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Altera_Forum
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12 years ago

How to let FPGA get access to HPS pins

I've got an Arrow SOCkit and it has a USB-UART connected to the HPS' pins, but I'd like to access the UART from the FPGA logic. Is this possible? If so how is it done? Thank you!
Altera_Forum's avatar
Altera_Forum
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8 years ago

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Thanks Marcopoliptica.

After hours of trying all these different multiplexing options I have got it working ;)

I used to Pin Assignments window to identify the correct GPIO routing for the UART/USB external connector (PIN_B25 and PIN_C25). Both of these are NOT on the loan 61 and 62 but in fact 49 and 50! ... so I used the same LOANIO method and exported 49 and 50 which worked and the fitter assigned them to the desired pins.

61 and 62 would always (correctly) get fitted to PIN_B22 and PIN_G22 respectively, but of course the external connector is physically routed to the above pins.

Thanks again for your help,

I can now use the external UART/USB with my softcore processor ;)

RE the voltage error, yes I later realised I just change them from '2.5 V (default)' to '3.3-V LVTTL' and it compiles.

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Hi, I know this thread was started long ago. I have same issue as discussed here and need your help with this. I am playing around with the de1 soc board, so I implemented a UART module and need to test it on the board. However, even after following your solution of loaning 49 and 50, I am unable to get it to work. I have LOAN_IO_OE[49] assigned to 1'b0 and LOAN_IO_OE[50] assigned to 1'b1. LOAN_IO_IN[49] and LOAN_IO_OUT[50] connected to RX and TX of the FPGA logic respectively. The TX light (of the UART) on the board does not blink when I execute the logic to transfer via UART. Not sure where the problem could be from. I hope you can help me with this.