Serial cable is known under ttyACM0/1

Hi

When I connect ZED Board to the computer,
its serial link will be recognized as
/dev/ttyACM0 or /dev/ttyACM1 device.

However for ZC702, it is knows as /dev/ttyUSB0

I want to know the source of this difference?

Why for the ZED Board we don't simply have /dev/ttyUSB0 again?

Because /dev/ttyACM0 has a lot of problems. For example, when I turn of the board I should exit Minicom.
And then next time that I turn on the board it appears as ttyACM1 not 0 and i should reconfigure every thing again

do you know any solution to this?
thanks

0 Former Member over 13 years ago

mamsadegh,

The Zedboard uses the CY7C64225-28PVXC USB-UART bridge, while the ZC702 board uses the CP2103GM_MLP-28 USB-UART bridge.

The difference in manufactures more than likely explains the difference in enumeration sequencing, and thus the difference in naming schema.

I'll see if there is anyone at Cypress who can better answer your question.
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0 Former Member over 13 years ago

mamsadegh,

My appologies it took so long to get back to you - as I wanted to confirm with the factory the modes of operation you were seeing.

The thing that the factory found, and I confirmed, is that minicom is holding onto the handle and keeping the /dev/ttyACM0 'file' open. Thus, when the kernel tries to enumerate the Cypress USB-UART bridge after a power cycle, it can not open the /dev/ttyACM0 file and errors out. It would appear that the driver then falls over to see if it can open the next available 'file', called /dev/ttyACM1 - which works.

The solution is to write out your minicom configuration to a script, and launch it that way. Then close out, power cycle the board, and finally relaunch minicom.

Let me know if you are successful.
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0 Former Member over 13 years ago

BTW I recently switched from minicom to picocom, which is much handier for this kind of application. No config saving necessary as you give all the required parameters on the commandline (e.g. picocom -b 115200 /dev/ttyUSB0)
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0 Former Member over 13 years ago

hi
thanks for help
the picocom solution is fine
i will continue with that.
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0 Former Member over 13 years ago in reply to Former Member

Great! Glad you were able to get everything working. If you're working on a project, be sure to post it for the community in the Projects Section!

Happy Zynq'ing!
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