MartijnPieterse

Serial output on linux

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Hi,

 

I am working my way through the IntroToSpartanFPGABook. And i was stuck in Chapter 20 for about half a day.

 

My problem was that i just could not get the "Z" to appear on my serial port. Which was strange, because with a lot of the other bitfiles i found on this site there was serial data when I did a "cat /dev/ttyUSB1" so I know it wasn't a problem with the board, or with linux (x86_64), or anything other than my own VHDL code.

 

Unfortunately i assumed that the serial port would be programmed correctly, but it was not. I had to do a "stty -F /dev/ttyUSB1 raw", because it was still in the "XON/XOFF" protocol apparently.

 

I tried to put as much search terms I used in the past day in this message to hope that someone with the same problem will manage to find it. :)

 

So now a have a screen full of "Z". On to the next objective, somehow encode the state of the switches into the serial data. Lots of fun. :D

 

Edit: This was on a Papilio Pro. But the same would've probably happened on a One.

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"catting" the serial port is not a good idea, because you are not setting any of its parameters.

 

I suggest using a terminal such as minicom. Alternatively, I can get you some "serialcat" that can set up the parameters, if you are interested.

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I'm fine with using stty now to setup the serial port before using cat. Minicom is something i will try out.

 

My problem was that using cat seemed to work on other bitfiles i loaded, but i think i was just lucky with these ones.

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Hi,

 

>> I suggest using a terminal such as minicom.

thanks, will try that one.

Finding a terminal emulator as I'm used to from windoze was harder than expected (PuTTY works but somehow the menus aren't complete).

 

I use "cat" for binary data, but one has to configure the port as discussed above.

 

You could have a look at my ADC example in the retrocade section. It implements a simple state machine for hex dumping and a FIFO. This would let you for example capture events (even without DAC) at high speed and dump them to PC as fast as the USB interface can handle.

 

>> And i was stuck in Chapter 20 for about half a day.

heh... this whole business is not for the impatient. But if it were easy, everybody could do it :)

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