ADSP-214xx SHARC Processor Hardware Reference 23-7
System Design
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 SHARC processor and a host processor.
External Host
In an AVR (audio-video receiver) system, a host microcontroller may
communicate with the 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 a SHARC as shown in Figure 23-2. In this
case, the host implements the SPI protocol on the port pins.
Processor Booting
When a processor is initially powered up, its internal SRAM is undefined.
Before actual program execution can begin, the application must be
loaded from an external non-volatile source such as flash memory or a host
processor. This process is known as bootstrap loading or booting and is
automatically performed by the processor after power-up or after a soft-
ware reset.
Figure 23-2. Example System Interface With an External Host
SPI
PORT
RUNRSTIN
ADSP-2146x
SPI OR
PORT PINS
OPEN-DRAIN
HOST
PROCESSOR
Use an external pull-up
if host pin does not have
an external pull-up
V
DD
10 k:
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