Atmel Evaluation Kit for the SAM4E Series of Flash Microcontrollers ATSAM4E-EK ATSAM4E-EK Data Sheet
Product codes
ATSAM4E-EK
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
1156
Figure 42-7.
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 be cleared in the end-
point’s UDP_CSRx.
point’s UDP_CSRx.
2.
The microcontroller writes the first data payload to be sent in the FIFO (Bank 0), writing zero or more byte
values in the endpoint’s UDP_FDRx.
values in the endpoint’s UDP_FDRx.
3.
The microcontroller notifies the USB peripheral it has finished writing in Bank 0 of the FIFO by setting the
TXPKTRDY in the endpoint’s UDP_CSRx.
TXPKTRDY in the endpoint’s UDP_CSRx.
4.
Without waiting for TXPKTRDY to be cleared, the microcontroller writes the second data payload to be sent
in the FIFO (Bank 1), writing zero or more byte values in the endpoint’s UDP_FDRx.
in the FIFO (Bank 1), writing zero or more byte values in the endpoint’s UDP_FDRx.
5.
The microcontroller is notified that the first Bank has been released by the USB device when TXCOMP in the
endpoint’s UDP_CSRx is set. An interrupt is pending while TXCOMP is being set.
endpoint’s UDP_CSRx is set. An interrupt is pending while TXCOMP is being set.
6.
Once the microcontroller has received TXCOMP for the first Bank, it notifies the USB device that it has
prepared the second Bank to be sent, raising TXPKTRDY in the endpoint’s UDP_CSRx.
prepared the second Bank to be sent, raising TXPKTRDY in the endpoint’s UDP_CSRx.
7.
At this step, Bank 0 is available and the microcontroller can prepare a third data payload to be sent
.
USB Device
USB Bus
Read
Write
Read and Write at the Same Time
1st Data Payload
2nd Data Payload
3rd Data Payload
3rd Data Payload
2nd Data Payload
1st Data Payload
Data IN Packet
Data IN Packet
Data IN Packet
Microcontroller
Endpoint 1
Bank 0
Endpoint 1
Bank 1
Endpoint 1
Bank 0
Endpoint 1
Bank 0
Endpoint 1
Bank 0
Endpoint 1
Bank 1