User`s manual

User’s Manual 13
2.2.3 Programming Port
Serial Port A has special features that allow it to cold-boot the system after reset. Serial
Port A is also the port that is used for software development under Dynamic C.
The RabbitCore RCM3000 Series has a 10-pin program header labeled J3. The Rabbit
3000 startup-mode pins (SMODE0, SMODE1) are presented to the programming port so
that an externally connected device can force the RCM3000 to start up in an external boot-
strap mode. The Rabbit 3000 Microprocessor User’s Manual provides more information
related to the bootstrap mode.
The programming port is used to start the RabbitCore RCM3000 in a mode where it will
download a
program from the port and then execute the program. The programming port
transmits information to and from a PC while a program is being debugged in-circuit.
The RabbitCore RCM3000 can be reset from the programming port via the /RESET_IN line.
The Rabbit 3000 status pin is also presented to the programming port. The status pin is an
output that can be used to send a general digital signal.
The clock line for Serial Port A is presented to the programming port, which makes syn-
chronous serial communication possible.
Programming may also be initiated through the motherboard to which the RCM3000
series module is plugged in to since the Serial Port A (PC6 and PC7), SMODE0, SMODE1,
and /RESET_IN are available on headers J1 and J2 (see Table 1).
2.2.3.1 Alternate Uses of the Programming Port
The programming port may also be used as an application port with the DIAG connector
on the programming cable.
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
• two general CMOS inputs and one general CMOS output.
Two startup mode pins, SMODE0 and SMODE1, are available as general CMOS inputs
after they are read during the initial boot-up. The logic state of these two pins is very
important in determining the startup procedure after a reset.
/RES_IN is an external input used to reset the Rabbit 3000 microprocessor.
The status pin may also be used as a general CMOS output.
See Appendix E, “Programming Cable,” for more information.