ATmega32A Atmel Corporation, ATmega32A Datasheet - Page 145
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ATmega32A
Manufacturer Part Number
ATmega32A
Description
Manufacturer
Atmel Corporation
Specifications of ATmega32A
Flash (kbytes)
32 Kbytes
Pin Count
44
Max. Operating Frequency
16 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
32
Ext Interrupts
3
Usb Speed
No
Usb Interface
No
Spi
1
Twi (i2c)
1
Uart
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
2
Eeprom (bytes)
1024
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
2.7 to 5.5
Operating Voltage (vcc)
2.7 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
3
Output Compare Channels
4
Input Capture Channels
1
Pwm Channels
4
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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18.3.4
18.3.5
18.4
8155C–AVR–02/11
Data Modes
SPSR – SPI Status Register
SPDR – SPI Data Register
• Bit 7 – SPIF: SPI Interrupt Flag
When a serial transfer is complete, the SPIF Flag is set. An interrupt is generated if SPIE in
SPCR is set and global interrupts are enabled. If SS is an input and is driven low when the SPI is
in Master mode, this will also set the SPIF Flag. SPIF is cleared by hardware when executing the
corresponding interrupt handling vector. Alternatively, the SPIF bit is cleared by first reading the
SPI Status Register with SPIF set, then accessing the SPI Data Register (SPDR).
• Bit 6 – WCOL: Write COLlision Flag
The WCOL bit is set if the SPI Data Register (SPDR) is written during a data transfer. The
WCOL bit (and the SPIF bit) are cleared by first reading the SPI Status Register with WCOL set,
and then accessing the SPI Data Register.
• Bit 5:1 – Reserved Bits
These bits are reserved bits in the ATmega32A and will always read as zero.
• Bit 0 – SPI2X: Double SPI Speed Bit
When this bit is written logic one the SPI speed (SCK Frequency) will be doubled when the SPI
is in Master mode (see
clock periods. When the SPI is configured as Slave, the SPI is only guaranteed to work at f
or lower.
The SPI interface on the ATmega32A is also used for program memory and EEPROM down-
loading or uploading. See
The SPI Data Register is a read/write register used for data transfer between the Register File
and the SPI Shift Register. Writing to the register initiates data transmission. Reading the regis-
ter causes the Shift Register Receive buffer to be read.
There are four combinations of SCK phase and polarity with respect to serial data, which are
determined by control bits CPHA and CPOL. The SPI data transfer formats are shown in
18-3
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
and
Figure
MSB
SPIF
R/W
18-4. Data bits are shifted out and latched in on opposite edges of the SCK sig-
X
R
7
7
0
Table
WCOL
R/W
page 279
6
X
R
6
0
18-4). This means that the minimum SCK period will be two CPU
R/W
X
5
R
5
–
0
for SPI Serial Programming and Verification.
R/W
4
X
R
4
–
0
R/W
X
3
R
3
–
0
R/W
X
2
R
2
–
0
R/W
1
X
R
1
–
0
ATmega32A
SPI2X
LSB
R/W
R/W
X
0
0
0
Undefined
SPDR
SPSR
Figure
osc
145
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