No /dev/ttyS2 on ODROID-C2 running Ubuntu?

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No /dev/ttyS2 on ODROID-C2 running Ubuntu?

Unread postby Ameridroid » Fri Feb 09, 2018 6:32 am

On the C0, C1 and C1+ using the Chroma servo module, /dev/ttyS2 is the port used to control it. However, on the C2:

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odroid@odroid64:~$ sudo setserial -g /dev/ttyS[0123]
/dev/ttyS0, UART: undefined, Port: 0x0000, IRQ: 225, Flags: low_latency
/dev/ttyS1, UART: undefined, Port: 0x0000, IRQ: 58, Flags: low_latency


No /dev/ttyS2 or /dev/ttyS3 are available.

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odroid@odroid64:~$ uname -a
Linux odroid64 3.14.79-117 #1 SMP PREEMPT Tue Jan 2 23:46:30 BRST 2018 aarch64 aarch64 aarch64 GNU/Linux

Any ideas?
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Re: No /dev/ttyS2 on ODROID-C2 running Ubuntu?

Unread postby tradetree » Fri Feb 09, 2018 7:33 am

I am the person who reported this initially to Ameridroid. I got an engineer to debug the issue and we discovered that it all works on /dev/ttyS1. I was able to drive my servo on this port. I used the command, "echo 'st' | sudo tee /dev/ttyS1"

So just use ttyS1 instead, but I do now have power issues so that is the next task. I can connect one or two servos only or the power dies.
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Re: No /dev/ttyS2 on ODROID-C2 running Ubuntu?

Unread postby odroid » Fri Feb 09, 2018 12:17 pm

You had to navigate our WiKi first.
https://wiki.odroid.com/odroid-c2/appli ... /gpio/uart

What is the power consumption of the servo motors?
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Re: No /dev/ttyS2 on ODROID-C2 running Ubuntu?

Unread postby Ameridroid » Sat Feb 10, 2018 8:06 am

Have you tried adding additional power to the servo board directly as per the instructions at http://respectech.com/odroid/docs/C1_se ... ual_v3.pdf on pages 5 and 6?
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Re: No /dev/ttyS2 on ODROID-C2 running Ubuntu?

Unread postby Ameridroid » Sat Feb 10, 2018 8:12 am

You can also power the C2 completely and servo board using a higher amperage 5V power supply. But I'd recommend against using the C2's barrel connector or microUSB connector for higher amperage loads as they have pretty lightweight connectors. Connecting to pins 2 and 6 of the header would be the best option. We have an example video at https://youtu.be/9aCuIUUGFFU (not specifically for the servo board, but the concept is the same).
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