talking to grbl directly

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Christian Meyer

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Jan 13, 2020, 8:02:19 AM1/13/20
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I'm trying to talk to GRBL directly. Here's what I'm doing:

* ssh to lasersaur
* service stop driveboardapp.sh
* screen /dev/ttyO1 57600
* reset atmel (pulling Jumper auto_reset)

Unfortunately screen only shows scrambled output.

I guess the serial device is correct, otherwise I wouldn't see anything, right?
Is the baud rate right? I already tried all of the usual rates, but none is working.

Thanks!

Martin Renold

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Jan 13, 2020, 4:17:11 PM1/13/20
to 'Ray Debs' via lasersaur
Are you expecting the right thing? It's a binary protocol. https://github.com/nortd/driveboardapp/blob/master/firmware/src/protocol.c#L21-L26
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Christian Meyer

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Jan 14, 2020, 5:53:28 AM1/14/20
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...that's what I'm expecting ;-) !

Am Montag, 13. Januar 2020 22:17:11 UTC+1 schrieb Martin Renold:
Are you expecting the right thing? It's a binary protocol. https://github.com/nortd/driveboardapp/blob/master/firmware/src/protocol.c#L21-L26

Am Mo, 13. Jan 2020, um 14:02, schrieb 'Christian Meyer' via lasersaur:
I'm trying to talk to GRBL directly. Here's what I'm doing:

* ssh to lasersaur
* service stop driveboardapp.sh
* screen /dev/ttyO1 57600
* reset atmel (pulling Jumper auto_reset)

Unfortunately screen only shows scrambled output.

I guess the serial device is correct, otherwise I wouldn't see anything, right?
Is the baud rate right? I already tried all of the usual rates, but none is working.

Thanks!


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Christian Meyer

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Jan 15, 2020, 10:17:56 AM1/15/20
to lasersaur
Nobody?

jet townsend

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Jan 15, 2020, 12:14:41 PM1/15/20
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Yeah, I would expect binary "garbage" instead of ASCII.

On 1/13/2020 4:15 PM, Martin Renold wrote:
> Are you expecting the right thing? It's a binary protocol.
> https://github.com/nortd/driveboardapp/blob/master/firmware/src/protocol.c#L21-L26
>
> Am Mo, 13. Jan 2020, um 14:02, schrieb 'Christian Meyer' via lasersaur:
>> I'm trying to talk to GRBL directly. Here's what I'm doing:
>>
>> * ssh to lasersaur
>> * service stop driveboardapp.sh
>> * screen /dev/ttyO1 57600
>> * reset atmel (pulling Jumper auto_reset)
>>
>> Unfortunately screen only shows scrambled output.
>>
>> I guess the serial device is correct, otherwise I wouldn't see
>> anything, right?
>> Is the baud rate right? I already tried all of the usual rates, but
>> none is working.
>>
>> Thanks!
>>
>>
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Christian Meyer

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Jan 15, 2020, 12:19:36 PM1/15/20
to lasersaur
...and what about the wiki page I'm referring? Why is it there, if it's not working? Is this for an older version?
 
Am Mittwoch, 15. Januar 2020 18:14:41 UTC+1 schrieb j...@allartburns.org:
Yeah, I would expect binary "garbage" instead of ASCII.

On 1/13/2020 4:15 PM, Martin Renold wrote:
> Are you expecting the right thing? It's a binary protocol.
> https://github.com/nortd/driveboardapp/blob/master/firmware/src/protocol.c#L21-L26
>
> Am Mo, 13. Jan 2020, um 14:02, schrieb 'Christian Meyer' via lasersaur:
>> I'm trying to talk to GRBL directly. Here's what I'm doing:
>>
>> * ssh to lasersaur
>> * service stop driveboardapp.sh
>> * screen /dev/ttyO1 57600
>> * reset atmel (pulling Jumper auto_reset)
>>
>> Unfortunately screen only shows scrambled output.
>>
>> I guess the serial device is correct, otherwise I wouldn't see
>> anything, right?
>> Is the baud rate right? I already tried all of the usual rates, but
>> none is working.
>>
>> Thanks!
>>
>>
>> --
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>> Groups "lasersaur" group.
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jet townsend

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Jan 15, 2020, 12:26:15 PM1/15/20
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The comments make it clear it's mixed ASCII/binary which is going to
show "scrambled" content on many (most?) tty emulators. You might be
able to launch screen in a way that displays non-ASCII characters as hex
instead of binary garbage.

"The protocol is a ascii/binary hybrid. Markers are printable
ascii values while binary data is transmitted in the extended
ascii range [128,255]"
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Derek Seabury

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Jan 15, 2020, 1:23:45 PM1/15/20
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To clarify, at some point the sending of info to the board was changed from just text to be a bit compressed and have error checking.
As serial communications next to the laser supply can have issues some times and the data rate needs to be high for some jobs to go smoothly these changes were needed.
If I wasn't so rusty I could probably figure out the 6 line python program that could solve your problem... But been a long time!


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Christian Meyer

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Jan 15, 2020, 1:32:08 PM1/15/20
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Thanks for the clarification ! I was hoping to be able to debug my problem described there:


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--
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design     <http://www.allartburns.org>
hacking    <http://www.flatline.net>
consulting <http://www.functionalprototype.com>

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Torsten Martinsen

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Jan 16, 2020, 4:02:40 AM1/16/20
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As Martin indicated, the 'gcode' protocol is not used in the
"Driveboard" version of the firmware, but rather the binary protocol -
which is of course a lot more difficult to test by hand.

So the "scrambled output" that you see may well be the correct data.

-Torsten
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