ATMEGA88P-20PU Atmel, ATMEGA88P-20PU Datasheet - Page 190

• Manufacturer Part Number: ATMEGA88P-20PU
• Description: MCU AVR 8K ISP FLASH 20MHZ 28DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA88P-20PU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Processor Series: ATMEGA8x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Interface Type: I2C, SPI, USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 23
• Number Of Timers: 3
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATASTK512-EK1-IND
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 6 Channel
• Controller Family/series: AVR MEGA
• No. Of I/o's: 23
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Cpu Speed: 20MHz
• Rohs Compliant: Yes
• For Use With: ATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATAVRISP2 - PROGRAMMER AVR IN SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

19.8.3
8025L–AVR–7/10
Asynchronous Operational Range
Figure 19-7. Stop Bit Sampling and Next Start Bit Sampling
The same majority voting is done to the stop bit as done for the other bits in the frame. If the stop
bit is registered to have a logic 0 value, the Frame Error (FEn) Flag will be set.
A new high to low transition indicating the start bit of a new frame can come right after the last of
the bits used for majority voting. For Normal Speed mode, the first low level sample can be at
point marked (A) in
(B). (C) marks a stop bit of full length. The early start bit detection influences the operational
range of the Receiver.
The operational range of the Receiver is dependent on the mismatch between the received bit
rate and the internally generated baud rate. If the Transmitter is sending frames at too fast or too
slow bit rates, or the internally generated baud rate of the Receiver does not have a similar (see
Table 19-2 on page
frames to the start bit.
The following equations can be used to calculate the ratio of the incoming data rate and internal
receiver baud rate.
D
S
S
S
R
Table 19-2 on page 191
that can be tolerated. Note that Normal Speed mode has higher toleration of baud rate
variations.
F
M
slow
(U2X = 0)
(U2X = 1)
Sample
Sample
RxD
R
slow
Sum of character size and parity size (D = 5 to 10 bit)
Samples per bit. S = 16 for Normal Speed mode and S = 8 for Double Speed
mode.
First sample number used for majority voting. S
for Double Speed mode.
Middle sample number used for majority voting. S
S
is the ratio of the slowest incoming data rate that can be accepted in relation to the
receiver baud rate. R
accepted in relation to the receiver baud rate.
M
=
= 5 for Double Speed mode.
Figure
------------------------------------------ -
S 1
191) base frequency, the Receiver will not be able to synchronize the
–
1
1
(
and
D
+
2
19-7. For Double Speed mode the first low level must be delayed to
+
D S ⋅
1
Table 19-3 on page 191
)S
3
2
+
S
4
F
fast
5
3
is the ratio of the fastest incoming data rate that can be
6
7
4
8
STOP 1
9
5
ATmega48P/88P/168P
list the maximum receiver baud rate error
10
0/1
(A)
6
R
0/1
F
fast
= 8 for normal speed and S
M
0/1
0/1
(B)
= 9 for normal speed and
=
-----------------------------------
(
D
(
+
D
1
+
)S
2
)S
+
(C)
S
M
F
190
= 4