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Gertbot

Wed Feb 25, 2015 3:10 pm

How can i get support on Gertbot Robotics Board

jamesh
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Re: Gertbot

Wed Feb 25, 2015 3:43 pm

Post here with gertbot in the title - Gert should see it.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Please direct all questions to the forum, I do not do support via PM.

creater
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Re: Gertbot

Thu Feb 26, 2015 7:39 am

Hello Gert
I have two pieces. Raspberry Pi Model B + and 2 stk.Gertbot.
have tried to get them to run with your GUI..og saw your example video several times without seeing what I'm doing wrong ..
when I run the GUI it says. Fatal! Could not open UART check UART avallability (use enable_uart) I have downloaded enable_uart exetcutede exe file but it does not help if I run the GUI. as sodu ./gertbot starts Gui. I can press the connect and it searches for board. but no board is found. hope you have a suggestion as to what I can try.

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Gert van Loo
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Re: Gertbot

Sat Feb 28, 2015 9:43 pm

Sorry for the late reply.
I am not yet sure what is not working.
Is the "Could not open UART" problem now solved?
If so the GUI should find a board.

The gertbot uses the Linux UART drivers.
As such you never need to run the program as 'sudo'.

The enable_uart program MUST be used with 'sudo'.
(It will tell you so if you don't)

creater
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Re: Gertbot

Sun Mar 01, 2015 7:56 pm

Thank you for your feedback My problem is that the GUI not start because of the problem with UART ... tried to run Uarte_enable. exe But it does not help .... should I install the driver? Or

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Gert van Loo
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Re: Gertbot

Sun Mar 01, 2015 8:51 pm

There are no system drivers as it uses the serial port drivers which are standard part of every Linux/Unix.
There is C-code and Python code how to call these system drivers but you don't need those
if you use the Gui.

But default the Raspberry-Pi Linux reserves to UART port for itself.
There are several steps to perform to undo that**.
In order to make that easier 'enable_uart' does all the steps for you
but it does have to edit some 'protected' files thus you have to run it with 'sudo'.

You say you have already downloaded an unpacked the 'enable_uart' program.
The next step is to type:

sudo enable_uart cfr

I will perform the following steps:
1/ Check if the uart has already been enabled
if not
2/ edit some systems files to enable the uart
3/ Ask for you if you want to reboot.
(The Pi has to reboot in order for the changes to be effective)
After that the gertbot should be able to use the uart.

If you type only 'enable_uart' the program tells you what the options are.

**If you look for 'raspberry pi enable uart' on the internet you will find several sites telling you
all the steps you have to make, but the enable_uart program does it all should do it all.

creater
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Re: Gertbot

Mon Mar 02, 2015 7:45 am

Hello Gert. many thanks
That was the information I needed

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Smashukikz
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Re: Gertbot

Thu Mar 05, 2015 4:34 pm

Admin could we make a Gerbot forum? Just to keep fragmentation down...

layal
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Re: Gertbot

Thu Mar 26, 2015 8:33 pm

hello
I have connected a RPi2 with a gertbot
I try to enable uart
I find some information about correcting /boot/cmdline.txt.
enable_uart program tries to do it
but /boot/cmdline.txt file seems not to be present on RPI2
So i am not able to use the gertbot with the gui
did i miss something?

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Re: Gertbot

Fri Mar 27, 2015 9:46 am

layal wrote:enable_uart program tries to do it
but /boot/cmdline.txt file seems not to be present on RPI2
So i am not able to use the gertbot with the gui
did i miss something?
Did you use

Code: Select all

sudo enable_uart

layal
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Re: Gertbot

Fri Mar 27, 2015 6:25 pm

here is what i get with enable_uart on my rpi2

Code: Select all

[email protected] ~/Downloads $ sudo ./enable_uart cf
Error checking /boot/cmdline.txt
Looks like /etc/inittab needs fixing
The file /boot/cmdline.txt does not exist
i never modified the file inittab, should I ?
here is the inittab :
http://pastebin.com/yZsAjf39

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Gert van Loo
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Re: Gertbot

Fri Mar 27, 2015 10:51 pm

i never modified the file inittab, should I ?
yes, you should, comment out the respawn on ttyAMA0:
T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100
Change to :
#T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100
That is the UART

I just got a reply from the foundation:
"No change between Pi1 and Pi2 with cmdline.txt. Raspbian ships with a cmdline.txt. "

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DougieLawson
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Re: Gertbot

Fri Mar 27, 2015 11:14 pm

There's an option in sudo raspi-config to do that edit for you.
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layal
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Re: Gertbot

Sat Mar 28, 2015 4:56 pm

hello, many thanks

I only had to use raspi-config.
in advanced options, I changed "serial" to "no"
then reboot and launch ./gertbot.
my test motor works

thanks again

anthillsocial
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Re: Gertbot

Fri Apr 24, 2015 2:40 pm

Hi I'm not sure if this is the right place to post.

I'm trying to get a Rpi V2 working with the gertbot board and a bipolar stepper motor:
http://www.robotshop.com/uk/12v-17a-667 ... ifications

I've got UART working and have the gertbot GUI up and running, though when I connect the stepper the shaft doesn't move, the motor just vibrates. Any hint or tips? In the GUI I've set:
frequency: 200
steps: 10

and have tried all the step grey, pulse options but nothing seems to work. Its probably pretty obvious that I'm very new to stepper motors so I'd really appreciate pointing in the right direction!

Tom

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Gert van Loo
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Re: Gertbot

Fri Apr 24, 2015 10:50 pm

anthillsocial wrote:Hi I'm not sure if this is the right place to post.

