Rabbit BL2020, Руководство пользователя

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26 Wildcat (BL2000)
Alternate Uses of the Serial Programming Port
All three clocked Serial Port A signals are available as
•
a synchronous serial port
•
an asynchronous serial port, with the clock line usable as a general CMOS input
The serial programming port may also be used as a serial port via the
DIAG
connector on
the serial programming cable.
In addition to Serial Port A, the Rabbit 2000 startup-mode (SMODE0, SMODE1), status,
and reset pins are available on the serial programming port.
The two startup mode pins determine what happens after a reset—the Rabbit 2000 is
either cold-booted or the program begins executing at address 0x0000. These two
SMODE pins can be used as general inputs once the cold boot is complete.
The status pin is used by Dynamic C to determine whether a Rabbit microprocessor is
present. The status output has three different programmable functions:
1. It can be driven low on the first op code fetch cycle.
2. It can be driven low during an interrupt acknowledge cycle.
3. It can also serve as a general-purpose output.
The /RESET_IN pin is an external input that is used to reset the Rabbit 2000 and the
onboard peripheral circuits on the RabbitCore module. The serial programming port can be
used to force a hard reset on the RabbitCore module by asserting the /RESET_IN signal.
Refer to the Rabbit 2000 Microprocessor User’s Manual for more information.