We are trying to figure out what the AM335x USB behavior will be in the following scenario.
USB configured as a device.
Host tries to read a bulk pipe, but there is no data in the Tx FIFO.
The SENDSTALL bit is not set.
The USB Functional description in the TRM does not appear to cover this.
Ideally, the USB would return a NAK, and generate an interrupt we could use to trigger a data transfer to the FIFO.
Anyone familiar enough with the USB module to answer this?
NAK token packet will be sent if TxPktRdy (D0) bit and SENDSTALL (D4) is not set and an interrupt will be generated with Underrun (D2) bit set in TXCSR register.
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Thanks for the prompt answer. This solution looks like what we would need to use the internal USB hardware.
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