ATTINY24A-SSUR Atmel, ATTINY24A-SSUR Datasheet - Page 96

• Manufacturer Part Number: ATTINY24A-SSUR
• Description: MCU AVR 2KB FLASH 20MHZ 14SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY24A-SSUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 12
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 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: *
• Package: 14SOIC W
• Device Core: AVR
• Family Name: ATtiny
• Maximum Speed: 20 MHz
• Operating Supply Voltage: 2.5|3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 12
• Interface Type: SPI/USI
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

96
ATtiny24A/44A/84A
applications. High frequency allows physically small sized external components (coils, capaci-
tors), hence reduces total system cost.
The PWM resolution for fast PWM can be fixed to 8-, 9-, or 10-bit, or defined by either ICR1 or
OCR1A. The minimum resolution allowed is 2-bit (ICR1 or OCR1A set to 0x0003), and the max-
imum resolution is 16-bit (ICR1 or OCR1A set to MAX). The PWM resolution in bits can be
calculated by using the following equation:
In fast PWM mode the counter is incremented until the counter value matches either one of the
fixed values 0x00FF, 0x01FF, or 0x03FF (WGM1[3:0] = 5, 6, or 7), the value in ICR1
(WGM1[3:0] = 14), or the value in OCR1A (WGM1[3:0] = 15). The counter is then cleared at the
following timer clock cycle. The timing diagram for the fast PWM mode is shown in
on page
The TCNT1 value is in the timing diagram shown as a histogram for illustrating the single-slope
operation. The diagram includes non-inverted and inverted PWM outputs. The small horizontal
line marks on the TCNT1 slopes represent compare matches between OCR1x and TCNT1. The
OC1x interrupt flag will be set when a compare match occurs.
Figure 12-7.
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
TCNTn
OCnx
OCnx
Period
96. The figure shows fast PWM mode when OCR1A or ICR1 is used to define TOP.
1
Fast PWM Mode, Timing Diagram
2
3
R
FPWM
4
=
5
log
---------------------------------- -
6
(
log
TOP
2 ( )
+
7
1
)
8
OCRnx/TOP Update and
TOVn Interrupt Flag Set and
OCnA Interrupt Flag Set
or ICFn Interrupt Flag Set
(Interrupt on TOP)
(COMnx[1:0] = 2)
(COMnx[1:0] = 3)
8183C–AVR–03/11
Figure 12-7