SAM4s bootloader not responding via usb

Discussion around product based on ARM Cortex M4 core.
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talanfree
Posts: 3
Joined: Thu Nov 03, 2016 10:51 am

SAM4s bootloader not responding via usb

Sun Nov 06, 2016 1:26 pm

Hello,
I am trying to communicate with sam4s on my custom board with simple commands given in section 24.5 in datasheet. Bootloader returns answer when is connected via UART. But when when i open terminal and try the same commands when connected to usb it doesn't return anything. USB is successfully enumerated and recognized as ttyACM0. I am running Ubuntu 15.10. Where am getting wrong?
tsvoipio
Posts: 54
Joined: Wed Aug 19, 2015 9:44 pm

Re: SAM4s bootloader not responding via usb

Sun Nov 06, 2016 10:37 pm

Check your master clock. An UART is much more tolerant toward inexact or varying clock frequency than USB.

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-TV
talanfree
Posts: 3
Joined: Thu Nov 03, 2016 10:51 am

Re: SAM4s bootloader not responding via usb

Mon Nov 07, 2016 9:36 am

I am using external clock on XIN pin 12Mhz oscillator from TXC. I checked with a scope. It looks fine.
When USB is attached i can't communicate via UART. I guess it is switched correctly to USB.
talanfree
Posts: 3
Joined: Thu Nov 03, 2016 10:51 am

Re: SAM4s bootloader not responding via usb

Tue Nov 08, 2016 9:32 pm

I've success with communication through USB. The solution is described in atmel
knowledge base
http://atmel.force.com/support/articles ... -ubuntu-PC

Does somebody know why reinitialize usb driver is needed?

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