various asi174mini issues

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various asi174mini issues

Postby wulfblat » Thu Jan 04, 2018 4:50 pm

I have an asi174mini with which I am experiencing problems. Some trivial, but others serious.

I have the 174mini plugged into a usb3 port, but when I display the contents of the device ASI_CAMERA_INFO returned from ASIGetControlCaps, IsUSB3Camera is true and IsUSB3Host is false (the opposite of reality).

I also find that this camera fails exposures frequently (ASIGetExpStatus returns a status value of ASI_EXP_FAILED). The failure always occurs at the very end of the exposure, and the longer the exposure time (especially multi-second) the more likely the exposure will fail, but always right at the end of the exposure time (even when I call ASIGetExpStatus in a tight loop).

This is on an idle system with no other cameras active, and nothing else on that specific usb bus.

Is there a way to obtain more detailed information about why the returned status is ASI_EXP_FAILED?

If I plug the 174 mini into the usb hub of a 294MC pro then neither camera works well (or sometimes not at all, with ASIGetNumOfConnectedCameras returning 1 or 0). But if I plug them each into their own usb3 port then both work: the 294mc pro works flawlessly, but the 174 mini behaves as I have described above.

I can use other USB devices plugged into the 294mc pro's usb hub with no problems.

This has lead me to believe that there is an issue with the 174 mini's usb handling.

Is this a common problem with the 174mini, or should I return the camera for a replacement?

If it is common, then how are folks dealing with the 174mini's frequent exposure failures or inability to play nicely with other usb devices?

Thanks,

Leonard

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Re: various asi174mini issues

Postby wulfblat » Thu Jan 04, 2018 7:52 pm

I connected both cameras to a different system to see if the camera behavior differed, and it did.

On the alternate system the asi174mini works fine when plugged into its own USB bus and when plugged into the asi294mc's usb hub.

Both the observatory system and the other system are running the same Linux kernel, but the observatory system (where the failures occur) is a dual core Celeron system, while the system where the camera works well is a quad core I5 system.

But I suspect the issue is caused by the USB controller on the observatory system rather than cpu performance, given that the cpu usage on both systems remains quite low during the exposures.

I guess I will be looking for firmware/BIOS updates for the observatory system.

However the values for IsUSB3Camera and IsUSB3Host remain incorrect for the asi174mm: IsUSB3Camera is always true and IsUSB3Host is always false (even when plugged into a usb3 socket).

The asi294mc pro has the correct values for these two booleans.
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Re: various asi174mini issues

Postby chad » Fri Jan 05, 2018 8:58 am

HI,

Sorry for this issue.
About the USB long exp failed, I will wait for your news. And I also will test it.
About the USB type, it is a bug, I will deal with it. In the next SDK, it will changed to a USB2 camera.

Thanks
chad
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Re: various asi174mini issues

Postby wulfblat » Fri Jan 05, 2018 3:22 pm

chad wrote:HI,

About the USB long exp failed, I will wait for your news. And I also will test it.

About the USB type, it is a bug, I will deal with it. In the next SDK, it will changed to a USB2 camera.

Thanks
chad


Hi Chad,

The USB issue only occurs on the slower system and may not be a problem with the camera itself. Unless you already know of some timing issues in the camera's or SDK's USB handling code, I would not spend time working on it.

Thanks for addressing the USB type bug!

Leonard
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Re: various asi174mini issues

Postby wulfblat » Sat Jan 06, 2018 4:20 pm

chad wrote:HI,

About the USB long exp failed, I will wait for your news. And I also will test it.

Thanks
chad


I am still chasing down the USB issue with the asi174mini. Thus far only this camera has issues on my observatory system (all other cameras and usb devices work well), but I cannot tell what is causing the exposure errors.

Is there a way to enable diagnostic output in the SDK?

I am willing to use a debugger, but without code its difficult to know where to set break points, and while disassembling the SDK binary is an option, it is one I'd rather not take.

Thanks,

Leonard
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Re: various asi174mini issues

Postby wulfblat » Sat Jan 06, 2018 6:41 pm

I discovered that libusb supports setting its log level based upon the environment variable LIBUSB_DEBUG.

With LIBUSB_DEBUG set to 4 (the debug value), the asi174mini worked without error on the observatory computer.

This led me to think that the problem was caused by calling ASIGetExpStatus() in too tight a loop, and so I increased the minimum time between calls to 1000 microseconds (1 millisecond), and once again I was able to capture images (of any exposure) without error.

I notice in the example code provided with the ASI SDK that there is a 10 millisecond delay after ASIStartExposure(), and am wondering if there is also a delay required (for at least some cameras) between the calls to ASIGetExpStatus()?

For this camera and system 1 ms works, but I if there is a known minimum delay I would prefer to use that.

Note that my tests are all performed with the cameras plugged into usb3 sockets.

Leonard
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Re: various asi174mini issues

Postby wulfblat » Sun Jan 07, 2018 3:26 pm

I've continued to work on the timing issue, and realized that the error occurs if ASIGetExpStatus() is called too close to when the exposure has completed in the camera. Increasing the time between calls to ASIGetExpStatus() decreases the chance of hitting this window, but it still exists and you can still hit it, and I have done so both on the 174mini and the 294mc pro.

I cannot think of a way to code around this outside of the SDK. Obviously I do not have access to the SDK code and so I do not know if the error is there or in the camera firmware, but if the SDK's implementation of ASIGetExpStatus() can catch this edge condition and return ASI_EXP_WORKING rather than ASI_EXP_FAILED then we'd have a solution.
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Re: various asi174mini issues

Postby chad » Mon Jan 08, 2018 3:05 am

Hi,
Please send a email to me : chad.cao(at)zwoptical.com
thanks
chad
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Re: various asi174mini issues

Postby wulfblat » Tue Jan 09, 2018 6:01 pm

As closure for this topic, using my redesigned version of indi_asi_ccd I no longer see any issues with my two ASI cameras on my observatory system.

Thanks to Chad for helping out and sending instructions for enabling debug output from the ASI SDK.

Great support is a key reason why I chose ASI cameras.
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