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I want to ask some problems about ECP(DMA) on PAR0.
i tried both forward and reverse mode.
The Forward mode can work fine, but i found that
the handshaking is not the same as described in
the datasheet, i got the handshaking as follow:
1. HostClk retains high
2. PeriphACK change from LOW to HIGH
3. HostCLK change from high to LOW.
4. HostCLK retains high and
PeriphACK retains LOW.
As the datasheet indicates that the HOSTClk
should change from high to LOW and wait
for the acknowledgement from PeriphACK.
But i got the reverse.
For the Reverse mode,
I can't make it work.
But i get this :
1. PeriphCLK and HostACK retains HIGH
2. PeriphCLK trigger and HostACK trigger
3. Finally retains HIGH again.
i know it is wrong, but i don't know why.
I followed the example in lpslave/, and just
use most of the codes there.
And also in the forward mode, i got the interrupt
about the ecp_descr, but in the reverse mode,
i can't get interrupt of ecp_eop.
Also, i am not so understand what is the difference
about ecp_descr and ecp_eop interrupt? and
in what condition, i should use?
Any examples which i can follow other than lpslave ?