hoglet Posted September 17, 2016 Report Share Posted September 17, 2016 I'm using the 16 bit input wing (LXC16245 based) and, for physical reasons, I would like to plug this into ports DH/DL on the Duo. When I do this, I'm sometimes experiencing a failure for the design to configure, until the wing is physically removed. I've tracked this down to pin Bit 0 of the wing being low. This connects to D53 which is then routed to the Xilinx INIT_B pin. So it seems like D53 cannot safely be used as a user input (both the shields use this as an output so are fine). Is this a known issue? I can work around this by simply not using Bit 0 of the input wing, and tying it high. But I'm concerned of the possibility of conflicts during configuration, as INIT_B is an open drain output, and can this be driven low. I guess I could go one step further and de solder the pin on the wing that connects to the Duo. Anyone got any thoughts on this? Dave Quote Link to comment Share on other sites More sharing options...
Jack Gassett Posted September 19, 2016 Report Share Posted September 19, 2016 Hello Dave, I was trying to squeeze every pin possible into the DUO design to fill the Arduino Mega footprint. INIT_B has a pullup resistor on it so it will be at 1 during bootup and everything can proceed, but unfortunately it does mean that any input that pulls it down to 0 at bootup will hang up the FPGA... Sorry that was not documented, I'm putting it on my task list to update the documentation for this gotcha. Jack. Quote Link to comment Share on other sites More sharing options...
hoglet Posted September 22, 2016 Author Report Share Posted September 22, 2016 Thanks for confirming this Jack. In the end I just de-soldered bit 0 of the wing, and reconnected the signal elsewhere. It's now working fine. Dave Quote Link to comment Share on other sites More sharing options...
Jack Gassett Posted September 23, 2016 Report Share Posted September 23, 2016 Good, glad to hear you have a solution, sorry for the inconvenience. Jack. Quote Link to comment Share on other sites More sharing options...
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