Clock Derivation
14-24 ADSP-21368 SHARC Processor Hardware Reference
There are several possible methods that can be used to implement running
reset. The following illustrates one example of a running reset implemen-
tation involving an ADSP-2137x processor and a host processor.
External Host
In an AVR (audio-video receiver) system, a host micro controller may
communicate with the ADSP-2137x processor using the serial peripheral
interface (SPI). Or, if no SPI pins are available on the host device, it can
use spare flag I/Os to connect with the SPI of SHARC as shown in
Figure 14-5). In this case, the host implements the SPI protocol on the
port pins.
Using the SPI protocol with additional control words and commands,
running reset can become an addition command from the host or from the
ADSP-2137x processor as described in the following procedure.
1. The host initiates a running reset by informing the processor over
the command interface.
Figure 14-5. Example System Interface With an External Host
RUNRSTIN
+Vdd
10 k
Ω
ADSP-2137x
SPI
PORT
SPI OR
PORT PINS
Open
Drain
Use an external pull-up
if host pin does not have
an internal pull-up
Host Processor
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