ATUC128L4U Atmel Corporation, ATUC128L4U Datasheet - Page 92

• Manufacturer Part Number: ATUC128L4U
• Manufacturer: Atmel Corporation

Specifications of ATUC128L4U

• Flash (kbytes): 128 Kbytes
• Pin Count: 48
• Max. Operating Frequency: 50 MHz
• Cpu: 32-bit AVR
• # Of Touch Channels: 17
• Hardware Qtouch Acquisition: Yes
• Max I/o Pins: 36
• Ext Interrupts: 36
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 2
• Uart: 4
• Lin: 4
• Ssc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 12
• Adc Speed (ksps): 460
• Analog Comparators: 8
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 16
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.62 to 3.6
• Operating Voltage (vcc): 1.62 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 6
• Output Compare Channels: 18
• Input Capture Channels: 12
• Pwm Channels: 35
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

8.6.2.11
32142A–12/2011
STALL request
• Special considerations for control endpoints
• STALL handshake and retry mechanism
Table 8-4.
For each endpoint, the STALL management is performed using:
To answer requests with a STALL handshake, STALLRQ has to be set by writing a one to the
STALL Request Set (STALLRQS) bit. All following requests will be discarded (RXOUTI, etc. will
not be set) and handshaked with a STALL until the STALLRQ bit is cleared, by receiving a new
SETUP packet (for control endpoints) or by writing a one to the STALL Request Clear (STALL-
RQC) bit.
Each time a STALL handshake is sent, the STALLEDI bit is set by the USBC and the EPnINT
interrupt is set.
The user can use the descriptor to manage STALL requests. The USBC controller reads the
EPn_CTR_STA_BK0/1.STALLRQ_NEXT bit after successful transactions and if it is one the
USBC controller will set UECON.STALLRQ. The STALL_NEXT bit will be cleared upon receiving
a SETUP transaction and the USBC controller will then clear the STALLRQ bit.
If a SETUP packet is received at a control endpoint where a STALL request is active, the
Received SETUP Interrupt (RXSTPI) bit in UESTAn is set, and the STALLRQ and STALLEDI
bits are cleared. It allows the SETUP to be always ACKed as required by the USB standard.
This management simplifies the enumeration process management. If a command is not sup-
ported or contains an error, the user requests a STALL and can return to the main task, waiting
for the next SETUP request.
The retry mechanism has priority over the STALL handshake. A STALL handshake is sent if the
STALLRQ bit is set and if there is no retry required.
• The control and status fields for the endpoint and bank (EPn_CTR_STA_BK0/1):
• The STALL Request (STALLRQ) bit in UECONn is set to initiate a STALL request.
• The STALLed Interrupt (STALLEDI) bit in UESTAn is set when a STALL handshake has been
31:19
sent.
-
– UNDERF: Underflow status for isochronous IN transfer. See
– OVERF: Overflow status for isochronous OUT transfer. See
– CRCERR: CRC error status for isochronous OUT transfer. See
– STALLRQ_NEXT: Stall request for the next transfer. See
page
page
99.
92.
18
UNDERF
99.
99.
EPn_CTR_STA_BK0/1 structure
Status elements
17
OVERF
16
CRCERR
15:1
-
ATUC64/128/256L3/4U
Control elements
”STALL request” on page
”Data flow error” on
”Data flow error” on
”CRC error” on page
0
STALLRQ_NEXT
92