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usb remote help

  • 25 Replies
Re: usb remote help
« Reply #20 on: 19 / May / 2009, 16:53:53 »
Hi,  your timings (just running take_picture) work well with SDM firmware & USB is displayed on the screen. Adding a lengthy pause at the end of take_picture makes no difference & all is well.  Now,  if I add this to  my script,  there seems to be some interference from the servo's.

USB is no longer displayed on LCD & shutter trigger don't seem in sync with the code (although pictures are now being taken). So I'm moving the camera with a servo,  then pause,  then take_picture.  What happens,  in fact,  is the shutter fires straight after the servo has rotated

So,  two steps forward.  Camera is firing true,  but servo movement is affecting shutter trigger pulse

G9, Ixus75

Re: usb remote help
« Reply #21 on: 19 / May / 2009, 18:03:30 »
The problems are all in your hardware and Picaxe software.

Can you post the complete Picaxe code ?

Describe the hardware connections in greater detail.


Re: usb remote help
« Reply #22 on: 22 / May / 2009, 03:43:37 »
Hi, I've inverted a KAP rig to move a camera in both x and y axes for an automatic panorama sequence shoot.  There are two servo's in ciruit controlled by the picaxe servo board.  As mentioned,  I've used two wires of the this picaxe servo channel to fire the camera shutter facilitated by CHDK.

Picaxe code is below:

'*** Program constants
' Delay to slow down servo motion (30ms default)
symbol servo_delay = 60
symbol top = 120
symbol bottom =120
symbol left = 80
symbol right = 200
symbol vstep = 20
symbol hstep = 20
symbol pic_delay = 100
symbol camera_steady_delay = 5000

'*** Move forward
for b2 = top to bottom step vstep
 servo 2,b2
 pause servo_delay   
 for b1 = left to right step hstep
  servo 1,b1
  pause camera_steady_delay
  GOSUB take_picture
  pause pic_delay
 next b1
next b2


high 4
pause 30
low 4
pause 30

servo 2,top


G9, Ixus75

Re: usb remote help
« Reply #23 on: 22 / May / 2009, 05:46:26 »
What happens if you run the script with one (each in turn) or both servos disconnected ?

Is the USB cable to the camera fitted with the usual ferrite noise suppressor (the black cylinder clamped over the cable) ?

Maybe that makes a difference ?
« Last Edit: 22 / May / 2009, 06:34:50 by Microfunguy »



Re: usb remote help
« Reply #24 on: 22 / May / 2009, 11:19:07 »
I have encountered a similar problem with motor control equipment. The motor brushes generate RF and upsets the CPU internal oscillator.

If the problem is RF noise.

Isolate you picaxe electronics and power supply from your servo electronics and power supply. Install opto isolators between you picaxe output and your servo motor driver. Install 0.1uf ceramic capacitors directly across your picaxe supply rail on your picaxe chip. Make certain the leads are as short as possible. Do the same directly across the power supply of your servo motor. Isolate both power supply rails directly back to your power supply. On your picaxe supply also use a ferrite noise suppressor.

Re: usb remote help
« Reply #25 on: 24 / May / 2009, 13:05:24 »
Hi,  adding a ferrite thing  makes no difference to the shutter timing. Disconnecting the servo's does change the shutter release timing.  When I get a chance I'll solder some decoupling caps,  & add a ferrite to the picaxe supply.Certainly if the servo's are affecting the CPU timings it would be an explanation of what's happening

Can you explain your suggestion below a little further please..

>>Isolate both power supply rails directly back to your power supply
G9, Ixus75


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