XS1-L02A-QF124-I5 XMOS, XS1-L02A-QF124-I5 Datasheet - Page 22

• Manufacturer Part Number: XS1-L02A-QF124-I5
• Description: IC MPU 32BIT DUAL CORE 124QFN
• Manufacturer: XMOS

Specifications of XS1-L02A-QF124-I5

• Processor Type: XCore 32-Bit
• Speed: 500MHz
• Voltage: 0.95 V ~ 1.05 V
• Mounting Type: Surface Mount
• Package / Case: 124-TFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 880-1031

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3.6 Channel Communication
At application level, the basic communication entity is a stream of data. A stream
does not need to be limited in length, but it can be terminated after a short
number of tokens has been transmitted, and can hence act as a ”packet” in a
packet switched network. A stream is circuit switched and must be set up and
terminated. If the destination channel end is local, data is exchanged directly.
If the destination channel end is on a remote tile, the switch first transmits a
header to the other remote tile. This header sets up a circuit for the stream.
After the header is transmitted, the data-tokens and control-tokens of the stream
are transmitted. When the END token is transmitted, the switches free any re-
sources, folding up the circuit that was used for streaming the data. The END
token also returns all communication wires to a low-power state. A thread can
temporarily suspend a stream by issue a PAUSE token at any time, which frees
up the circuit and returns the communication wires to a low power state. Unlike
the END token, the PAUSE token is invisible to the receiver, and is discarded
once the final switch has freed its resources (analogous to the final switch dis-
carding the header that was sent when the stream started).
Streams can be used to stream data such as audio or video just by opening the
stream and sending volumes of data. Complex data types can be transmitted
over a stream by opening a stream, and serialising the data, interspersed with
user defined control tokens. This allows software to be constructed defensively
by using control tokens to mark known synchronisation points in the data stream.
If, at any time, the receiver were to try and input data when a control token is
available or vice versa, the thread is trapped, and the program can flag or maybe
recover from software errors.
By keeping streams short and synchronising often, streams can also be used
to exchange packets of data. The cost of setting up a stream and terminating
a stream is small, and unlike traditional packet-oriented networks, the packet
is transmitted while it is being constructed; this overlaps packet creation and
packet reception, reducing latency.
3.6.1 Application Tokens
Application tokens are defined by the compiler or application program. Four
Application Control Tokens have been predefined, which should not be used for
any other purpose:
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