ATmega1280 Atmel Corporation, ATmega1280 Datasheet - Page 203

• Manufacturer Part Number: ATmega1280
• Manufacturer: Atmel Corporation

Specifications of ATmega1280

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 86
• Ext Interrupts: 32
• Usb Speed: No
• Usb Interface: No
• Spi: 5
• Twi (i2c): 1
• Uart: 4
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• 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: 6
• Output Compare Channels: 16
• Input Capture Channels: 4
• Pwm Channels: 15
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

21.2.2
2549N–AVR–05/11
SPSR – SPI Status Register
• Bits 1, 0 – SPR1, SPR0: SPI Clock Rate Select 1 and 0
These two bits control the SCK rate of the device configured as a Master. SPR1 and SPR0 have
no effect on the Slave. The relationship between SCK and the Oscillator Clock frequency f
shown in
Table 21-5.
• 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 – Res: Reserved Bits
These bits are reserved bits 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 ATmega640/1280/1281/2560/2561 is also used for program memory
and EEPROM downloading or uploading. See
gramming and verification.
Bit
0x2D (0x4D)
Read/Write
Initial Value
SPI2X
0
0
0
0
1
1
1
1
Table
Relationship Between SCK and the Oscillator Frequency
21-5.
SPIF
7
R
0
Table
WCOL
SPR1
6
R
0
0
0
1
1
0
0
1
1
21-5). This means that the minimum SCK period will be two CPU
ATmega640/1280/1281/2560/2561
R
5
–
0
SPR0
R
4
–
0
0
1
0
1
0
1
0
1
“Serial Downloading” on page 349
R
3
–
0
R
2
–
0
SCK Frequency
R
1
–
0
f
f
f
osc
f
f
f
osc
osc
f
f
osc
osc
osc
osc
osc
/
/
/
/
/
128
/
/
/
16
64
32
64
4
2
8
SPI2X
R/W
0
0
for serial pro-
SPSR
osc
osc
203
/4
is