ATMEGA88-20MU Atmel, ATMEGA88-20MU Datasheet - Page 140

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ATMEGA88-20MU

Manufacturer Part Number
ATMEGA88-20MU
Description
IC AVR MCU 8K 20MHZ 5V 32-QFN
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA88-20MU

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 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
Package
32MLF EP
Device Core
AVR
Family Name
ATmega
Maximum Speed
20 MHz
Operating Supply Voltage
3.3|5 V
Data Bus Width
8 Bit
Number Of Programmable I/os
23
Interface Type
SPI/TWI/USART
On-chip Adc
8-chx10-bit
Number Of Timers
3
Processor Series
ATMEGA8x
Core
AVR8
Data Ram Size
1 KB
Maximum Clock Frequency
20 MHz
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, ATAVRTS2080A, ATASTK512-EK1-IND
Minimum Operating Temperature
- 40 C
A/d Inputs
8-Channel, 10-Bit
Cpu Speed
20 MIPS
Eeprom Memory
512 Bytes
Input Output
23
Interface
SPI/TWI/USART
Memory Type
Flash
Number Of Bits
8
Package Type
32-pin MLF
Programmable Memory
8K Bytes
Timers
2-8-bit, 1-16-bit
Voltage, Range
4.5-5.5 V
Controller Family/series
AVR MEGA
No. Of I/o's
23
Eeprom Memory Size
512Byte
Ram Memory Size
1KB
No. Of Timers
3
Rohs Compliant
Yes
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
17.2.1
17.2.2
17.3
17.4
140
Timer/Counter Clock Sources
Counter Unit
ATmega48/88/168
Registers
Definitions
The Timer/Counter (TCNT2) and Output Compare Register (OCR2A and OCR2B) are 8-bit reg-
isters. Interrupt request (shorten as Int.Req.) signals are all visible in the Timer Interrupt Flag
Register (TIFR2). All interrupts are individually masked with the Timer Interrupt Mask Register
(TIMSK2). TIFR2 and TIMSK2 are not shown in the figure.
The Timer/Counter can be clocked internally, via the prescaler, or asynchronously clocked from
the TOSC1/2 pins, as detailed later in this section. The asynchronous operation is controlled by
the Asynchronous Status Register (ASSR). The Clock Select logic block controls which clock
source he Timer/Counter uses to increment (or decrement) its value. The Timer/Counter is inac-
tive when no clock source is selected. The output from the Clock Select logic is referred to as the
timer clock (clk
The double buffered Output Compare Register (OCR2A and OCR2B) are compared with the
Timer/Counter value at all times. The result of the compare can be used by the Waveform Gen-
erator to generate a PWM or variable frequency output on the Output Compare pins (OC2A and
OC2B).
set the Compare Flag (OCF2A or OCF2B) which can be used to generate an Output Compare
interrupt request.
Many register and bit references in this document are written in general form. A lower case “n”
replaces the Timer/Counter number, in this case 2. However, when using the register or bit
defines in a program, the precise form must be used, that is, TCNT2 for accessing
Timer/Counter2 counter value and so on.
The definitions in
Table 17-1.
The Timer/Counter can be clocked by an internal synchronous or an external asynchronous
clock source. The clock source clk
bit in the ASSR Register is written to logic one, the clock source is taken from the Timer/Counter
Oscillator connected to TOSC1 and TOSC2. For details on asynchronous operation, see
– Asynchronous Status Register” on page
“Timer/Counter Prescaler” on page
The main part of the 8-bit Timer/Counter is the programmable bi-directional counter unit.
17-2
BOTTOM
MAX
TOP
shows a block diagram of the counter and its surrounding environment.
See “Output Compare Unit” on page 141.
Definitions
T2
The counter reaches the BOTTOM when it becomes zero (0x00).
The counter reaches its MAXimum when it becomes 0xFF (decimal 255).
The counter reaches the TOP when it becomes equal to the highest value in the
count sequence. The TOP value can be assigned to be the fixed value 0xFF
(MAX) or the value stored in the OCR2A Register. The assignment is depen-
dent on the mode of operation.
).
Table 17-1
are also used extensively throughout the section.
T2
151.
is by default equal to the MCU clock, clk
158. For details on clock sources and prescaler, see
for details. The compare match event will also
I/O
. When the AS2
2545S–AVR–07/10
“ASSR
Figure

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