Rabbit Rabbit 4000, User Manual

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100 Rabbit 4000 Microprocessor User’s Manual
12.1.2 Registers
12.2 Dependencies
12.2.1 I/O Pins
Parallel Port E uses the pins PE0 through PE7. These pins can be used individually as data
inputs or outputs; as serial port transmit and receive for Serial Ports E and F; as clocks for
Serial Ports C–F; as external I/O strobes; as outputs for the PWM and Timer C peripher-
als; as the upper address bits A[23:20]; or as the Ethernet clock and status LEDs for the
on-chip network peripheral. The input capture peripheral can also watch pins PE7, PE5,
PE3, and PE1. There is also an option to provide the slave port chip select on PE7.
All pins are set as inputs on startup.
The individual bits can be set to be open-drain via PEDCR.
See the associated peripheral chapters for details on how they use Parallel Port E.
12.2.2 Clocks
All outputs on Parallel Port E are clocked by the peripheral clock unless changed in PECR,
where the option of updating the Parallel Port E pins can be synchronized to the output of
Timer A1, Timer B1, or Timer B2.
Register Name Mnemonic I/O Address R/W Reset
Port E Data Register PEDR 0x0070 R/W xxxxxxxx
Port E Alternate Low Register PEALR 0x0072 R/W 00000000
Port E Alternate High Register PEAHR 0x0073 R/W 00000000
Port E Control Register PECR 0x0074 R/W xx00xx00
Port E Function Register PEFR 0x0075 R/W 00000000
Port E Drive Control Register PEDCR 0x0076 R/W 00000000
Port E Data Direction Register PEDDR 0x0077 R/W 00000000
Port E Bit 0 Register PEB0R 0x0078 W xxxxxxxx
Port E Bit 1 Register PEB1R 0x0079 W xxxxxxxx
Port E Bit 2 Register PEB2R 0x007A W xxxxxxxx
Port E Bit 3 Register PEB3R 0x007B W xxxxxxxx
Port E Bit 4 Register PEB4R 0x007C W xxxxxxxx
Port E Bit 5 Register PEB5R 0x007D W xxxxxxxx
Port E Bit 6 Register PEB6R 0x007E W xxxxxxxx
Port E Bit 7 Register PEB7R 0x007F W xxxxxxxx