Programmable I/O Signals
Am186™CC/CH/CU Microcontrollers User’s Manual
9-7
9.5.6
Hardware-Related Considerations
Choose your PIOs wisely. The following PIO signals are multiplexed with alternate signals
that may be used by emulators: PIO8, PIO15, PIO33, PIO34, and PIO35. Consider any
emulator requirements for the alternate signals before using these pins as PIOs. For more
information, see Chapter 4, “Emulator Support.”
9.5.7
Software-Related Considerations
■
The PIO Set and PIO Clear registers provide an efficient, nondestructive means to modify
specific data values for the PIOs. Previous Am186 devices required the user to perform
a read-mask-modify-write approach when modifying PIO data values (and preserving
the values of other bits in the register). With the PIO Set and PIO Clear registers, specific
bits can be set or cleared in a single write.
■
When configuring PIOs, modify only the bits relevant to your application by reading the
existing register value, masking the bits needed, and writing the register.
9.5.8
Comparison to Other Devices
■
The PIO registers are similar to previous Am186 controller implementations. The PIO
Mode, PIO Direction, and PIO Data registers behave similarly; the PIO Set and PIO
Clear registers have been added.
■
The Am186CC/CH/CU microcontrollers offer 48 PIOs rather than the 32 offered in other
Am186 implementations, and these PIOs have different pin assignments.
9.6
INITIALIZATION
On both an external and internal reset, the following occurs:
■
The PIOMODE0 register defaults to 0000h, the PIODIR0 register to 1EFFh, PIOMODE1
to 0000h, PIODIR1 to 9FFFh, PIOMODE2 to 0000h, and PIODIR2 to FFF1h. This
defaults the PIOs to various configurations as shown in Table 9-1 on page 9-3. (PIO8,
PIO13, PIO14, PIO15, PIO29, PIO30, PIO33, PIO34, and PIO35 default to their alternate
operation. The remaining PIOs default to the PIO function.) System initialization code
must reconfigure PIOs as required.
■
The PIOSETx and PIOCLRx registers default to 0000h.
■
The PIODATAx registers default to values dependent on the system configuration. For
more information, see the
Am186™CC/CH/CU Microcontrollers Register Set Manual,
order #21916.
Содержание Am186 CC
Страница 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Страница 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Страница 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Страница 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Страница 39: ...Architectural Overview Am186 CC CH CU Microcontrollers User s Manual 1 15 Figure 1 6 32 Channel Linecard CH CC...
Страница 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Страница 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Страница 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Страница 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Страница 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...