at91cap7e ATMEL Corporation, at91cap7e Datasheet - Page 98

• Manufacturer Part Number: at91cap7e
• Description: Customizable Microcontroller
• Manufacturer: ATMEL Corporation

18.6
18.6.1
Table 18-2.
98
Offset
0x00
0x04
0x08
Shutdown Controller (SHDWC) User Interface
AT91CAP7E
Register Mapping
Shutdown Controller (SHDWC) Registers
Register
Shutdown Control Register
Shutdown Mode Register
Shutdown Status Register
A typical application connects the pin
viding the main power supplies of the system, and especially VDDCORE and/or VDDIO. The
wake-up inputs (WKUP0) connect to any push-buttons or signal that wake up the system.
The software is able to control the pin
(SHDW_CR) with the bit SHDW at 1. The shutdown is taken into account only 2 slow clock
cycles after the write of SHDW_CR. This register is password-protected and so the value written
should contain the correct key for the command to be taken into account. As a result, the system
should be powered down.
A level change on WKUP0 is used as wake-up. Wake-up is configured in the Shutdown Mode
Register (SHDW_MR). The transition detector can be programmed to detect either a positive or
negative transition or any level change on WKUP0. The detection can also be disabled. Pro-
gramming is performed by defining WKMODE0.
Moreover, a debouncing circuit can be programmed for WKUP0. The debouncing circuit filters
pulses on WKUP0 shorter than the programmed number of 16 SLCK cycles in CPTWK0 of the
SHDW_MR register. If the programmed level change is detected on a pin, a counter starts.
When the counter reaches the value programmed in the corresponding field, CPTWK0, the
SHDN
sponding value, the counter is stopped and cleared. WAKEUP0 of the Status Register
(SHDW_SR) reports the detection of the programmed events on WKUP0 with a reset after the
read of SHDW_SR.
The Shutdown Controller can be programmed so as to activate the wake-up using the RTT
alarm (the detection of the rising edge of the RTT alarm is synchronized with SLCK). This is
done by writing the SHDW_MR register using the RTTWKEN fields. When enabled, the detec-
tion of the RTT alarm is reported in the RTTWK bit of the SHDW_SR Status register. It is reset
after the read of SHDW_SR. When using the RTT alarm to wake up the system, the user must
ensure that the RTT alarm status flag is cleared before shutting down the system. Otherwise, no
rising edge of the status flag may be detected and the wake-up fails.
pin is released. If a new input change is detected before the counter reaches the corre-
Name
SHDW_CR
SHDW_MR
SHDW_SR
SHDN
SHDN
to the shutdown input of the DC/DC Converter pro-
by writing the Shutdown Control Register
Read-Write
Write-only
Read-only
Access
0x0000_0303
0x0000_0000
Reset Value
8549A–CAP–10/08
-