AT32UC3L064_1 ATMEL [ATMEL Corporation], AT32UC3L064_1 Datasheet - Page 716

• Manufacturer Part Number: AT32UC3L064_1
• Description: AVR32 32-bit Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

30.5.1
30.5.2
30.5.3
30.5.4
30.5.5
30.5.6
30.6
30.6.1
32099A–AVR32–06/09
Functional Description
I/O Lines
Power Management
Clocks
Interrupts
Debug Operation
External Components
How to Initialize The Module
The pin used by AW is multiplexed with the RESET_N pin. The reset functionality is the default
function of this pin. To enable the aWire functionality on the RESET_N pin the user must enable
the aWire UART user interface.
If the CPU enters a sleep mode that disables clocks used by the aWire UART user interface, the
aWire UART user interface will stop functioning and resume operation after the system wakes
up from sleep mode.
The aWire UART uses the internal 120 MHz RC oscillator (RC120M) as clock source for its
operation. When using the aWire UART user interface RC120M must enabled using the Clock
Request Register (see
The clock for the aWire UART user interface (CLK_AW) is generated by the Power Manager.
This clock is enabled at reset, and can be disabled in the Power Manager. It is recommended to
disable the aWire UART user interface before disabling the clock, to avoid freezing the aWire
UART user interface in an undefined state.
The aWire UART user interface interrupt request line is connected to the interrupt controller.
Using the aWire UART user interface interrupt requires the interrupt controller to be pro-
grammed first.
If the AW is used for debugging the aWire UART user interface will not be usable.
When an external debugger forces the CPU into debug mode, the aWire UART user interface
continues normal operation. If the aWire UART user interface is configured in a way that
requires it to be periodically serviced by the CPU through interrupts or similar, improper opera-
tion or data loss may result during debugging.
The AW needs an external pullup on the RESET_N pin to ensure that the pin is pulled up when
the bus is not driven.
The aWire UART user interface can be used as a spare Asynchronous Receiver or Transmitter
when AW is not used for debugging.
To initialize the aWire UART user interface the user must first enable the clock by writing a one
to the Clock Enable bit in the Clock Request Register (CLKR.CLKEN) and wait for the Clock
Enable bit in the Status Register (SR.CENABLED) to be set. After doing this either receive,
transmit or receive with resync must be selected by writing the corresponding value into the
Mode field of the Control (CTRL.MODE) Register. Due to the RC120M being asynchronous the
with the system clock values must be allowed to propagate in the system. During this time the
aWire master will set the Busy bit in the Status Register (SR.BUSY).
Section
30.6.1).
AT32UC3L
716