Why USB2.0 TxCSR.bit0 can't clear?

twicave Feng

chip6748. take a look code below:

"while(TxCSR.bit0) { TxCsr |= 1<<3;} //bit3 is flush FIFO bit."

why I can't clear bit0 of TxCsr?

If TxCSR is not cleared,

when next In-token is coming, the peripheral will return a ZERO-Frame to host, which is a wrong response.

can you help me?

0 twicave Feng over 15 years ago

the problem has been solved yet.

step1.De-queue tx send queue.

step2.Tear down tx channel.

step3. Set "flush fifo"bit of TxCSR.

be careful. you shouldn't do flush fifo like this:

USB0Reg.TxCSR |= (1<<3);

if TxCSR.bit0 is set yet, you set it again. the correct code is:

U32 dumb = USB0Reg.TxCSR;

dumb &= ~((1<<0)|(1<<1));

dumb |= 1<<3;

USB0Reg.TxCSR = dumb.

0 dabuan over 15 years ago in reply to twicave Feng

Twicave Feng,

If the problem is solved, can you close this thread by verifying your own answer? Thanks.

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