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Altera_Forum
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9 years ago

Route HPS UART pins to FPGA pins DE0 nano SoC

Hi I am using a DE0 nano SoC and I need, for my VHDL design, the RX and TX signals from UART (I understand they are available just for de HPS Cortex A9), but in this case I need them to connec...
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Altera_Forum
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8 years ago

Hello sunshine,

I have done the similar process to enable UART1 using the FPGA option in Qsys. I want to access the UART1 using a Linux application running on the HPS. I have routed the Tx and Rx pins to GPIO_0 pins. Preloader and Device tree was generated and the SD card was updated.

When I try to access the UART1 using 'open("/dev/ttyS1", O_RDWR | O_NOCTTY)' , I am able to get the file descriptor successfully. However any write to the UART1, does not produce any change in the GPIO pins. I have also verfied this by accessing directly the UART1 using 'echo 0xFF < /dev/ttyS1' . This produces no change in the pin voltage, verified using an oscilloscope. I am sure that the routing of GPIO pins is correct, since I have verified assigning '0' and '1' to other GPIO_0 pins and measured the voltages, which were correct.

Do you have a hand on this? what could be the way to debug this further?