ATMEGA48V_11 ATMEL [ATMEL Corporation], ATMEGA48V_11 Datasheet - Page 169

• Manufacturer Part Number: ATMEGA48V_11
• Description: 8-bit Atmel Microcontroller with 4/8/16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

19.5.2
2545T–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 19-5.
• 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 in the Atmel ATmega48/88/168 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 ATmega48/88/168 is also used for program memory and EEPROM
downloading or uploading. See
Bit
0x2D (0x4D)
Read/write
Initial value
SPI2X
0
0
0
0
1
1
1
1
Table
Relationship between SCK and the oscillator frequency.
19-5:
SPIF
R
7
0
Table
WCOL
SPR1
R
6
0
0
0
1
1
0
0
1
1
19-5). This means that the minimum SCK period will be two CPU
page 298
R
5
–
0
for serial programming and verification.
SPR0
R
4
–
0
0
1
0
1
0
1
0
1
R
3
–
0
SCK frequency
f
f
f
f
f
f
f
f
osc
osc
osc
osc
osc
osc
osc
osc
/
/
/
/
/
/
/
/
4
16
64
128
2
8
32
64
ATmega48/88/168
R
2
–
0
R
1
–
0
SPI2X
R/W
0
0
SPSR
osc
osc
169
/4
is