ATMEGA88-20PU Atmel, ATMEGA88-20PU Datasheet - Page 141

IC AVR MCU 8K 20MHZ 5V 28DIP

ATMEGA88-20PU

Manufacturer Part Number
ATMEGA88-20PU
Description
IC AVR MCU 8K 20MHZ 5V 28DIP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA88-20PU

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)
Cpu Family
ATmega
Device Core
AVR
Device Core Size
8b
Frequency (max)
20MHz
Interface Type
SPI/TWI/USART
Total Internal Ram Size
1KB
# I/os (max)
23
Number Of Timers - General Purpose
3
Operating Supply Voltage (typ)
3.3/5V
Operating Supply Voltage (max)
5.5V
Operating Supply Voltage (min)
2.7V
On-chip Adc
6-chx10-bit
Instruction Set Architecture
RISC
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Mounting
Through Hole
Pin Count
28
Package Type
PDIP
Processor Series
ATMEGA8x
Core
AVR8
Data Bus Width
8 bit
Data Ram Size
1 KB
Maximum Clock Frequency
20 MHz
Number Of Programmable I/os
23
Number Of Timers
3
Operating Supply Voltage
2.7 V to 5.5 V
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, ATAVRTS2080A, ATASTK512-EK1-IND
Minimum Operating Temperature
- 40 C
Package
28PDIP
Family Name
ATmega
Maximum Speed
20 MHz
For Use With
ATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATAVRISP2 - PROGRAMMER AVR IN SYSTEM
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
17.5
2545S–AVR–07/10
Output Compare Unit
Figure 17-2. Counter Unit Block Diagram
Signal description (internal signals):
Depending on the mode of operation used, the counter is cleared, incremented, or decremented
at each timer clock (clk
selected by the Clock Select bits (CS22:0). When no clock source is selected (CS22:0 = 0) the
timer is stopped. However, the TCNT2 value can be accessed by the CPU, regardless of
whether clk
count operations.
The counting sequence is determined by the setting of the WGM21 and WGM20 bits located in
the Timer/Counter Control Register (TCCR2A) and the WGM22 located in the Timer/Counter
Control Register B (TCCR2B). There are close connections between how the counter behaves
(counts) and how waveforms are generated on the Output Compare outputs OC2A and OC2B.
For more details about advanced counting sequences and waveform generation, see
Operation” on page
The Timer/Counter Overflow Flag (TOV2) is set according to the mode of operation selected by
the WGM22:0 bits. TOV2 can be used for generating a CPU interrupt.
The 8-bit comparator continuously compares TCNT2 with the Output Compare Register
(OCR2A and OCR2B). Whenever TCNT2 equals OCR2A or OCR2B, the comparator signals a
match. A match will set the Output Compare Flag (OCF2A or OCF2B) at the next timer clock
cycle. If the corresponding interrupt is enabled, the Output Compare Flag generates an Output
Compare interrupt. The Output Compare Flag is automatically cleared when the interrupt is exe-
cuted. Alternatively, the Output Compare Flag can be cleared by software by writing a logical
one to its I/O bit location. The Waveform Generator uses the match signal to generate an output
according to operating mode set by the WGM22:0 bits and Compare Output mode (COM2x1:0)
bits. The max and bottom signals are used by the Waveform Generator for handling the special
cases of the extreme values in some modes of operation
Figure 17-3
count
direction
clear
clk
top
bottom
Tn
T2
shows a block diagram of the Output Compare unit.
DATA BUS
is present or not. A CPU write overrides (has priority over) all counter clear or
TCNTn
144.
T2
). clk
Increment or decrement TCNT2 by 1.
Selects between increment and decrement.
Clear TCNT2 (set all bits to zero).
Timer/Counter clock, referred to as clk
Signalizes that TCNT2 has reached maximum value.
Signalizes that TCNT2 has reached minimum value (zero).
T2
direction
can be generated from an external or internal clock source,
count
clear
bottom
Control Logic
top
TOVn
(Int.Req.)
clk
Tn
Prescaler
(“Modes of Operation” on page
ATmega48/88/168
T2
in the following.
Oscillator
T/C
clk
I/O
TOSC2
TOSC1
“Modes of
144).
141

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