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Altera_Forum
Honored Contributor I
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Can you assign TX and RX pins from the JTAG UART core to GPIO expansion header pins

Hello,  

 

I have instantiated a JTAG UART core in a NIOS II running on a DE1-SoC board. Can I assign the TX and RX pins from the UART to pins on the GPIO expansion header? This is to create a serial console with my host computer over putty.  

 

Thanks
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Altera_Forum
Honored Contributor I
213 Views

No, you can't. The JTAG UART allows you to interface to your system via your USB-Blaster, without the need for dedicated I/O pins. Typically (perhaps exclusively - I'm not sure) you use the 'nios2-console' console to give you access to this UART, which operates over JTAG. 

 

If you want a real UART, presented to pins, you need to use a 'true' UART core. Referring to the 'embedded peripherals ip user guide' (https://www.altera.com/en_us/pdfs/literature/ug/ug_embedded_ip.pdf), look at the 'UART Core' or '16550 UART Core'. These will present Tx/Rx I/O, for connection to a standard serial cable, for use with a console. 

 

Whilst you're in that document, read up on the JTAG UART and it's uses too. 

 

Cheers, 

Alex
Altera_Forum
Honored Contributor I
213 Views

Right, the JTAG UART core has no RX and TX "pins" respectively bit signals but 8-bit RX and TX ports with handshake signals.

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