A000047 Arduino, A000047 Datasheet - Page 202

• Manufacturer Part Number: A000047
• Description: MCU, MPU & DSP Development Tools Mega2560
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000047

• Processor To Be Evaluated: ATmega2560
• Interface Type: USB, I2C, SPI
• Dimensions: 4 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega2560

20.2
20.2.1
2549M–AVR–09/10
Register Description
SPCR – SPI Control Register
• Bit 7 – SPIE: SPI Interrupt Enable
This bit causes the SPI interrupt to be executed if SPIF bit in the SPSR Register is set and the if
the Global Interrupt Enable bit in SREG is set.
• Bit 6 – SPE: SPI Enable
When the SPE bit is written to one, the SPI is enabled. This bit must be set to enable any SPI
operations.
• Bit 5 – DORD: Data Order
When the DORD bit is written to one, the LSB of the data word is transmitted first.
When the DORD bit is written to zero, the MSB of the data word is transmitted first.
• Bit 4 – MSTR: Master/Slave Select
This bit selects Master SPI mode when written to one, and Slave SPI mode when written logic
zero. If SS is configured as an input and is driven low while MSTR is set, MSTR will be cleared,
and SPIF in SPSR will become set. The user will then have to set MSTR to re-enable SPI Mas-
ter mode.
• Bit 3 – CPOL: Clock Polarity
When this bit is written to one, SCK is high when idle. When CPOL is written to zero, SCK is low
when idle. Refer to
CPOL functionality is summarized in
Table 20-3.
• Bit 2 – CPHA: Clock Phase
The settings of the Clock Phase bit (CPHA) determine if data is sampled on the leading (first) or
trailing (last) edge of SCK. Refer to
example. The CPOL functionality is summarized in
Table 20-4.
Bit
0x2C (0x4C)
Read/Write
Initial Value
CPOL
CPHA
CPOL Functionality
CPHA Functionality
0
1
0
1
SPIE
R/W
7
0
Figure 20-3 on page 201
SPE
R/W
6
0
ATmega640/1280/1281/2560/2561
DORD
R/W
Figure 20-3 on page 201
5
0
Table
Leading Edge
Leading Edge
MSTR
Sample
Falling
20-3.
Rising
R/W
Setup
4
0
and
Figure 20-4 on page 201
Table
CPOL
R/W
3
0
20-4.
and
CPHA
R/W
2
0
Figure 20-4 on page 201
SPR1
R/W
1
0
Trailing Edge
Trailing Edge
Sample
for an example. The
Falling
Rising
Setup
SPR0
R/W
0
0
SPCR
for an
202