ATMEGA16-16MQ Atmel, ATMEGA16-16MQ Datasheet - Page 103

MCU AVR 16K FLASH 16MHZ 44-QFN

ATMEGA16-16MQ

Manufacturer Part Number
ATMEGA16-16MQ
Description
MCU AVR 16K FLASH 16MHZ 44-QFN
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheet

Specifications of ATMEGA16-16MQ

Core Processor
AVR
Core Size
8-Bit
Speed
16MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
Program Memory Size
16KB (8K x 16)
Program Memory Type
FLASH
Eeprom Size
512 x 8
Ram Size
1K x 8
Voltage - Supply (vcc/vdd)
4.5 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
44-VQFN Exposed Pad
Processor Series
ATMEGA16x
Core
AVR8
Data Bus Width
8 bit
Data Ram Size
1 KB
Mounting Style
SMD/SMT
3rd Party Development Tools
EWAVR, EWAVR-BL
Development Tools By Supplier
ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
For Use With
ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK500 - PROGRAMMER AVR STARTER KIT
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
2466T–AVR–07/10
Figure 46. Fast PWM Mode, Timing Diagram
The Timer/Counter Overflow Flag (TOV1) is set each time the counter reaches TOP. In addition
the OC1A or ICF1 Flag is set at the same timer clock cycle as TOV1 is set when either OCR1A
or ICR1 is used for defining the TOP value. If one of the interrupts are enabled, the interrupt han-
dler routine can be used for updating the TOP and compare values.
When changing the TOP value the program must ensure that the new TOP value is higher or
equal to the value of all of the Compare Registers. If the TOP value is lower than any of the
Compare Registers, a compare match will never occur between the TCNT1 and the OCR1x.
Note that when using fixed TOP values the unused bits are masked to zero when any of the
OCR1x Registers are written.
The procedure for updating ICR1 differs from updating OCR1A when used for defining the TOP
value. The ICR1 Register is not double buffered. This means that if ICR1 is changed to a low
value when the counter is running with none or a low prescaler value, there is a risk that the new
ICR1 value written is lower than the current value of TCNT1. The result will then be that the
counter will miss the compare match at the TOP value. The counter will then have to count to the
MAX value (0xFFFF) and wrap around starting at 0x0000 before the compare match can occur.
The OCR1A Register however, is double buffered. This feature allows the OCR1A I/O location
to be written anytime. When the OCR1A I/O location is written the value written will be put into
the OCR1A Buffer Register. The OCR1A Compare Register will then be updated with the value
in the Buffer Register at the next timer clock cycle the TCNT1 matches TOP. The update is done
at the same timer clock cycle as the TCNT1 is cleared and the TOV1 Flag is set.
Using the ICR1 Register for defining TOP works well when using fixed TOP values. By using
ICR1, the OCR1A Register is free to be used for generating a PWM output on OC1A. However,
if the base PWM frequency is actively changed (by changing the TOP value), using the OCR1A
as TOP is clearly a better choice due to its double buffer feature.
In fast PWM mode, the compare units allow generation of PWM waveforms on the OC1x pins.
Setting the COM1x1:0 bits to 2 will produce a non-inverted PWM and an inverted PWM output
can be generated by setting the COM1x1:0 to 3 (See
value will only be visible on the port pin if the data direction for the port pin is set as output
(DDR_OC1x). The PWM waveform is generated by setting (or clearing) the OC1x Register at
the compare match between OCR1x and TCNT1, and clearing (or setting) the OC1x Register at
the timer clock cycle the counter is cleared (changes from TOP to BOTTOM).
TCNTn
OCnx
OCnx
Period
1
2
3
4
5
6
Table 44 on page
7
ATmega16(L)
8
OCRnx / TOP Update and
TOVn Interrupt Flag Set and
OCnA Interrupt Flag Set
OCnA Interrupt Flag Set
(Interrupt on TOP)
110). The actual OC1x
(COMnx1:0 = 2)
(COMnx1:0 = 3)
103

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