CY8C5466AXI-064 Cypress Semiconductor Corp, CY8C5466AXI-064 Datasheet - Page 12

• Manufacturer Part Number: CY8C5466AXI-064
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY8C5466AXI-064

• Lead Free Status / Rohs Status: Compliant

There are two PHUB masters: the CPU and the DMA controller.
Both masters may initiate transactions on the bus. The DMA
channels can handle peripheral communication without CPU
intervention. The arbiter in the central hub determines which
DMA channel is the highest priority if there are multiple requests.
4.3.1 PHUB Features
Table 4-3. PHUB Spokes and Peripherals
4.3.2 DMA Features
Document Number: 001-66238 Rev. *A
PHUB Spokes
CPU and DMA controller are both bus masters to the PHUB
Eight Multi-layer AHB Bus parallel access paths (spokes) for
peripheral access
Simultaneous CPU and DMA access to peripherals located on
different spokes
Simultaneous DMA source and destination burst transactions
on different spokes
Supports 8, 16, 24, and 32-bit addressing and data
24 DMA channels
Each channel has one or more Transaction Descriptors (TDs)
to configure channel behavior. Up to 127 total TDs can be
defined
TDs can be dynamically updated
Eight levels of priority per channel
Any digitally routable signal, the CPU, or another DMA channel,
can trigger a transaction
Each channel can generate up to two interrupts per transfer
Transactions can be stalled or canceled
Supports transaction size of infinite or 1 to 64k bytes
Large transactions may be broken into smaller bursts of 1 to
127 bytes
0
1
2
3
4
5
6
7
SRAM
IOs,
PHUB local configuration,
Clocks, IC, EEPROM,
interface
Analog interface and
USB, CAN,
DFB
UDBs group 1
UDBs group 2
PICU
I
2
C,
Timers, Counters, and PWMs
Peripherals
trim,
Flash programming
Power
Decimator
PRELIMINARY
manager,
4.3.3 Priority Levels
The CPU always has higher priority than the DMA controller
when their accesses require the same bus resources. Due to the
system architecture, the CPU can never starve the DMA. DMA
channels of higher priority (lower priority number) may interrupt
current DMA transfers. In the case of an interrupt, the current
transfer is allowed to complete its current transaction. To ensure
latency limits when multiple DMA accesses are requested
simultaneously, a fairness algorithm guarantees an interleaved
minimum percentage of bus bandwidth for priority levels 2
through 7. Priority levels 0 and 1 do not take part in the fairness
algorithm and may use 100% of the bus bandwidth. If a tie occurs
on two DMA requests of the same priority level, a simple round
robin method is used to evenly share the allocated bandwidth.
The round robin allocation can be disabled for each DMA
channel, allowing it to always be at the head of the line. Priority
levels 2 to 7 are guaranteed the minimum bus bandwidth shown
in
satisfied their requirements.
Table 4-4. Priority Levels
When the fairness algorithm is disabled, DMA access is granted
based solely on the priority level; no bus bandwidth guarantees
are made.
4.3.4 Transaction Modes Supported
The flexible configuration of each DMA channel and the ability to
chain multiple channels allow the creation of both simple and
complex use cases. General use cases include, but are not
limited to:
4.3.4.1 Simple DMA
In a simple DMA case, a single TD transfers data between a
source and sink (peripherals or memory location). The basic
timing diagrams of DMA read and write cycles are shown in
Figure
to the Technical Reference Manual.
TDs may be nested and/or chained for complex transactions
Table 4-4
PSoC
Priority Level
4-2. For more description on other transfer modes, refer
0
1
2
3
4
5
6
7
after the CPU and DMA priority levels 0 and 1 have
®
5: CY8C54 Family Datasheet
% Bus Bandwidth
100.0
100.0
50.0
25.0
12.5
6.2
3.1
1.5
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