AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 511

• Manufacturer Part Number: AT91SAM7S256D-AU
• Description: ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
• Manufacturer: Atmel
• Series: SAM7S256r

Specifications of AT91SAM7S256D-AU

• Rohs: yes
• Core: ARM
• Processor Series: AT91SAM
• Data Bus Width: 16 bit/32 bit
• Maximum Clock Frequency: 55 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 64 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 3 V to 3.6 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: LQFP-64
• Mounting Style: SMD/SMT
• Interface Type: 2-Wire, I2S, SPI, USART
• Length: 7 mm

Figure 35-9. Data OUT Transfer for Non Ping-pong Endpoints
35.5.2.7
RX_DATA_BK0
(UDP_CSRx)
FIFO (DPR)
Content
USB Bus
Packets
An interrupt is pending while the flag RX_DATA_BK0 is set. Memory transfer between the USB device, the FIFO
and microcontroller memory can not be done after RX_DATA_BK0 has been cleared. Otherwise, the USB device
would accept the next Data OUT transfer and overwrite the current Data OUT packet in the FIFO.
During isochronous transfer, using an endpoint with ping-pong attributes is obligatory. To be able to guarantee a
constant bandwidth, the microcontroller must read the previous data payload sent by the host, while the current
data payload is received by the USB device. Thus two banks of memory are used. While one is available for the
microcontroller, the other one is locked by the USB device.
3. The microcontroller is notified that the USB device has received a data payload polling RX_DATA_BK0 in
4. The number of bytes available in the FIFO is made available by reading RXBYTECNT in the endpoint’s
5. The microcontroller carries out data received from the endpoint’s memory to its memory. Data received is
6. The microcontroller notifies the USB device that it has finished the transfer by clearing RX_DATA_BK0 in
7. A new Data OUT packet can be accepted by the USB device.
Using Endpoints With Ping-pong Attributes
the endpoint’s UDP_ CSRx register. An interrupt is pending for this endpoint while RX_DATA_BK0 is set.
UDP_ CSRx register.
available by reading the endpoint’s UDP_ FDRx register.
the endpoint’s UDP_ CSRx register.
Data OUT
PID
Host Sends Data Payload
Written by USB Device
Data OUT 1
Data OUT 1
Set by USB Device
ACK
Host Sends the Next Data Payload
Microcontroller Read
PID
Microcontroller Transfers Data
Data OUT 1
Data OUT2
Interrupt Pending
PID
Data OUT2
NAK
PID
Cleared by Firmware,
Data Payload Written in FIFO
Data OUT
PID
Host Resends the Next Data Payload
Written by USB Device
SAM7S Series [DATASHEET]
Data OUT 2
Data OUT2
6175M–ATARM–26-Oct-12
ACK
PID
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