AT90USB646-MU Atmel, AT90USB646-MU Datasheet - Page 14

• Manufacturer Part Number: AT90USB646-MU
• Description: IC AVR MCU 64K 64QFN
• Manufacturer: Atmel
• Series: AVR® 90USBr

Specifications of AT90USB646-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART, USB, USB OTG
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 48
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VQFN Exposed Pad, 64-HVQFN, 64-SQFN, 64-DHVQFN
• Processor Series: 90USB
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, TWI, USART, USB
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 48
• Number Of Timers: 4
• Operating Supply Voltage: 5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Cpu Family: AT90
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 20MHz
• Total Internal Ram Size: 4KB
• # I/os (max): 48
• Number Of Timers - General Purpose: 4
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 64
• Package Type: QFN EP
• For Use With: ATSTK600-TQFP64 - STK600 SOCKET/ADAPTER 64-TQFP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATSTK525 - KIT STARTER FOR AT90USBAT90USBKEY2 - KIT DEMO FOR AT90USB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AT90USB646-16MU; AT90USB646-16MU

4.6
14
Stack Pointer
AT90USB64/128
Figure 4-3.
In the different addressing modes these address registers have functions as fixed displacement,
automatic increment, and automatic decrement (see the instruction set reference for details).
The Stack is mainly used for storing temporary data, for storing local variables and for storing
return addresses after interrupts and subroutine calls. The Stack Pointer Register always points
to the top of the Stack. Note that the Stack is implemented as growing from higher memory loca-
tions to lower memory locations. This implies that a Stack PUSH command decreases the Stack
Pointer.
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 0x0100. The initial value of the stack pointer is the last address of the internal
SRAM. The Stack Pointer is decremented by one when data is pushed onto the Stack with the
PUSH instruction, and it is decremented by three when the return address is pushed onto the
Stack with subroutine call or interrupt. The Stack Pointer is incremented by one when data is
popped from the Stack with the POP instruction, and it is incremented by three when data is
popped from the Stack with return from subroutine RET or return from interrupt RETI.
The AVR Stack Pointer is implemented as two 8-bit registers in the I/O space. The number of
bits actually used is implementation dependent. Note that the data space in some implementa-
tions of the AVR architecture is so small that only SPL is needed. In this case, the SPH Register
will not be present.
X-register
Y-register
Z-register
Bit
Read/Write
Initial Value
The X-, Y-, and Z-registers
15
SP15
SP7
7
R/W
R/W
0
1
15
7
R27 (0x1B)
15
7
R29 (0x1D)
15
7
R31 (0x1F)
14
SP14
SP6
6
R/W
0
1
R/W
13
SP13
SP5
5
R/W
R/W
1
1
XH
YH
ZH
0
0
12
SP12
SP4
4
R/W
R/W
1
11
SP11
SP3
3
R/W
R/W
0
1
0
0
7
R26 (0x1A)
7
R28 (0x1C)
7
R30 (0x1E)
10
SP10
SP2
2
R/W
R/W
0
1
9
SP9
SP1
1
R/W
R/W
0
1
XL
YL
ZL
0
8
SP8
SP0
0
R/W
R/W
0
1
7593K–AVR–11/09
SPH
SPL
0
0
0
0
0