AT32UC3L064_1 ATMEL [ATMEL Corporation], AT32UC3L064_1 Datasheet - Page 750

• Manufacturer Part Number: AT32UC3L064_1
• Description: AVR32 32-bit Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

31.4.11.1
31.4.11.2
31.4.11.3
31.4.11.4
32099A–AVR32–06/09
SAB Address Mode
Block Transfer
Canceling a SAB Access
Busy Reporting
which is linked to the JTAG through a bus master module, which also handles synchronization
between the TCK and SAB clocks.
For more information about the SAB and a list of SAB slaves see the Service Access Bus
chapter.
The MEMORY_SIZED_ACCESS instruction allows a sized read or write to any 36-bit address
on the bus. MEMORY_WORD_ACCESS is a shorthand instruction for 32-bit accesses to any
36-bit address, while the NEXUS_ACCESS instruction is a Nexus-compliant shorthand instruc-
tion for accessing the 32-bit OCD registers in the 7-bit address space reserved for these. These
instructions require two passes through the Shift-DR TAP state: one for the address and control
information, and one for data.
To increase the transfer rate, consecutive memory accesses can be accomplished by the
MEMORY_BLOCK_ACCESS instruction, which only requires a single pass through Shift-DR for
data transfer only. The address is automatically incremented according to the size of the last
SAB transfer.
It is possible to abort an ongoing SAB access by the CANCEL_ACCESS instruction, to avoid
hanging the bus due to an extremely slow slave.
As the time taken to perform an access may vary depending on system activity and current chip
frequency, all the SAB access JTAG instructions can return a busy indicator. This indicates
whether a delay needs to be inserted, or an operation needs to be repeated in order to be suc-
cessful. If a new access is requested while the SAB is busy, the request is ignored.
The SAB becomes busy when:
The SAB becomes ready again when:
What to do if the busy bit is set:
• Entering Update-DR in the address phase of any read operation, e.g., after scanning in a
• Entering Update-DR in the data phase of any write operation, e.g., after scanning in data for
• Entering Update-DR during a MEMORY_BLOCK_ACCESS.
• Entering Update-DR after scanning in a counter value for SYNC.
• Entering Update-IR after scanning in a MEMORY_BLOCK_ACCESS if the previous access
• A read or write operation completes.
• A SYNC countdown completed.
• A operation is cancelled by the CANCEL_ACCESS instruction.
• During Shift-IR: The new instruction is selected, but the previous operation has not yet
NEXUS_ACCESS address with the read bit set.
a NEXUS_ACCESS write.
was a read and data was scanned after scanning the address.
completed and will continue (unless the new instruction is CANCEL_ACCESS). You may
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