CY8C5366LTI-053 Cypress Semiconductor Corp, CY8C5366LTI-053 Datasheet - Page 13

• Manufacturer Part Number: CY8C5366LTI-053
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY8C5366LTI-053

• Lead Free Status / Rohs Status: Compliant

4.3.4.2 Auto Repeat DMA
Auto repeat DMA is typically used when a static pattern is
repetitively read from system memory and written to a peripheral.
This is done with a single TD that chains to itself.
4.3.4.3 Ping Pong DMA
A ping pong DMA case uses double buffering to allow one buffer
to be filled by one client while another client is consuming the
data previously received in the other buffer. In its simplest form,
this is done by chaining two TDs together so that each TD calls
the opposite TD when complete.
4.3.4.4 Circular DMA
Circular DMA is similar to ping pong DMA except it contains more
than two buffers. In this case there are multiple TDs; after the last
TD is complete it chains back to the first TD.
4.3.4.5 Indexed DMA
In an indexed DMA case, an external master requires access to
locations on the system bus as if those locations were shared
memory. As an example, a peripheral may be configured as an
SPI or I
master. That address becomes an index or offset into the internal
system bus memory space. This is accomplished with an initial
“address fetch” TD that reads the target address location from
the peripheral and writes that value into a subsequent TD in the
chain. This modifies the TD chain on the fly. When the “address
fetch” TD completes it moves on to the next TD, which has the
new address information embedded in it. This TD then carries
out the data transfer with the address location required by the
external master.
4.3.4.6 Scatter Gather DMA
In the case of scatter gather DMA, there are multiple
noncontiguous sources or destinations that are required to
effectively carry out an overall DMA transaction. For example, a
packet may need to be transmitted off of the device and the
packet elements, including the header, payload, and trailer, exist
in various noncontiguous locations in memory. Scatter gather
DMA allows the segments to be concatenated together by using
multiple TDs in a chain. The chain gathers the data from the
multiple locations. A similar concept applies for the reception of
data onto the device. Certain parts of the received data may need
to be scattered to various locations in memory for software
processing convenience. Each TD in the chain specifies the
location for each discrete element in the chain.
Document Number: 001-66237 Rev. *A
ADDR 16/32
READY
WRITE
DATA
CLK
2
C slave where an address is received by the external
ADDRESS Phase
Basic DMA Read Transfer without wait states
A
DATA Phase
PRELIMINARY
B
Figure 4-2. DMA Timing Diagram
DATA (A)
ADDR 16/32
4.3.4.7 Packet Queuing DMA
Packet queuing DMA is similar to scatter gather DMA but
specifically refers to packet protocols. With these protocols,
there may be separate configuration, data, and status phases
associated with sending or receiving a packet.
For instance, to transmit a packet, a memory mapped
configuration register can be written inside a peripheral,
specifying the overall length of the ensuing data phase. The CPU
can set up this configuration information anywhere in system
memory and copy it with a simple TD to the peripheral. After the
configuration phase, a data phase TD (or a series of data phase
TDs) can begin (potentially using scatter gather). When the data
phase TD(s) finish, a status phase TD can be invoked that reads
some memory mapped status information from the peripheral
and copies it to a location in system memory specified by the
CPU for later inspection. Multiple sets of configuration, data, and
status phase “subchains” can be strung together to create larger
chains that transmit multiple packets in this way. A similar
concept exists in the opposite direction to receive the packets.
4.3.4.8 Nested DMA
One TD may modify another TD, as the TD configuration space
is memory mapped similar to any other peripheral. For example,
a first TD loads a second TD’s configuration and then calls the
second TD. The second TD moves data as required by the
application. When complete, the second TD calls the first TD,
which again updates the second TD’s configuration. This
process repeats as often as necessary.
READY
WRITE
DATA
PSoC
CLK
®
ADDRESS Phase
5: CY8C53 Family Datasheet
Basic DMA Write Transfer without wait states
A
DATA Phase
DATA (A)
B
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