ATxmega32A4U Atmel Corporation, ATxmega32A4U Datasheet - Page 176

• Manufacturer Part Number: ATxmega32A4U
• Manufacturer: Atmel Corporation

Specifications of ATxmega32A4U

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 7
• Twi (i2c): 2
• Uart: 5
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 2
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 4
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 5
• Output Compare Channels: 16
• Input Capture Channels: 16
• Pwm Channels: 16
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

14.8.5
8331A–AVR–07/11
Port Override for Waveform Generation
Figure 14-16. Dual-slope pulse width modulation.
Using dual-slope PWM results in a lower maximum operation frequency compared to the single-
slope PWM operation.
The period register (PER) defines the PWM resolution. The minimum resolution is 2 bits
(PER=0x0003), and the maximum resolution is 16 bits (PER=MAX).
The following equation calculate the exact resolution for dual-slope PWM (R
The PWM frequency depends on the period setting (PER) and the peripheral clock frequency
(fclk
N represents the prescaler divider used. The waveform generated will have a maximum fre-
quency of half of the peripheral clock frequency(fclkPER) when CCA is set to zero (0x0000) and
no prescaling is used. This also applies when using the hi-res extension, since this increases the
resolution and not the frequency.
To make the waveform generation available on the port pins, the corresponding port pin direc-
tion must be set as output. The timer/counter will override the port pin values when the CC
channel is enabled (CCENx) and a waveform generation mode is selected.
Figure 14-17 on page 177
channel will override the port pin output value (OUT) on the corresponding port pin. Enabling
inverted I/O on the port pin (INVEN) inverts the corresponding WG output.
R
f
PWM_DS
PWM_DS
CNT
WG Output
PER
), and can be calculated by the following equation:
=
=
BOTTOM
------------------- -
2NPER
log
---------------------------------- -
fclk
MAX
TOP
(
log
PER
PER
2 ( )
+
1
)
shows the port override for a timer/counter. The timer/counter CC
CCx
Period (T)
CCx=BOTTOM
Atmel AVR XMEGA AU
CCx=TOP
PWM_DS
):
"update"
"match"
176