ATEVK1104 Atmel, ATEVK1104 Datasheet - Page 134

• Manufacturer Part Number: ATEVK1104
• Description: KIT DEV/EVAL FOR AVR32 AT32UC3A
• Manufacturer: Atmel
• Series: AVR®32r
• Type: MCUr

Specifications of ATEVK1104

• Contents: Evaluation Board, Software and Documentation
• Processor To Be Evaluated: AT32UC3A3
• Data Bus Width: 32 bit
• Interface Type: USB, SPI, USART
• Silicon Manufacturer: Atmel
• Core Architecture: AVR
• Core Sub-architecture: AVR UC3
• Silicon Core Number: AT32UC3A3256
• Silicon Family Name: AVR
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT32UC3A3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

19.5.1.1
19.5.1.2
19.5.2
19.5.2.1
32058J–AVR32–04/11
Round-Robin Arbitration
Undefined Length Burst Arbitration
Slot Cycle Limit Arbitration
Round-Robin Arbitration without Default Master
In order to avoid long slave handling during undefined length bursts (INCR), the Bus Matrix pro-
vides specific logic in order to re-arbitrate before the end of the INCR transfer. A predicted end
of burst is used as a defined length burst transfer and can be selected from among the following
five possibilities:
This selection can be done through the field ULBT of the Master Configuration Registers
(MCFG).
The Bus Matrix contains specific logic to break long accesses, such as very long bursts on a
very slow slave (e.g., an external low speed memory). At the beginning of the burst access, a
counter is loaded with the value previously written in the SLOT_CYCLE field of the related Slave
Configuration Register (SCFG) and decreased at each clock cycle. When the counter reaches
zero, the arbiter has the ability to re-arbitrate at the end of the current byte, half word or word
transfer.
This algorithm allows the Bus Matrix arbiters to dispatch the requests from different masters to
the same slave in a round-robin manner. If two or more master requests arise at the same time,
the master with the lowest number is first serviced, then the others are serviced in a round-robin
manner.
There are three round-robin algorithms implemented:
This is the main algorithm used by Bus Matrix arbiters. It allows the Bus Matrix to dispatch
requests from different masters to the same slave in a pure round-robin manner. At the end of
the current access, if no other request is pending, the slave is disconnected from all masters.
This configuration incurs one latency cycle for the first access of a burst. Arbitration without
default master can be used for masters that perform significant bursts.
4. Slot Cycle Limit: When the slot cycle counter has reached the limit value indicating that
1. Infinite: No predicted end of burst is generated and therefore INCR burst transfer will
2. One beat bursts: Predicted end of burst is generated at each single transfer inside the
3. Four beat bursts: Predicted end of burst is generated at the end of each four beat
4. Eight beat bursts: Predicted end of burst is generated at the end of each eight beat
5. Sixteen beat bursts: Predicted end of burst is generated at the end of each sixteen beat
• Round-Robin arbitration without default master
• Round-Robin arbitration with last default master
• Round-Robin arbitration with fixed default master
the current master access is too long and must be broken.
page 134.
never be broken.
INCP transfer.
boundary inside INCR transfer.
boundary inside INCR transfer.
boundary inside INCR transfer.
See Section “19.5.1.2” on
AT32UC3A
134