AT90PWM1-16SU Atmel, AT90PWM1-16SU Datasheet - Page 114

• Manufacturer Part Number: AT90PWM1-16SU
• Description: MCU AVR 8K FLASH 16MHZ 24-SOIC
• Manufacturer: Atmel
• Series: AVR® 90PWM Lightingr

Specifications of AT90PWM1-16SU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 19
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 105°C
• Package / Case: 24-SOIC (7.5mm Width)
• Processor Series: AT90PWMx
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 512 B
• Interface Type: SPI
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 19
• Number Of Timers: 2
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATAVRFBKIT, ATAVRISP2
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 11 Channel
• For Use With: ATSTK600-SOIC - STK600 SOCKET/ADAPTER FOR SOIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

114
AT90PWM1
Figure 15-9. Phase and Frequency Correct PWM Mode, Timing Diagram
The Timer/Counter Overflow Flag (TOVn) is set at the same timer clock cycle as the OCRnx
Registers are updated with the double buffer value (at BOTTOM). When either OCRnA or ICRn
is used for defining the TOP value, the OCnA or ICFn Flag set when TCNTn has reached TOP.
The Interrupt Flags can then be used to generate an interrupt each time the counter reaches the
TOP or BOTTOM value.
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 TCNTn and the OCRnx.
As
cal in all periods. Since the OCRnx Registers are updated at BOTTOM, the length of the rising
and the falling slopes will always be equal. This gives symmetrical output pulses and is therefore
frequency correct.
Using the ICRn Register for defining TOP works well when using fixed TOP values. By using
ICRn, the OCRnA Register is free to be used for generating a PWM output on OCnA. However,
if the base PWM frequency is actively changed by changing the TOP value, using the OCRnA as
TOP is clearly a better choice due to its double buffer feature.
In phase and frequency correct PWM mode, the compare units allow generation of PWM wave-
forms on the OCnx pins. Setting the COMnx1:0 bits to two will produce a non-inverted PWM and
an inverted PWM output can be generated by setting the COMnx1:0 to three (See
page
port pin is set as output (DDR_OCnx). The PWM waveform is generated by setting (or clearing)
the OCnx Register at the compare match between OCRnx and TCNTn when the counter incre-
ments, and clearing (or setting) the OCnx Register at compare match between OCRnx and
TCNTn when the counter decrements. The PWM frequency for the output when using phase
and frequency correct PWM can be calculated by the following equation:
The N variable represents the prescaler divider (1, 8, 64, 256, or 1024).
Figure 15-9
TCNTn
OCnx
OCnx
Period
117). The actual OCnx value will only be visible on the port pin if the data direction for the
shows the output generated is, in contrast to the phase correct mode, symmetri-
1
f
OCnxPFCPWM
2
3
=
--------------------------- -
2 N TOP
⋅
f
clk_I/O
⋅
4
OCnA Interrupt Flag Set
or ICFn Interrupt Flag Set
(Interrupt on TOP)
(COMnx1:0 = 2)
(COMnx1:0 = 3)
OCRnx/TOP Updateand
TOVn Interrupt Flag Set
(Interrupt on Bottom)
4378C–AVR–09/08
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