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Chapter 6: MPC8270 Parallel I/O Ports
significant flexibility, many dedicated peripheral functions are multiplexed onto the ports. The
functions are grouped to maximize the pin's usefulness in the greatest number of MPC8270
applications. Refer to the MPC8270 PowerQUICC II User’s Manual for more information on the
various peripheral setups. See “Freescale MPC8270 PowerQUICC II Processor,” on page 117
for a link to this manual.
Any port pins that do not have a dedicated function in the AMC335 configuration should be
configured as an output and set to either a high or low. This eliminates the potential for an
unterminated input that could create severe current draw and electrical noise within the part if it
were floating.
Serial Management Controllers
The MPC8270 features two general-purpose serial management controllers (SMC1 and
SMC2) that may be used as general-purpose RS232C communications interfaces. The two
SMCs are full-duplex ports that can be configured independently to support one of three
operating or modes:
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Universal Asynchronous Receiver/Transmitter (UART)
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Transparent
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General Circuit Interface (GCI)
The AMC335 is designed to support UART operation on two ports (one console and one
MMC). The default point for console access is through the dual VHDCI connector when the
module is installed in a system. An additional connection is available through a three-pin
header, located on the top side of the AMC335, providing connectivity to the SMC, which is
configured as the console serial port.
The console serial port can be used to provide a debug, monitor, or download function. The
console serial port also has the ability to generate a PQ_HRESET_N if it receives two RS232
break signals that each lasts for longer than 13 ms. If a break and a character is received the
console focus shifts from the MCP8270 to the MMC. The logic that watches the console
receive line is located in the control logic PLD. The reset-on-break detect can be enabled by
setting the Break Detect Enable Switch (SW3-3) to ON. Setting the switch to OFF disables the
feature. See “SW3-3 (Break Detect Enable),” on page 40 for more information.
Note: The reset-on-break detect can still be enabled with a software settable PAL register bit.
The secondary Serial I/O channel is used to communicate with the MMC.
MPC8270 Parallel Port Pin Assignments
The MPC8270 parallel ports are configured to support serial I/O, modem control, interrupts,
and other module-required functions. The program settings for the parallel port pins can be
found in the files init.inc and hardware.c. Individual pin assignments for each port are shown
in the following tables:
96
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Table 6-1, “MPC8270 Port A Pin Assignments,” on page 97
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Table 6-2, “MPC8270 Port B Pin Assignments,” on page 98
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Table 6-3, “MPC8270 Port C Pin Assignments,” on page 99
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Table 6-4, “MPC8270 Port D Pin Assignments,” on page 100