AT90PWM3B-16SU Atmel, AT90PWM3B-16SU Datasheet - Page 186

• Manufacturer Part Number: AT90PWM3B-16SU
• Description: IC MCU AVR RISC 8K FLASH 32-SOIC
• Manufacturer: Atmel
• Series: AVR® 90PWM Lightingr

Specifications of AT90PWM3B-16SU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 27
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 11x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 32-SOIC (7.5mm Width)
• Processor Series: AT90PWMx
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 512 B
• Interface Type: SPI/USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 27
• Number Of Timers: 2
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATAVRFBKIT, ATAVRISP2
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 11-ch x 10-bit
• On-chip Dac: 1-chx10-bit
• Controller Family/series: AVR PWM
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 512Byte
• Cpu Speed: 16MHz
• Rohs Compliant: Yes
• For Use With: ATSTK600-SOIC - STK600 SOCKET/ADAPTER FOR SOIC770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRMC200 - KIT EVAL FOR AT90PWM3 ASYNCATAVRFBKIT - KIT DEMO BALLAST FOR AT90PWM2ATAVRISP2 - PROGRAMMER AVR IN SYSTEMATSTK520 - ADAPTER KIT FOR 90PWM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

18.3.2
18.3.3
186
AT90PWM2/2B/3/3B
Double Speed Operation (U2X)
External Clock
Table 70
the UBRR value for each mode of operation using an internally generated clock source.
Table 70. Equations for Calculating Baud Rate Register Setting
Note:
Some examples of UBRR values for some system clock frequencies are found in
page
The transfer rate can be doubled by setting the U2X bit in UCSRA. Setting this bit only has effect
for the asynchronous operation. Set this bit to zero when using synchronous operation.
Setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling
the transfer rate for asynchronous communication. Note however that the Receiver will in this
case only use half the number of samples (reduced from 16 to 8) for data sampling and clock
recovery, and therefore a more accurate baud rate setting and system clock are required when
this mode is used. For the Transmitter, there are no downsides.
External clocking is used by the synchronous slave modes of operation. The description in this
section refers to
External clock input from the XCK pin is sampled by a synchronization register to minimize the
chance of meta-stability. The output from the synchronization register must then pass through
an edge detector before it can be used by the Transmitter and Receiver. This process intro-
duces a two CPU clock period delay and therefore the maximum external XCK clock frequency
is limited by the following equation:
Note that
to add some margin to avoid possible loss of data due to frequency variations.
Operating Mode
Asynchronous Normal mode
(U2X = 0)
Asynchronous Double Speed
mode (U2X = 1)
Synchronous Master mode
BAUD Baud rate (in bits per second, bps).
f
UBRR Contents of the UBRRH and UBRRL Registers, (0-4095).
clk
207).
io
1. The baud rate is defined to be the transfer rate in bit per second (bps)
contains equations for calculating the baud rate (in bits per second) and for calculating
f
System I/O Clock frequency.
clk
io
depends on the stability of the system clock source. It is therefore recommended
Figure 18-2
for details.
Equation for Calculating Baud
BAUD
BAUD
BAUD
=
=
=
----------------------------------------- -
16 UBRRn
Rate
-------------------------------------- -
8 UBRRn
-------------------------------------- -
2 UBRRn
f
XCKn
(
(
(
(1)
f
f
f
CLKio
CLKio
CLKio
<
f
--------------- -
CLKio
4
+
+
+
1
1
1
)
)
)
Equation for Calculating UBRR
UBRRn
UBRRn
UBRRn
=
Value
=
=
----------------------- - 1
16BAUD
------------------- - 1
8BAUD
------------------- - 1
2BAUD
f
f
f
CLKio
CLKio
CLKio
4317H–AVR–12/06
Table 9
–
–
–
(see