ata6616 ATMEL Corporation, ata6616 Datasheet - Page 170

• Manufacturer Part Number: ata6616
• Description: Microcontroller With Lin Transceiver, 5v Regulator And Watchdog
• Manufacturer: ATMEL Corporation

170
ATA6616/ATA6617 [Preliminary]
• 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
marized below:
Table 4-40.
• 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
functionality is summarized below:
Table 4-41.
• 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 clk
the following table:
Table 4-42.
SPI2X
0
0
0
0
1
1
1
1
CPOL
CPHA
CPOL Functionality
CPHA Functionality
Relationship Between SCK and the Oscillator Frequency
0
1
0
1
Figure 4-60
SPR1
0
0
1
1
0
0
1
1
and
Figure 4-61
Figure 4-60
Leading Edge
Leading Edge
Sample
Falling
Rising
Setup
SPR0
0
1
0
1
0
1
0
1
DRAFT
for an example. The CPOL functionality is sum-
and
Figure 4-61
SCK Frequency
f
f
f
f
f
f
f
f
clkio
clkio
clkio
clkio
clkio
clkio
clkio
clkio
/
/
/
/
/
/
/
/
4
16
64
128
2
8
32
64
IO
for an example. The CPOL
frequency f
Trailing Edge
Trailing Edge
Sample
Falling
Rising
Setup
clkio
9132A–AUTO–10/08
is shown in