- •Features
- •Disclaimer
- •Overview
- •Block Diagram
- •Pin Descriptions
- •Port B (PB7..PB0)
- •Port C (PC7..PC0)
- •Port D (PD7..PD0)
- •D-/SDATA
- •UGND
- •UVCC
- •UCAP
- •RESET/PC1/dW
- •XTAL1
- •XTAL2/PC0
- •AVR CPU Core
- •Introduction
- •Status Register
- •Stack Pointer
- •TABLE 1.
- •TABLE 2.
- •AVR AT90USB82/162 Memories
- •I/O Memory
- •Clock Systems and their Distribution
- •Clock Switch
- •Exemple of use
- •Swith from external clock to RC clock
- •Switch from RC clock to external clock
- •Clock Sources
- •Default Clock Source
- •External Clock
- •Internal PLL for USB interface
- •Idle Mode
- •Power-down Mode
- •Power-save Mode
- •Standby Mode
- •Analog Comparator
- •Brown-out Detector
- •Watchdog Timer
- •Port Pins
- •Resetting the AVR
- •Reset Sources
- •Power-on Reset
- •External Reset
- •Watchdog Reset
- •USB Reset
- •Watchdog Timer
- •TABLE 2.
- •TABLE 2.
- •Interrupts
- •TABLE 2.
- •Introduction
- •Configuring the Pin
- •Toggling the Pin
- •Reading the Pin Value
- •TABLE 3.
- •Unconnected Pins
- •Alternate Port Functions
- •Register Description for I/O-Ports
- •Timer/Counter0 and Timer/Counter1 Prescalers
- •Internal Clock Source
- •Prescaler Reset
- •External Clock Source
- •8-bit Timer/Counter0 with PWM
- •Overview
- •Registers
- •Definitions
- •Counter Unit
- •Normal Mode
- •Fast PWM Mode
- •8-bit Timer/Counter Register Description
- •Overview
- •Registers
- •Definitions
- •Counter Unit
- •Input Capture Unit
- •Noise Canceler
- •Force Output Compare
- •Normal Mode
- •Fast PWM Mode
- •16-bit Timer/Counter Register Description
- •TABLE 2.
- •TABLE 2.
- •Slave Mode
- •Master Mode
- •Data Modes
- •USART
- •Overview
- •Clock Generation
- •External Clock
- •Frame Formats
- •Parity Bit Calculation
- •TABLE 2.
- •TABLE 3.
- •TABLE 4.
- •Parity Generator
- •TABLE 3.
- •TABLE 2.
- •Receiver Error Flags
- •Parity Checker
- •Disabling the Receiver
- •TABLE 2.
- •Using MPCMn
- •Receiver Flow Control
- •Overview
- •Clock Generation
- •Frame Formats
- •TABLE 2.
- •Data Transfer
- •TABLE 3.
- •USB controller
- •Features
- •Block Diagram
- •Typical Application Implementation
- •Device mode
- •Bus Powered device
- •Introduction
- •Interrupts
- •Power modes
- •Idle mode
- •Power down
- •Freeze clock
- •Memory access capability
- •Memory management
- •PAD suspend
- •D+/D- Read/write
- •Registers description
- •USB general registers
- •USB Software Operating modes
- •USB Device Operating modes
- •Introduction
- •Power-on and reset
- •Endpoint reset
- •USB reset
- •Endpoint selection
- •Endpoint activation
- •Address Setup
- •Detach
- •Remote Wake-up
- •STALL request
- •Special consideration for Control Endpoints
- •STALL handshake and Retry mechanism
- •CONTROL endpoint management
- •Control Write
- •Control Read
- •Overview
- •“Manual” mode
- •Detailed description
- •IN endpoint management
- •“Manual” mode
- •Detailed description
- •Abort
- •Isochronous mode
- •Underflow
- •CRC Error
- •Overflow
- •Interrupts
- •Registers
- •USB device general registers
- •USB device endpoint registers
- •Characteristics
- •Analog Comparator
- •Application Section
- •Boot Reset Fuse
- •Simple Assembly Code Example for a Boot Loader
- •debugWIRE On-chip Debug System
- •Features
- •Overview
- •Physical Interface
- •Software Break Points
- •Limitations of debugWIRE
- •debugWIRE Related Register in I/O Memory
- •Fuse Bits
- •Latching of Fuses
- •Signature Bytes
- •Calibration Byte
- •Signal Names
- •Chip Erase
- •Reading the Flash
- •Reading the EEPROM
- •Electrical Characteristics
- •Absolute Maximum Ratings*
- •DC Characteristics
- •External Clock Drive Waveforms
- •External Clock Drive
- •Maximum speed vs. VCC
- •Supply Current of IO modules
- •Example 1
- •Example 2
- •Example 3
- •Instruction Set Summary
- •Packaging Information
- •TQFP32
RXOUTI shall always be cleared before clearing FIFOCON.
The RWAL bit always reflects the state of the current bank. This bit is set if the firmware can read data from the bank, and cleared by hardware when the bank is empty.
Example with 1 OUT data bank |
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OUT |
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DATA |
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ACK |
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NAK |
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OUT |
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DATA |
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ACK |
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(to bank 0) |
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(to bank 0) |
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RXOUTI |
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SW |
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read data from CPU |
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FIFOCON |
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SW |
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read data from CPU |
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BANK 0 |
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BANK 0 |
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Example with 2 OUT data banks |
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OUT |
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DATA |
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ACK |
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OUT |
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DATA |
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ACK |
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(to bank 0) |
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(to bank 1) |
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RXOUTI |
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SW |
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SW |
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read data from CPU |
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FIFOCON |
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SW |
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read data from CPU |
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BANK 0 |
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BANK 1 |
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Detailed description
IN endpoint management
The data are read by the CPU, following the next flow:
•When the bank is filled by the host, an endpoint interrupt (EPINTx) is triggered, if enabled (RXOUTE set) and RXOUTI is set. The CPU can also poll RXOUTI or FIFOCON, depending on the software architecture,
•The CPU acknowledges the interrupt by clearing RXOUTI,
•The CPU can read the number of byte (N) in the current bank (N=BYCT),
•The CPU can read the data from the current bank (“N” read of UEDATX),
•The CPU can free the bank by clearing FIFOCON when all the data is read, that is:
•after “N” read of UEDATX,
•as soon as RWAL is cleared by hardware.
If the endpoint uses 2 banks, the second one can be filled by the HOST while the current one is being read by the CPU. Then, when the CPU clear FIFOCON, the next bank may be already ready and RXOUTI is set immediately.
IN packets are sent by the USB device controller, upon an IN request from the host. All the data can be written by the CPU, which acknowledge or not the bank when it is full.Overview
198
7707A–AVR–01/07