Visible to Intel only — GUID: cwf1481130037108
Ixiasoft
Visible to Intel only — GUID: cwf1481130037108
Ixiasoft
16.4.2.7.1. FIFO Buffer Overflow and Underflow
For transmit:†
- PBL=4†
- TX watermark = 1†
For these programming values, if the FIFO buffer has only one location empty, the DMA attempts to read four words from memory even though there is only one word of storage available. This results in a FIFO Buffer Overflow interrupt.†
For receive:†
- PBL=4†
- RX watermark = 1†
For these programming values, if the FIFO buffer has only one location filled, the DMA attempts to write four words, even though only one word is available. This results in a FIFO Buffer Underflow interrupt.†
The driver must ensure that the number of bytes to be transferred, as indicated in the descriptor, is a multiple of four bytes. For example, if the bytcnt register = 13, the number of bytes indicated in the descriptor must be rounded up to 16 because the length field must always be a multiple of four bytes.†