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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

DIY focuser w/o Motor HAT or PiFace?

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Dear Helge,
if I understand correctly, I must load the astroberry-piface driver, right? Can you confirm that it supports the PiFace Digital 2? My RPi3 runs on Ubuntu Mate, but as I read here ( indilib.org/forum/general/699-astroberry...elease.html?start=24 ) it may not work on Ubuntu Mate.
6 years 6 months ago #19015

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Dear Maurizio,

I am using the "astroberry server", see www.indilib.org/forum/general/2183-astroberry-server/16419.html - which is fantastic. I think it is based on Ubuntu Mate.

It already has the PiFace focuser-driver on board. In a previous post, Radek mentioned that he might also onboard the "astroberry focuser" in a future release, so you could alternatively connect the stepper via a driver board to the Raspberry.

If you are interested, this focuser via arduino nano hansastro.github.io/Focuser/

is also a nice way to manage the focuser, with a 12v bipolar stepper, which has a little bit more torque than the 28byj48 stepper (which I started with).

Best, Helge
6 years 6 months ago #19022

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This is correct. It was originally written for the first revision of PiFace board. I think I will need to release another version for PiFace Digital so the second focuser is available.

Radek
Last edit: 6 years 6 months ago by Radek Kaczorek.
6 years 6 months ago #19041

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I've been busy trying to get myself a PiFace Digital 2 but no luck, these little things seem to disappear faster than they are supplied. Should definitely get one asap. In the meantime I have received a Nema17 motor and a4988 driver board. I have tried to connect the board to the RPi3 as per instructions in INDI Astroberry website, but no luck. When I load the indi_rpifocus driver in indiserver, no Astroberry Focuser tab will show up in Ekos. I have installed INDI Astroberry from the .deb file at sourceforge.net/projects/astroberry/ . Any idea why it's not working?

Maurizio
6 years 6 months ago #19076

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Dear Maurizio,

I am sure you double-checked the stepper pins etc already? Whenever testing a new stepper (and nothing happened), it was the pins. Another cause of errror could be the current control VREF, to limit the current. Does all this match your power supply and stepper?

I also wanted to test the rpi_focuser, but struggling to install - see my other post.

Best, Helge
6 years 6 months ago #19079

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I am going to double check all connections with a multimeter then. One thing that is not clear to me is if I should connect the RESET pin with the SLEEP pin, which is in turn connected to GPIO23 on the RPi3. It does not say anything on the Readme file ( github.com/rkaczorek/astroberry-diy/blob/master/README ), but it is usually connected as shown in many other images on Google (see here ).

Regarding Vref, it should be measured between the GDN pin powering the board and the top of the potentiometer, right? The Nema 17 has a nominal current limit of 1.5 A monophase (does it mean "per coil"?). What value should Vref be set to? 3 V?

Do I need to power the motor via Vmot (nominal tension 3.45 V) or is the board powering it via Vdd?

Sorry for all these questions, which you might find stupid or obvious, but this is the first time I deal with stepper motors.

Maurizio
6 years 6 months ago #19101

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I have double checked all connections and they're alright. This is what I get when I load indi_rpifocus in indiserver:
2017-09-05T17:29:58: Driver indi_gphoto_ccd: pid=2008 rfd=3 wfd=6 efd=7
2017-09-05T17:29:58: Driver indi_asi_ccd: pid=2009 rfd=4 wfd=9 efd=10
2017-09-05T17:29:58: Driver indi_lx200autostar: pid=2010 rfd=5 wfd=12 efd=13
2017-09-05T17:29:58: Driver indi_rpifocus: pid=2011 rfd=8 wfd=15 efd=16
2017-09-05T17:29:58: listening to port 7624 on fd 11

What could the problem be? Could it be that my Ekos client (running on my Mac) does not recognize the driver? I am still puzzled by the SLEEP-RESET connection dilemma.
6 years 6 months ago #19107

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I finally got to load the indi_rpifocus driver, I had to recompile the drivers from source. I get the Astroberry Focuser tab in my Ekos client. I still DO NOT manage to get the motor going. Could anyone who has managed to get the a4988 board working tell me which pins of the board should be connected to?

What port should be used? Default is /dev/ttyUSB0 but that looks wrong.

Thanks!
Last edit: 6 years 6 months ago by Maurizio Baldassarre.
6 years 6 months ago #19109

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First of all (as per A4988 datasheet) - RESET turns off all of the FET outputs. All STEP inputs are ignored until the RESET input is set to high. This means that connecting it to SLEEP will set it to high state and will enable outputs.
Now, ENABLE turns on or off all of the FET outputs. When set to a logic high, the outputs are disabled. This means you need to make sure that it is set to low state.
Take a look at this image to connect the A4988 controller to RPi pins.

Make sure that GPIO pins are connected to proper pins at A4988 i.e. GPIO04 - DIR, GPIO17 - STEP, GPIO22 - M0, GPIO27 - M1, GPIO23 - SLEEP (BTW. please note that GPIO number is not the same as pin number e.g. GPIO04 is pin 7 and GPIO17 is pin 11 etc.) - see the pinout below.
Last edit: 6 years 6 months ago by Radek Kaczorek.
6 years 6 months ago #19113

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Thank you very much Radek,

I have wired everything and checked all connections with a multimeter. The motor just won't work. I'm starting to think it must be some sort of software issue, for instance missing libraries.
I attached pictures of the RPi and board, and screenshots of the "Astroberry Focuser" tab under INDI. Please not that the default port is /dev/ttyUSB0. This is weird, why should it be USB?

When I send move commands via Ekos, the voltage on SLEEP rises to 3.3, so I think the RPi does send commands. I checked the voltage of the motor at rest, and the readout is 1.5 volts on each of the 4 pins relative to motor power supply GND. Strange.

Vref does not go beyond 1.2V. Is that enough?

Any explanation?
6 years 6 months ago #19188

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First of all your stepper motor does not look like 28BYJ-48. Could you specify what motor you're using?
Second, does the stepper motor vibrate or gets warm when steps are sent from the driver? Check it out carefully. Based on your pictures I cannot verify if its connected properly. Pictures showing connectors to the stepper and stepper controller and RPi would be helpful.
You can ignore serial port in the driver. It's a leftover and it's not used. I will remove it from the code for transparency.
6 years 6 months ago #19189

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It's not a 28BYJ-48 (unipolar), but a Nema 17 (bipolar). I don't think the a4988 can drive unipolar motors, so I purchased this one for testing. The motor does not vibrate nor gets warm. Looks like no current is flowing at all. Maybe Vref is too low. The voltage on the motor pins on the driver board rises to 4.6 V while I'm sending commands. Starting to think it's a matter of current.
6 years 6 months ago #19190

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