ATMEGA16U4-AU Atmel, ATMEGA16U4-AU Datasheet - Page 183

• Manufacturer Part Number: ATMEGA16U4-AU
• Description: MCU AVR 16K FLASH USB 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA16U4-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 26
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Processor Series: ATMEGA16x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1.25 KB
• Interface Type: SPI, TWI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 26
• Number Of Timers: 5
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 12 Channel
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

17.1.4
7766F–AVR–11/10
SPI Status Register – SPSR
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 17-2.
• 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 17-3.
• 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 the following table:
Table 17-4.
Bit
Read/Write
Initial Value
SPI2X
0
0
0
0
1
1
1
1
CPOL
CPHA
0
1
0
1
7
SPIF
R
0
CPOL Functionality
CPHA Functionality
Relationship Between SCK and the Oscillator Frequency
Figure 17-3
6
WCOL
R
0
SPR1
0
0
1
1
0
0
1
1
5
–
R
0
and
Leading Edge
Leading Edge
Figure 17-4
Figure 17-3
4
–
R
0
Sample
Rising
Falling
Setup
SPR0
0
1
0
1
0
1
0
1
3
–
R
0
for an example. The CPOL functionality is sum-
and
SCK Frequency
f
f
f
f
f
f
f
f
osc
osc
osc
osc
osc
osc
osc
osc
2
–
R
0
Figure 17-4
/
/
/
/
/
/
/
/
4
16
64
128
2
8
32
64
1
–
R
0
ATmega16/32U4
Trailing Edge
Trailing Edge
for an example. The CPOL
Sample
Falling
Rising
Setup
0
SPI2X
R/W
0
SPSR
osc
183
is