ATMEGA128RFA1-ZU Atmel, ATMEGA128RFA1-ZU Datasheet - Page 13

• Manufacturer Part Number: ATMEGA128RFA1-ZU
• Description: IC AVR MCU 2.4GHZ XCEIVER 64QFN
• Manufacturer: Atmel
• Series: ATMEGAr

Specifications of ATMEGA128RFA1-ZU

• Frequency: 2.4GHz
• Data Rate - Maximum: 2Mbps
• Modulation Or Protocol: 802.15.4 Zigbee
• Applications: General Purpose
• Power - Output: 3.5dBm
• Sensitivity: -100dBm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Current - Receiving: 12.5mA
• Current - Transmitting: 14.5mA
• Data Interface: PCB, Surface Mount
• Memory Size: 128kB Flash, 4kB EEPROM, 16kB RAM
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VFQFN, Exposed Pad
• Rf Ic Case Style: QFN
• No. Of Pins: 64
• Supply Voltage Range: 1.8V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Svhc: No SVHC (15-Dec-2010)
• Rohs Compliant: Yes
• Processor Series: ATMEGA128x
• Core: AVR8
• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 128 KB
• Data Ram Size: 16 KB
• Interface Type: JTAG
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 38
• Number Of Timers: 6
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVR128RFA1-EK1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7.6 Stack Pointer
7.6.1 SPH – Stack Pointer High
8266A-MCU Wireless-12/09
Figure 7-2. The X-, Y-, Z-registers
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 locations 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 0x0200. 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 two 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
two when data is popped from the Stack with return from subroutine RET or return from
interrupt RETI.
When the FLASH memory exceeds 128Kbyte one additional cycle is required. In this
case the Stack Pointer is decremented by three when the return address is pushed onto
the Stack with subroutine call or interrupt and 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 SPL and SPH in the I/O
space. The number of bits actually used is implementation dependent. Note that the
data space in some implementations of the AVR architecture is so small that only SPL
is needed. In this case, the SPH Register will not be present.
• Bit 7:0 – SP15:8 - Stack Pointer High Byte
Bit
$3E ($5E)
Read/Write
Initial Value
SP15
RW
7
0
SP14
RW
6
0
SP13
RW
5
1
SP12
RW
4
0
SP11
RW
3
0
ATmega128RFA1
SP10
RW
2
0
SP9
RW
1
0
SP8
RW
0
1
SPH
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