ATMEGA1284P-PU Atmel, ATMEGA1284P-PU Datasheet - Page 158

• Manufacturer Part Number: ATMEGA1284P-PU
• Description: MCU AVR 128K ISP FLASH 40-PDIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA1284P-PU

• 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: 32
• Program Memory Size: 128KB (64K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Processor Series: ATMEGA128x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 16 KB
• Interface Type: 2-Wire/SPI/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 32
• 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, ATAVRRAVEN, ATAVRRZUSBSTICK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• Controller Family/series: AVR MEGA
• No. Of I/o's: 32
• Eeprom Memory Size: 4KB
• Ram Memory Size: 16KB
• Cpu Speed: 20MHz
• Rohs Compliant: Yes
• For Use With: ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600 - DEV KIT FOR AVR/AVR32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

15.11.4
15.11.5
15.11.6
8059D–AVR–11/09
OCR2A – Output Compare Register A
OCR2B – Output Compare Register B
ASSR – Asynchronous Status Register
Match on the following timer clock. Modifying the counter (TCNT2) while the counter is running,
introduces a risk of missing a Compare Match between TCNT2 and the OCR2x Registers.
The Output Compare Register A contains an 8-bit value that is continuously compared with the
counter value (TCNT2). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC2A pin.
The Output Compare Register B contains an 8-bit value that is continuously compared with the
counter value (TCNT2). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC2B pin.
• Bit 6 – EXCLK: Enable External Clock Input
When EXCLK is written to one, and asynchronous clock is selected, the external clock input buf-
fer is enabled and an external clock can be input on Timer Oscillator 1 (TOSC1) pin instead of a
32 kHz crystal. Writing to EXCLK should be done before asynchronous operation is selected.
Note that the crystal Oscillator will only run when this bit is zero.
• Bit 5 – AS2: Asynchronous Timer/Counter2
When AS2 is written to zero, Timer/Counter2 is clocked from the I/O clock, clk
written to one, Timer/Counter2 is clocked from a crystal Oscillator connected to the Timer Oscil-
lator 1 (TOSC1) pin. When the value of AS2 is changed, the contents of TCNT2, OCR2A,
OCR2B, TCCR2A and TCCR2B might be corrupted.
• Bit 4 – TCN2UB: Timer/Counter2 Update Busy
When Timer/Counter2 operates asynchronously and TCNT2 is written, this bit becomes set.
When TCNT2 has been updated from the temporary storage register, this bit is cleared by hard-
ware. A logical zero in this bit indicates that TCNT2 is ready to be updated with a new value.
• Bit 3 – OCR2AUB: Output Compare Register2 Update Busy
When Timer/Counter2 operates asynchronously and OCR2A is written, this bit becomes set.
When OCR2A has been updated from the temporary storage register, this bit is cleared by hard-
ware. A logical zero in this bit indicates that OCR2A is ready to be updated with a new value.
Bit
(0xB3)
Read/Write
Initial Value
Bit
(0xB4)
Read/Write
Initial Value
Bit
(0xB6)
Read/Write
Initial Value
R
7
–
0
R/W
R/W
7
0
7
0
EXCLK
R/W
6
0
R/W
R/W
6
0
6
0
R/W
AS2
5
0
R/W
R/W
TCN2UB
5
0
5
0
R
4
0
R/W
R/W
4
0
4
0
OCR2AUB
OCR2A[7:0]
OCR2B[7:0]
R
3
0
R/W
R/W
3
0
3
0
OCR2BUB
R
2
0
R/W
R/W
2
0
2
0
TCR2AUB
ATmega1284P
R/W
R/W
R
1
0
1
0
1
0
TCR2BUB
I/O
R/W
R/W
0
0
0
0
. When AS2 is
R
0
0
OCR2A
OCR2B
ASSR
158