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nWrtSpcAvlCount and nReadSpaceAvblCount variables #1
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Hi Marco, Thanks for pointing this out, I have however indeed implemented the examples and did only moderate evaluation of the driver. I have no idea on the consequences this has, all I know is that with all implementations of my code on the slave everything works as expected. If you have an answer from SOES or Microchip I would love to hear and fix it as well. Did you ask them publicly (if so can you share a linkt)? Thanks for your help! |
Hi Danny,
I have no doubt about that, as your code is derived directly from the Microchip example: I think that everybody use it as it is, and, as far as I know, nobody complains.
I think that the EtherCAT core is faster than the microprocessor and so there are always data to read or space to write available, without checking it. Anyway, even if this is the case, is should be clearly described and specified in the datasheet, but there is no mention about it.
I asked about this issues in the SOES GitHub repository but so far no answer aside from the developer's amazement. Have a nice day |
Hi,
So far no answer so today I added a clarification:
I am quite disappointed with the Microchip support ... Regards |
Is there any Update from Microchip? |
Yes, but quite strange: So far no more replies, I am quite confused and perhaps they too. Marco |
okay... I see, I have to test the register content by myself.... have a 80 MHz QSPI -> to fast to drop this datasheet information?! VG |
I test it... it's definitely important with a 80 MHz QSPI... If the FIFO is running out the LAN9252 is returning zeros! Would be great to have datasheet information about this. Because a slower running qspi with DMA makes more sense in my application... |
Many thanks for your report. Marco |
Finally I received an answer from Microchip (after more than one year) Each FIFO will update at about 800nSec. So, we don�t need to poll the register every time since the PIC is running at a slower speed and polling will reduce the speed even further. If we add code to poll the available count, it will further decrease the throughput. If a high-performance MCU is used it is recommended to use a 1uSec delay or poll the available counter. Marco |
I measure it with about 720 ns update rate. So should be a true value. |
Hi Danny,
I see that in file driverSWLAN9252.c the variables nWrtSpcAvlCount and nReadSpaceAvblCount are read, decremented but never used.
According to the LAN9252 data sheet they must be used to see how many bytes we can read/write from /to the process ram fifo.
What do you think?
I know that the same issue is present in the SOES and in the Microchip code, and I already arose the problem to them but so far with no result.
Regards
Marco
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