AT91RM9200-CI-002 Atmel, AT91RM9200-CI-002 Datasheet - Page 561

• Manufacturer Part Number: AT91RM9200-CI-002
• Description: IC ARM9 MCU 256 BGA
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91RM9200-CI-002

• Core Processor: ARM9
• Core Size: 16/32-Bit
• Speed: 180MHz
• Connectivity: EBI/EMI, Ethernet, I²C, MMC, SPI, SSC, UART/USART, USB
• Peripherals: POR
• Number Of I /o: 122
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: ROM
• Ram Size: 48K x 8
• Voltage - Supply (vcc/vdd): 1.65 V ~ 1.95 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 256-BGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

1768I–ATARM–09-Jul-09
Using Endpoints With Ping-pong Attribute
The use of an endpoint with ping-pong attributes is necessary during isochronous transfer. To
be able to guarantee a constant bandwidth, the microcontroller must prepare the next data pay-
load to be sent while the current one is being sent 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.
Figure 34-6. Bank Swapping Data IN Transfer for Ping-pong Endpoints
When using a ping-pong endpoint, the following procedures are required to perform Data IN
transactions:
1. The microcontroller checks if it is possible to write in the FIFO by polling TXPKTRDY to
2. The microcontroller writes the first data payload to be sent in the FIFO (Bank 0), writing
3. The microcontroller notifies the USB peripheral it has finished writing in Bank 0 of the
4. Without waiting for TXPKTRDY to be cleared, the microcontroller writes the second
5. The microcontroller is notified that the first Bank has been released by the USB device
6. Once the microcontroller has received TXCOMP for the first Bank, it notifies the USB
7. At this step, Bank 0 is available and the microcontroller can prepare a third data pay-
be cleared in the endpoint’s UDP_CSRx register.
zero or more byte values in the endpoint’s UDP_FDRx register.
FIFO by setting the TXPKTRDY in the endpoint’s UDP_CSRx register.
data payload to be sent in the FIFO (Bank 1), writing zero or more byte values in the
endpoint’s UDP_FDRx register.
when TXCOMP in the endpoint’s UDP_CSRx register is set. An interrupt is pending
while TXCOMP is being set.
device that it has prepared the second Bank to be sent rising TXPKTRDY in the end-
point’s UDP_CSRx register.
load to be sent
Microcontroller
1 st Data Payload
2 nd Data Payload
3 rd Data Payload
.
Bank 0
Endpoint 1
Bank 1
Endpoint 1
Bank 0
Endpoint 1
Write
USB Device
Bank 0
Endpoint 1
Bank 1
Endpoint 1
Bank 0
Endpoint 1
Read
Read and Write at the Same Time
USB Bus
AT91RM9200
2 nd Data Payload
3 rd Data Payload
1 st Data Payload
Data IN Packet
Data IN Packet
Data IN Packet
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