ATMEGA406-1AAU Atmel, ATMEGA406-1AAU Datasheet - Page 99

• Manufacturer Part Number: ATMEGA406-1AAU
• Description: IC AVR MCU 40K 1MHZ 48LQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA406-1AAU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 1MHz
• Connectivity: I²C
• Peripherals: POR, WDT
• Number Of I /o: 18
• Program Memory Size: 40KB (20K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 25 V
• Data Converters: A/D 10x12b
• Oscillator Type: Internal
• Operating Temperature: -30°C ~ 85°C
• Package / Case: 48-LQFP
• Processor Series: ATMEGA48x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 2 KB
• Interface Type: 2-Wire
• Maximum Clock Frequency: 1 MHz
• Number Of Programmable I/os: 18
• Number Of Timers: 2
• 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
• Minimum Operating Temperature: - 30 C
• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 1MHz
• Total Internal Ram Size: 2KB
• # I/os (max): 18
• Number Of Timers - General Purpose: 2
• Operating Supply Voltage (typ): 5/9/12/15/18/24V
• Operating Supply Voltage (max): 25V
• Operating Supply Voltage (min): 4V
• On-chip Adc: 10-chx12-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -30C to 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 48
• Package Type: LQFP
• Controller Family/series: AVR MEGA
• No. Of I/o's: 18
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 2KB
• Cpu Speed: 1MHz
• Rohs Compliant: Yes
• For Use With: 770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAG770-1005 - ISP 4PORT FOR ATMEL AVR MCU JTAG770-1004 - ISP 4PORT FOR ATMEL AVR MCU SPI
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

16.4
16.5
2548E–AVR–07/06
Counter Unit
Output Compare Unit
The main part of the 16-bit Timer/Counter is the programmable 16-bit bi-directional counter unit.
Figure 16-2
Figure 16-2. Counter Unit Block Diagram
Signal description (internal signals):
The 16-bit counter is mapped into two 8-bit I/O memory locations: Counter High (TCNT1H) con-
taining the upper eight bits of the counter, and Counter Low (TCNT1L) containing the lower eight
bits. The TCNT1H Register can only be indirectly accessed by the CPU. When the CPU does an
access to the TCNT1H I/O location, the CPU accesses the high byte temporary register (TEMP).
The temporary register is updated with the TCNT1H value when the TCNT1L is read, and
TCNT1H is updated with the temporary register value when TCNT1L is written. This allows the
CPU to read or write the entire 16-bit counter value within one clock cycle via the 8-bit data bus.
It is important to notice that there are special cases of writing to the TCNT1 Register when the
counter is counting that will give unpredictable results. The special cases are described in the
sections where they are of importance.
Depending on the mode of operation used, the counter is cleared or incremented at each Timer
Clock (clk
bits (CS1[2:0]). When no clock source is selected (CS1[2:0] = 0) the timer is stopped. However,
the TCNT1 value can be accessed by the CPU, independent of whether clk
CPU write overrides (has priority over) all counter clear or count operations.
The 16-bit comparator continuously compares TCNT1 with the Output Compare Register
(OCR1A). If TCNT equals OCR1A the comparator signals a match. A match will set the Output
Compare Flag (OCF1A) at the next timer clock cycle. If enabled (OCIE1A = 1), the output com-
pare flag generates an output compare interrupt. The OCF1A flag is automatically cleared when
the interrupt is executed. Alternatively the OCF1A flag can be cleared by software by writing a
logical one to its I/O bit location.
Count
Clear
clk
T
T
1
1
). The clk
shows a block diagram of the counter and its surroundings.
TCNTnH (8-bit)
TEMP (8-bit)
T
1
TCNTn (16-bit Counter)
is generated from an internal clock source, selected by the Clock Select
DATA BUS (8-bit)
Increment TCNT1 by 1.
Clear TCNT1 (set all bits to zero).
Timer/Counter clock.
TCNTnL (8-bit)
Count
Clear
Control Logic
ATmega406
T
1
is present or not. A
TOVn
(Int.Req.)
clk
Tn
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