I'm trying to get a Rpi V2 working with the gertbot board and a bipolar stepper motor:
http://www.robotshop.com/uk/12v-17a-667 ... ifications

I've got UART working and have the gertbot GUI up and running, though when I connect the stepper the shaft doesn't move, the motor just vibrates. Any hint or tips? In the GUI I've set:
frequency: 200
steps: 10

and have tried all the step grey, pulse options but nothing seems to work. Its probably pretty obvious that I'm very new to stepper motors so I'd really appreciate pointing in the right direction!

Tom
I have seen that behaviour if:
1/ I connected the wires wrongly
2/ One of the wires is not making contact.
3/ The short-circuit protection kicks in.
You often have to use series resistor with that type of motors.
Measure the coil resistance and calculate the current

(And Yes: This is the right place to post)

anthillsocial
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Re: Gertbot

Sun Apr 26, 2015 10:48 am

Thanks for the reply. I managed to get things working, there seemed to be a loose connection with one of the wires, but I also needed to set "Motor 0" to "Step Grey Off" and initially set the frequency to 1000, after which the frequency can be reduced. Otherwise the motor never seems to start. Why might this be?

I'm also not having much luck with the python driver/module. Using the following minimal example doesn't get any response:

Code: Select all

# Stepper motor control
import gertbot as gb
import time
BOARD = 0         # Which board we talk to 
CHAN  = 0           # channel for stepper
gb.open_uart(0)   # Open the uart interface
gb.set_mode(BOARD, CHAN, gb.MODE_STEPG_OFF)
gb.freq_stepper(BOARD, CHAN, 1000)    # Set the frequency 
gb.move_stepper(BOARD, CHAN, 1000)  # Forwards 
time.sleep(1)                                               # Pause for a sec
gb.move_stepper(BOARD, CHAN, -1000)  # Backwards

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Gert van Loo
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Re: Gertbot

Sun Apr 26, 2015 1:20 pm

and initially set the frequency to 1000, after which the frequency can be reduced.
That does not make sense.
1000Hz is very fast for a motor that size.
With a new motor I always start at 10 and then work my way up.

I am working on a new software release.
As soon as I have finished that, I will try your example.
I strongly suggest you start with stepper frequencies of 50-100 Hz.

By the way: on a Pi you can have BOTH the GUI and your code working as long as you use them 'mutually exclusive'.
After running your program, press the 'read status' button on the GUI and see what state it is in.

Update: I copied and pasted your code and ran it:
python3 try.py
For me it works without problems.

anthillsocial
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Re: Gertbot

Tue Apr 28, 2015 2:37 pm

Hi,

I Just checked and it definitely needs 1000hz before it starts moving, nothing happens at all with anything less.

I also managed to get serial command working by writing my own serial coms script and copying the commands directing from your (excellent) GUI:
https://github.com/anthillsocial/suitca ... troller.py

Atos
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Gertbot motor direction

Tue May 12, 2015 6:01 pm

Hi, I have a problem. I would like to controle a brushed dc motor in both directions with the standard gui interface. I connected and installed everything as descriped in the gertbot manuel. Everything looks good, I started the gertbot brushed dc mode and so the pwm signal (for one direction) on the osciloscope occured. So I connected the motor and it started to move in one direction. Then I tried to pressed the other button to change the direction, but the motor doesn't move. I connected the osciloscope and tried the same button, but there was no pwm signal for the other motor direction. The right direction of the pwm from the gertbot worked fine, but the left direction doesn't. An error message occured at the log file called: "board 0: enabled 1 was negated" Maybe I had forgotten something, i don't know. But after reading three times all the manuels I couldn't find a solution for this problem and I have no idea to fix this. Thanks for help.

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Gert van Loo
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Re: Gertbot

Tue May 12, 2015 6:14 pm

"board 0: enabled 1 was negated"
The means your short-circuit protection kicked in!
If you start a motor you have an in-rush current.
If you go from forward straight to backward a motor will have a huge power surge!

Set a ramp-up time and try again.
Also have a look at this video: https://www.youtube.com/watch?v=1565ZdX ... e=youtu.be

Atos
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Re: Gertbot

Wed May 13, 2015 9:51 am

Now I tried this with the ramp mode, with all time possibilities, but nothing have changed.
The same error occured: "Board 0: Enable 1 was negated"
I am using the an MMFN25CC DC motor http://assets.newport.com/webDocuments- ... /12587.PDF
probably the motor is the problem, but otherwise I must see the negativ pwm at the osci by disconnecting the motor.
For extern power supply i am using an Agilant laboratory power supply, could this case the error?
Thank you for your answer!

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Gert van Loo
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Re: Gertbot

Wed May 13, 2015 11:34 am

Ok, this one has me thrown!
To run in one direction you need the same wires as running in the other direction.
As you said it runs one way thus the other way should work as well.

All I can think off (sorry to say so) is that you have connected the motor & power wrong.
e.g. if you have one side to a driver and the other side to a power/ground it will
seem to run but only in one direction.
Then when you switch direction the motor output will be set high but if it is connected to ground
it will immediately short out, no matter how much ramp up time you set.

Atos
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Re: Gertbot

Wed May 13, 2015 2:29 pm

Hey! I found the problem. I connected everything right. The problem was that I measered the pwm during the motor was connected/running. I had the extern power supply and the oscilloscope on the same socket, so I got a short connection over the bulk with the power supply and the oscilloscope and brigded the motor. When I disconnected the osci everything works fine!
Thank you for your support!

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Gert van Loo
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Re: Gertbot

Wed May 13, 2015 3:34 pm

You are welcome.
As you can see the product is rather robust against short circuiting the outputs.
I am sure there is a condition in which you can blow up the controller chip, but I have not managed to do so yet!

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