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NickK

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About NickK

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    Near Guildford, UK
  1. Hi, Just had a look at the code whilst I have a biscuit and drink break. I see you're using SLEEP pin by default: power to the H bridges is cut so if the load requires the current rather than friction to hold that could mean the the focuser moving especially with momentum generated by speed with mass. re-enabling after a sleep, although it doesn't reset the microstep count in the driver, the stepper motor itself may step to the next winding (ie 1/2 or full step) there's a 1ms delay before the DV8825 before the stepper driver is ready to take any instructions such as a STEP operation, there's a 250us delay using operations in call in step() before attempting the step in the 4988 driver. In the end the DRV8825 doesn't get that hot, even when micro stepping so it may be better defaulting to not sleep. It should be an easy exercise to create the 8825 from the 4988 by a subclass and override of a delay method.. (or a little refactoring to make a DRV base class for both drivers).
  2. Started playing with GNU Octave. Given my MacBook pro memory slot has died I'm down to 8GB and slow CPU.. this makes the entire thing more portable and a damn sight more elegant. Guider image:
  3. Using a 3D printer with masking ink.. then let dry (put a heater under the bed).. and etch at leisure. You could then easily switch out for a drilling head.
  4. NickK

    SGL 2018 SP Bookings

    Sorry not this year.. I am considering next year
  5. NickK

    Automation project

    Probably a little late in responding I deliberately kept with the C2 because it's passively cooled, thus no cooling fan vibration on the mount/scope. I don't see why this wouldn't simply move straight over to the XU4 or the N.
  6. NickK

    INDI on the Rocks

    Yes - I rebuilt Kstars/INDI and the tools in 64bit too although it's 2GB on chip, using 64bit expands the number of registers and opens up other optimisations. I used the C2 because it's passively cooled. More info in the original thread:
  7. NickK

    INDI on the Rocks

    I've been using a 64bit ODroid C2 running ubuntu with everything running on it - including astrometry (132GB of SSD based indices)! I don't use a seperate client-server topology - instead simply keep it all on one system then remote desktop into it from which ever system over WiFi.
  8. NickK

    CNC equipment

    I thought you needed some oil cycled to keep the bit and piece cool? Interesting
  9. Ahhh.. this the twist I didn't get to make it accelerate or finalise it - life got in the way. For example - steppers values only sync up at specific steps in the cycle. At 1/32 micro stepping - only at step 17 does the step sync with 1x stepping. So to switch you would need to 1/32 micro step to step 17 before switching the 1/16 etc (which is now step 9)- this also impacts the reset position: // on reset the step position homed depends on microstep mode #define RESET_HOME_STEP_POSITION_1 1 #define RESET_HOME_STEP_POSITION_2 2 #define RESET_HOME_STEP_POSITION_4 3 #define RESET_HOME_STEP_POSITION_8 5 #define RESET_HOME_STEP_POSITION_16 9 #define RESET_HOME_STEP_POSITION_32 17 Now imagine switching between micro stepping like an automatic gearbox on the car depending on the velocity of focuser- with the stepping knowing it has 400K microsteps to do it may be better to sync through to 1x stepping then operate in 32 step leaps at 1x speed before slowing down to 1/32 again for the final sets of steps. Yes - I use micro steps for counting, however the step count is a max of 0x0000-0xFFFF or 65K steps. Which when you have a 1:100 gearbox and 1/32 stepping on a 1.8deg step and 2.8 turns of the focuser .. results in about 1.6 million steps limit to limit An extreme example.. however 65K for a full range isn't good. Lastly I was researching an 'automatic' way of detecting the range of the focuser. It attempts to find each limit switch and then calculate the full range of counts. So that way it will not attempt to move and hit the limit - it already knows there's a limit that will be hit before it accepts the move. I agree the MF protocol isn't great - many of the protocols in the industry aren't designed but evolved..
  10. Interesting the DRV8834 only does 2.5-10.8V max. The reason I went with the specific stepper and DRV8825 (sorry 2285 was my mistake!) was that it handled 12-14V which means you get good back EMF resist and is easily powered from a car battery/PSU that's powering the rest of the hardware (cameras, filter wheels etc). "1.9 us; they can be as short as 1 us when using the A4988." this is something to be weary. "DRV8834 only has two pins for setting its microstep mode" the DRV8825 has three pins M0,1,2 like the 4988. So basically the DRV8834 is a low voltage high current. Whereas the 8825 is a high voltage and medium current. You need some voltage headroom to overcome the EMF so the step is a solid positive step rather than having it fail to step when under physical load. The 3.8V stepper is recommended to have 12V to step but you do need to set the chopper part of the driver to limit the current or the stepper gets really hot The other thing I was looking at is adding an IR remote control for INDI for the apple mac IR remote then you can manually move the focus without touching the scope.
  11. I'd be happy slotting into to the driver for the DRV8825 - a current chopper driver. Only thing I couldn't see at the moment in the code is the stepping sync points when micro stepping. So when you change down to 1 then 1/2 then 1/4 .. 1/32 for example the point on the stepper when the stepping align is specific to the microstepping driver. Thread, development and sources:
  12. Ahh I've already done just this! I have the INDI based moonlite controller (ODroid C2) --USB--> Arduino Uno -> DRV 8825 -> 3.8V 650mA stepper motor with 100:1 gearbox I made the moonlite focuser protocol have a few better commands. Torque on this is stupidly high - hence the need for a couple of stop switches. However it means I can hang a heavy set of cameras off the focuser. The Pentax only has a 1:1 focuser - hence the need to have both high torque and accuracy. The system can also step in 1/32. Quite happy to slot into this - can share the code if you'd like. Note entirely finished (ie it won't shift between stepping speeds) so will detect limit stops. Issue here is how to signify to INDI that the limit stop is achieved. These are some of the shortcomings of the moonlight focuser protocol.
  13. NickK

    OpenCV for the QHY5 on Linux

    You may find that you need additional dependencies - sometimes you can apt get the source packages. Judging by your original post - it sounds like there's a piece of code or a configuration that is needed. Sometimes drivers installed only detect each other at start up so also worth trying a reboot.
  14. Well I'm getting bored .. with the cloudy winters night.. so I think I may pic thus up again I need some maths in my life and sometimes it's good to take a step back and view with fresh eyes. I may be also tempted to look at using AI on the residual noise layer in detecting if a pixel is noise or not. At this pixel value level, this is critical - the focus is not if this pixel is noise or not but how much of the pixel value is noise. So I will start researching the AI noise estimation and see if there's any mileage. Additionally I will start looking at some improvements for performance. I don't think it's worth hitting the GPU yet but there's definitely some algorithmic speed ups that could be done.
  15. NickK

    OpenCV for the QHY5 on Linux

    Surely it's just recompiling the OpenCV .. as long as it has a back end for SIMD instructions. There is an OpenCL variant of OpenCV but the issue there is, again, the GPU code needs to be specific for the architecture to get any real performance boost - especially with the shared memory systems on embedded (such as PI and Odroid etc).
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