ATMEGA48-20PU Atmel, ATMEGA48-20PU Datasheet - Page 117

• Manufacturer Part Number: ATMEGA48-20PU
• Description: IC AVR MCU 4K 20MHZ 5V 28DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA48-20PU

• 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: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 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: ATMEGA48x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 512 B
• Interface Type: 2-Wire/SPI/USART/Serial
• 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
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 6-ch x 10-bit
• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 20MHz
• Total Internal Ram Size: 512Byte
• # 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
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 28
• Package Type: PDIP
• For Use With: ATSTK600-TQFP32 - STK600 SOCKET/ADAPTER 32-TQFPATSTK600 - DEV KIT FOR AVR/AVR32770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2545T–AVR–05/11
pare Flag generates an Output Compare interrupt. The OCF1x Flag is automatically cleared
when the interrupt is executed. Alternatively the OCF1x Flag can be cleared by software by writ-
ing 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 Waveform Generation mode
(WGM13:0) bits and Compare Output mode (COM1x1:0) bits. The TOP and BOTTOM signals
are used by the Waveform Generator for handling the special cases of the extreme values in
some modes of operation
A special feature of Output Compare unit A allows it to define the Timer/Counter TOP value (that
is, counter resolution). In addition to the counter resolution, the TOP value defines the period
time for waveforms generated by the Waveform Generator.
Figure 16-4
bit names indicates the device number (n = 1 for Timer/Counter 1), and the “x” indicates Output
Compare unit (A/B). The elements of the block diagram that are not directly a part of the Output
Compare unit are gray shaded.
Figure 16-4. Output compare unit, block diagram.
The OCR1x Register is double buffered when using any of the twelve Pulse Width Modulation
(PWM) modes. For the Normal and Clear Timer on Compare (CTC) modes of operation, the
double buffering is disabled. The double buffering synchronizes the update of the OCR1x Com-
pare Register to either TOP or BOTTOM of the counting sequence. The synchronization
prevents the occurrence of odd-length, non-symmetrical PWM pulses, thereby making the out-
put glitch-free.
The OCR1x Register access may seem complex, but this is not case. When the double buffering
is enabled, the CPU has access to the OCR1x Buffer Register, and if double buffering is dis-
abled the CPU will access the OCR1x directly. The content of the OCR1x (Buffer or Compare)
Register is only changed by a write operation (the Timer/Counter does not update this register
automatically as the TCNT1 and ICR1 Register). Therefore OCR1x is not read via the high byte
shows a block diagram of the Output Compare unit. The small “n” in the register and
OCRnxH buffer (8-bit)
(See “Modes of operation” on page
OCRnxH (8-bit)
BOTTOM
OCRnx buffer (16-bit register)
TEMP (8-bit)
TOP
OCRnx (16-bit register)
OCRnxL buffer (8-bit)
OCRnxL (8-bit)
DATA BUS
Waveform generator
WGMn3:0
=
(16-bit comparator )
(8-bit)
COMnx1:0
TCNTnH (8-bit)
ATmega48/88/168
119.)
OCFnx (Int.req.)
TCNTn (16-bit counter)
TCNTnL (8-bit)
OCnx
117