SAM7X128_14 Datasheet, PDF (442/662 Pages) ATMEL Corporation – ARM-based Flash MCU

34.5.2.5 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 availablity refer to Table 34-1 ”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 34.6.9 ”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 34.6.9 ”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 34.6.9 ”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.
34.5.2.6 Reset the endpoint to clear the FIFO (pointers). (See, Section 34.6.9 ”UDP Reset Endpoint Register”.)
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
442