AT43USB326-AU Atmel, AT43USB326-AU Datasheet - Page 35

• Manufacturer Part Number: AT43USB326-AU
• Description: IC USB KEYBOARD CTRLR 48LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB326-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: Mask ROM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: USB
• Number Of I /o: 32
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Sleep Modes
Power Down Mode
3313D–USB–04/06
Stack Pointer Register – SP
The Stack Pointer points to the data SRAM stack area where the Subroutine and Interrupt
Stacks are located. This Stack space in the data SRAM must be defined by the program
before any subroutine calls are executed or interrupts are enabled. The stack pointer must be
set to point above $60. The Stack Pointer is decremented by one when data is pushed onto
the Stack with the PUSH instruction, and it is decremented by two when an address is pushed
onto the Stack with subroutine calls and interrupts. The Stack Pointer is incremented by one
when data is popped from the Stack with the POP instruction and it is incremented by two
when an address is popped from the Stack with return from subroutine RET or return from
interrupt RETI.
To enter the sleep modes, the SE bit in MCUCR must be set (one) and a SLEEP instruction
must be executed. If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU
awakes, executes the interrupt routine, and resumes execution from the instruction following
SLEEP. The contents of the register file, SRAM and I/O memory are unaltered. If a reset
occurs during sleep mode, the MCU wakes up and executes from the Reset vector.
When the SM bit is set (one), the SLEEP instruction forces the MCU into the Power Down
Mode. In this mode, the external oscillator is stopped, while the external interrupts continue
operating. Only an external reset, an external level interrupt on INT0 or INT1, can wake up the
MCU.
Note that when a level triggered interrupt is used for wake-up from power down, the low level
must be held for a time longer than the reset delay time-out period t
will fail to wake up.
Read/Write
Initial Value
$3D ($5D)
$3E ($5E)
Bit
R/W
R/W
SP7
15
7
0
0
I
R/W
R/W
SP6
14
6
0
0
T
R/W
R/W
SP5
13
H
5
0
0
R/W
R/W
SP4
12
4
0
0
S
R/W
R/W
SP3
11
3
0
0
V
R/W
R/W
SP2
10
N
2
0
0
TOUT
AT43USB326
R/W
R/W
. Otherwise, the MCU
SP1
9
1
0
0
Z
R/W
R/W
SP0
8
0
0
0
C
SPH
SPL
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