I have written code on a HCS12 uC (Dragon 12Plus Board) that
meets the write wave form (HAS unused) in the HPI Ref. Guide. I verified this on a MSO2014; by verified I mean my HCNTL bits, HCS, and HSD1 bits are all jiving (it looks right) I am simulating HRDY by sending out a manual burst signal on a function generator.
I am using a DSK6713, no daughter card, I am just using the complimentary cable for the micropitch header on the board (requested a sample from Samtec, 40$ cable for free. . or in my case, 2 for 1)
Two Questions (if you please. . .)
1. It does not appear that the EDMA needs to be configured by me. I am referencing
spra720, page 4. It states the following:
Host port servicing is performed without any user intervention. The HPI has a direct connection
to the EDMA and is not programmable by the user. The requests made to the EDMA are
dependent on the host activity, but consist of transfers between the HPI data register (HPID) and
the rest of the system memory. An EDMA channel invisible to the user is set aside for this task
and is not configurable. The host port is capable of transferring data to or from any location in
the DSPs memory map
Does this mean I don't need to worry about programming this at all. I want to write a simple piece of test code to verify values I am writing. Do I need to enable interrupts in the test code? or does it just magically happen as the above document states.
2. I also read that the EDMA sees the DSPINT as an event from the HPI. Right now I am just writing 0 to HPIC. I am assuming that HSTROBE' going low kicks things off, i.e. generates the event for the HPI; am I interpreting this right.
3. Does anybody have an opinion on whether I should connect the grounds of the development boards? I am not sure which way to go on this; my gut tells me the grounds on each board should be common.
O.K. I appreciate anybody who would like to share with me some HPI wisdom
P.S. Any HPI test code out there to make life a little easier?
Cheers,
Jonesy