ATA5773-DK1 Atmel, ATA5773-DK1 Datasheet - Page 18

• Manufacturer Part Number: ATA5773-DK1
• Description: BOARD XMITTER FOR ATA5773 315MHZ
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATA5773-DK1

• Frequency: 315MHz
• Maximum Frequency: 315 MHz
• Supply Voltage (max): 4 V
• Supply Voltage (min): 2 V
• Supply Current: 9 mA
• Product: RF Development Tools
• For Use With/related Products: ATA5773
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.7.6
4.7.6.1
18
Atmel ATA5771/73/74
Stack Pointer
SPH and SPL – Stack Pointer High and Low
Figure 4-4.
In the different addressing modes these address registers have functions as fixed displace-
ment, 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 0x60. 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.
The Atmel AVR
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.
X-register
Y-register
Z-register
Bit
0x3E (0x5E)
0x3D (0x5D)
Read/Write
Initial Value
The X-, Y-, and Z-registers
®
SP15
SP7
R/W
R/W
15
7
0
0
Stack Pointer is implemented as two 8-bit registers in the I/O space. The
15
7
R27 (0x1B)
15
7
R29 (0x1D)
15
7
R31 (0x1F)
SP14
SP6
R/W
R/W
14
6
0
0
SP13
SP5
R/W
R/W
13
5
0
0
XH
YH
ZH
0
SP12
R/W
R/W
SP4
12
4
0
0
SP11
SP3
R/W
R/W
11
3
0
0
0
0
7
R26 (0x1A)
7
R28 (0x1C)
7
R30 (0x1E)
SP10
R/W
SP2
R/W
10
2
0
0
SP9
SP1
R/W
R/W
9
1
0
0
XL
YL
ZL
0
9137E–RKE–12/10
SP8
SP0
R/W
R/W
8
0
0
0
SPH
SPL
0
0
0
0
0