ATtiny87 Atmel Corporation, ATtiny87 Datasheet - Page 11
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ATtiny87
Manufacturer Part Number
ATtiny87
Description
Manufacturer
Atmel Corporation
Specifications of ATtiny87
Flash (kbytes)
8 Kbytes
Pin Count
20
Max. Operating Frequency
16 MHz
Cpu
8-bit AVR
Hardware Qtouch Acquisition
No
Max I/o Pins
16
Ext Interrupts
16
Usb Speed
No
Usb Interface
No
Spi
2
Twi (i2c)
1
Uart
1
Lin
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
11
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
Yes
Crypto Engine
No
Sram (kbytes)
0.5
Eeprom (bytes)
512
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
2
Output Compare Channels
3
Input Capture Channels
1
Pwm Channels
9
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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Company
Part Number
Manufacturer
Quantity
Price
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12 127
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20 000
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2.5
2.5.1
8265B–AVR–09/10
Stack Pointer
SPH and SPL – Stack Pointer Register
Figure 2-3.
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 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
0x3E (0x5E)
0x3D (0x5D)
Read/Write
Initial Value
SP15
SP7
R/W
R/W
The X-, Y-, and Z-registers
15
7
15
7
R27 (0x1B)
15
7
R29 (0x1D)
15
7
R31 (0x1F)
SP14
SP6
R/W
R/W
14
6
ISRAM end (See
SP13
R/W
R/W
SP5
13
5
XH
YH
ZH
0
SP12
SP4
R/W
R/W
12
4
Table 3-1 on page
SP11
SP3
R/W
R/W
11
3
0
0
7
R26 (0x1A)
7
R28 (0x1C)
7
R30 (0x1E)
SP10
R/W
SP2
R/W
10
2
15)
R/W
R/W
SP9
SP1
9
1
XL
YL
ZL
SP8
SP0
R/W
R/W
8
0
SPH
SPL
11
0
0
0
0
0
0