Cirrus Logic AN83 - Manual (Page 5)

AN83
AN83REV3 5
SOFTWARE CHECKLIST
- When servicing the interrupt always read the
Interrupt Status Queue (ISQ) first. Process that
individual event before reading the ISQ again.
- Having read an ISQ event indicating a valid
recieve frame, never read the ISQ again before
either 1) reading in the entire current receive
frame or 2) issuing an explicit skip command.
Either of these actions will correctly clear that
frame from the CS8900A’s internal memory.
- Always continue reading and processing ISQ
events until reading a 0x0000 from the ISQ.
- After a software or hardware reset, always wait
until the SelfStatus register, bit 7 (INITD) is set
before reading or writing any other registers.
- Allow only one transmit in progress at any given
time. Since the chip dynamically allocates
memory between transmit and recieve frames, it
is possible to fill the internal buffers with transmit
frames. This would prevent reception.
- Don’t reinvent the wheel. Port one of the sample
drivers, if there isn’t a driver for your operating
system. You can find sample drivers at
http://www.cirrus.com/drivers/ethernet/.