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Knug's avatar
Knug
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4 years ago

How to handle properly pfl_flash_access_granted & pfl_flash_access_request signals ?

Hi @YuanLi_S_Intel How to handle properly pfl_flash_access_granted & pfl_flash_access_request signals if PFL uses both Flash Programming + FPGA Configuration mode Looked at the PFL doc : https...
JohnT_Altera's avatar
JohnT_Altera
Icon for Regular Contributor rankRegular Contributor
4 years ago

Hi,


I would recommend that you connect the nConfig to weak-pull high before we proceed as this will help on avoiding the device from getting reset.


Knug's avatar
Knug
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4 years ago

Hi @JohnT_Intel

I raised this concern about the pull-up resistor to the FPGA_nconfig line.

However, my colleague came back to tell me that there was a hardware mod on the board adding a pull-up resistor to the FPGA_nconfig line.

I would not have been able to spot that that pull-up resistor modification was connected to the FPGA_nconfig line. My board has a DALE 1441 type (questioned to whether this a 1.44Kohm resistor? or 1441 means something else?)

Instructions they listed specified a 10K pull-up resistor and a 10K is the recommended value your link doc (listed within this ticket) suggested

Does it make a difference to the value of the pull-up? The larger the value the weaker it is. Isn't this the case? or should I attempt to change this to a 10k value one?

You suggested connecting the nConfig to a weak-pull high as this will help on avoiding the device from getting reset. The 1.44K resistor is a stronger pull-up. Will this be the reason of the issue seen ? Do I need to change it to a 10K one (ie weaker pull-up) ?

  • Knug's avatar
    Knug
    Icon for Contributor rankContributor
    4 years ago

    Another meeting I had, my colleague confirmed that the DALE 1441 resistor (same one on his board) is a 10K one. When he unsoldered the resistor on one end he measured it as 10K and he said it was written 10K at the bottom of the resistor which I could not see whilst the resistor is soldered on the board. So FPGA_nconfig looks to have a 10K pull up resistor to 3V3

    What is the problem then?? Why the FPGA cannot be configured? What causes the FPGA_nconfig stay low?