)
2. 0x80 (command)
3. 0x00 (length MSB)
4. 0x09 (length LSB)
5. 0x25 (size and address MSB, the two MSB of this byte are unused and set to zero)
6. 0x00
7. 0x00
8. 0x00
9. 0x04 (address LSB)
10. 0xCA
11. 0xFE
12. 0xBA
13. 0xBE
14. 0xXX (CRC MSB)
15. 0xXX (CRC LSB)
The length field is set to 0x0009 because there are 9 bytes of additional data: 5 address and size
bytes and 4 bytes of data. The address and size field indicates that words should be written to
address 0x500000004. The data written to 0x500000004 is 0xCAFEBABE.
Table 31-43. MEMORY_WRITE Details
Command
Details
Command value
0x80
Additional data
Size, Address and Data
Possible responses
0xC2: MEMORY_READWRITE_STATUS (Section 31.6.8.5)
0x41: NACK (Section 31.6.8.2)
31.6.7.10
MEMORY_READ
This command enables reading of memory/registers on the Service Access Bus (SAB). The
MEMORY_READ command allows words, halfwords, and bytes to be read from a continuous
sequence of addresses in one operation. The user must supply:
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