ATMEGA16U4-AU Atmel, ATMEGA16U4-AU Datasheet - Page 35

• Manufacturer Part Number: ATMEGA16U4-AU
• Description: MCU AVR 16K FLASH USB 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA16U4-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 26
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Processor Series: ATMEGA16x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1.25 KB
• Interface Type: SPI, TWI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 26
• Number Of Timers: 5
• 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: - 40 C
• On-chip Adc: 10 bit, 12 Channel
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.8
6.8.1
7766F–AVR–11/10
USB
CPU Clock
External
Oscillator
RC oscillator
USB
CPU Clock
External
Oscillator
RC oscillator
Clock switch Algorithm
Switch from external clock to RC clock
non-Idle
non-Idle
Figure 6-4.
Figure 6-5.
if (Usb_suspend_detected())
{
}
Ext
Ext
Usb_ack_suspend();
Usb_freeze_clock();
Disable_pll();
Enable_RC_clock();
while (!RC_clock_ready());
Select_RC_clock();
Disable_external_clock();
3m
3m
Idle
Idle
s
s
Example of clock switching with wake-up from USB Host
Example of clock switching with wake-up from Device
w atchdog wake-up
from power-down
w atchdog wake-up
from power-down
(Suspend)
(Suspend)
2 Upstream Resume from device
1 Resume from Host
RC
RC
// if (UDINT.SUSPI == 1)
// UDINT.SUSPI = 0;
// USBCON.FRZCLK = 1;
// PLLCSR.PLLE = 0;
// CLKSEL0.RCE = 1;
// while (CLKSTA.RCON != 1);
// CLKSEL0.CLKS = 0;
// CLKSEL0.EXTE = 0;
ATmega16/32U4
upstream-resume
1
resume
2
non-Idle
non-Idle
Ext
Ext
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