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

Bi-monthly release with minor bug fixes and improvements

QHY 5L II CCD + Raspberry Pi 2

  • Posts: 10
  • Thank you received: 2
I've read lots of people talking about the QHY 5L II Guide Camera occasionally giving 'Timeout During Exposure', and have noticed the same myself. Looking into it, I've come across some useful information that I thought I'd share (who knows, it may help someone!).

Firstly, to look at the Raspberry PI 2, USB ports and their capability. Each of the 4 x USB ports are USB 2, and have a maximum data transfer rate of 480Mbps. The USB Speed and Data rates are manageable via the INDI Control panel, and the Data Rate is set at a default of 30 / 255.

The Raspberry Pi (using the default power supply) takes an Input voltage of +5V with 2.5A. However, each USB ports output power is rate limited using a polyfuse, meaning the output power of each USB port is 4.5V with 1.1Ma (See Here: Raspberry Pi2 USB Power )

Taking this a step further, and looking at the QHY 5L II FAQ's, I came across the following interesting comment from the manufacture:
How to avoid Camera Hangs

3.2 If the USB port's voltage not enough? Some computer's USB port +5V is not enough. It may cause the camera always hangs. In this condition you can use a powered USB3.0 HUB to connect camera and get the good +5V power for camera.
QHY 5L II Camera FAQ's

Putting the two together, it appears to me that connecting the QHY Camera directly to a USB port on the RPi2 means that the camera is slightly under power (-0.5V) and according the the manufacturer this can lead to the camera freezing or dropping frames. The recommendation to solve this is to ensure that the camera is connected to a USB port (such as a powered USB 3.0 Hub) that is capable of providing at least +5V power.

Again, this can be taken step further and where the QHY camera is connected directly to the RPi2 USB port along with other devices (Capture Camera, Focusser, Filter Wheel or Mount (EQMod etc) the additional power drawn by other devices may negatively impact the power being supplied the QHY camera. Thus exacerbating the problem even further!
The following user(s) said Thank You: Tom Bardenwerper
5 years 5 days ago #36864

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  • Posts: 102
  • Thank you received: 31
I use this QHY camera. This is very helpful info, thank you for sharing it!
5 years 5 days ago #36874

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