Datasheet

1015
SAM4S Series [DATASHEET]
Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14
40.6.2.5 Transmit Data Cancellation
Some endpoints have dual-banks whereas some endpoints have only one bank. The procedure to cancel
transmission data held in these banks is described below.
To see the organization of dual-bank availability refer to Table 40-1 ”USB Endpoint Description”.
Endpoints Without Dual-Banks
There are two possibilities: In one case, TXPKTRDY field in UDP_CSR has already been set. In the other
instance, TXPKTRDY is not set.
 TXPKTRDY is not set:
̶ Reset the endpoint to clear the FIFO (pointers). (See Section 40.7.9 ”UDP Reset Endpoint Register”.)
 TXPKTRDY has already been set:
̶ Clear TXPKTRDY so that no packet is ready to be sent
̶ Reset the endpoint to clear the FIFO (pointers). (See Section 40.7.9 ”UDP Reset Endpoint Register”.)
Endpoints With Dual-Banks
There are two possibilities: In one case, TXPKTRDY field in UDP_CSR has already been set. In the other
instance, TXPKTRDY is not set.
 TXPKTRDY is not set:
̶ Reset the endpoint to clear the FIFO (pointers). (See Section 40.7.9 ”UDP Reset Endpoint Register”.)
 TXPKTRDY has already been set:
̶ Clear TXPKTRDY and read it back until actually read at 0.
̶ Set TXPKTRDY and read it back until actually read at 1.
̶ Clear TXPKTRDY so that no packet is ready to be sent.
̶ Reset the endpoint to clear the FIFO (pointers). (See Section 40.7.9 ”UDP Reset Endpoint Register”.)