Simoco Xfin Blade, Service Manual

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TECHNICAL DESCRIPTION
4.2.2.3 DSP
The DSP on the Xfin control card is a Blackfin device manufactured by Analog Devices; it
runs at speeds of up to 500 MHz. The DSP is responsible for all audio processing
including mixing, FFSK encoding/decoding, DTMF encoding/decoding, supervisory tone
generation, audio emphasis and speech processing for VOIP between Blades.
Booting
The DSP downloads the application code from the IXP Network Processor at start up and
runs the software entirely in internal memory.
RS232 Serial Interface (Rear RJ-45)
The rear of the Blade contains a standard RJ-45 Serial connection in order that an
engineer may connect a PC to the DSP via an RJ-45 to DB-9 cable. Debug commands
may then be issued to the DSP for diagnostic information.
CPLD Interface
Communications between the IXP Network Processor and the DSP are performed by
connecting the data bus on the IXP to the host interface (Lattice LC256V-75T100 CPLD)
connecting to the DSP. The IXP writes to the host interface, triggering a DMA on the DSP
to copy the data to a buffer. After a packet has been sent, the DMA on the DSP copies
data from an outgoing buffer to the host interface port that is read by the IXP. This enables
high-speed communications without impacting the performance of the DSP.