UART1 (/dev/ttyS1) on DE0-nano-SoC does not work


Hi! This is another question from a newbie.

HPS in DE0-nano-SoC has 2 UARTs. First of them (UART0) is used for console (ttyS0) via USB.
I want to use second UART (UART1) for data transfer from Linux (Debian wheezy armhf).
I used Linux 4.3

My first test was to open /dev/ttyS0 via ssh. (stty -F /dev/ttyS0)
Device was successfully opened and keystrokes successfully transmitted to the serial terminal

But I was unable to open /dev/ttyS1 (stty -F /dev/ttyS1) with error

stty: /dev/ttyS1: input/output error

In /proc/tty/driver/serial I have:

serinfo:1.0 driver revision:
0: uart:16550A mmio:0xFFC02000 irq:35 tx:10401 rx:724 RTS|DTR
1: uart:unknown mmio:0xFFC03000 irq:36

Output of Linux starting:

Serial: 8250/16550 driver, 2 ports, IRQ sharing disabled
[0.204597] ffc02000.serial0: ttyS0 at MMIO 0xffc02000 (irq = 35, base_baud = 6250000) is a 16550A

but no information about ttyS1.

Its seems that ttyS1 is not connected to UART1.

Same problem is in system image from official terasic site
But in Linux image from rocketboards /dev/ttyS1 works well!

How can I activate /dev/ttyS1?

Thanks. Sorry for my english


take a look at the device tree and hps.xml(qsys files) in your altera project!

if (cat proc/device-tree/soc/serial1@ffc03000/status = disable) then
change your device tree src file and enable uart1
if (uart1 = disable (in hps.xml > altera project)) then
change the qsys project and enable uart1(under hps/periph) with the right pinning
end if;
end if;


So!! check your fpga project and your device tree!!!


Enable the UART1 from the Qsys tool for your HPS. And then the regular steps of preloader and Device tree generation, should let you use the UART1.


Hi Murillo,

I have done the same and enabled UART1. I am accessing this throught the HPS using a Linux application. I am able to use ‘open’ on ‘/dev/ttyS1’. However, any write to the UART1(Tx and Rx mapped to GPIO_0 pins), does not produce any output at the pins. Do yo have any idea on this?

I have also tried accessing the UART1 directly via terminal using the following command
update : echo 0xFF < /dev/ttyS1

However, there seems to be no change in signal on the GPIO pins mapped to UART: