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CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD

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Offline ahull

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #270 on: 09 / December / 2012, 04:51:59 »
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Quote from: SticK on 08 / December / 2012, 18:54:35
More news ... I just got ZOOM unstow/stow working :D, so now the only thing left moving on the entire camera is the ZOOM MOTOR shaft (and the SHUTTER of course).  I could take a pic but I'd rather wait until all the mecha is completely gone.  The ZOOM MOTOR encoder dummy will be quite a challenge // it won't be easy at all ???.

I suspect we only need to simulate the fixed number of feedback pulses from the encoder,  so it might not be quite as difficult as it appears  :)... assuming we don't need to simulate/monitor the stall current in the motor  :(.

Timing is everything of course.. so we need a few 'scope traces. :D
« Last Edit: 09 / December / 2012, 04:57:12 by ahull »
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Offline Microfunguy

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #271 on: 09 / December / 2012, 08:41:49 »
I have not read the full specification of the Arduino yet but I notice it has five pulse-width-modulated pins.

Will they be of use in generating a pulse train as the zoom moves ?
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Offline SticK

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #272 on: 09 / December / 2012, 09:36:41 »
@ahull
Quote
so we need a few 'scope traces
Fig1 unstow @ 100 mS/div - (trig on POSITION PI POWER rising edge)
   POSITION PI POWER
   ENCODER PI POWER
   Front ENC PI phototransistor
   Back ENC PI phototransistor
 Fig 2 unstow @ 5 mS/div - (trig on POSITION PI POWER rising edge)
   ENCODER PI POWER
   Front ENC PI phototransistor
   Back ENC PI phototransistor

@ahull
Quote
I suspect we only need to simulate the fixed number of feedback pulses from the encoder
I got this data last night.  The motor has two sensors at 120deg apart axially.  The number of pulses are 420 in unstow and stow, in ~660 mS.  The equal number in both directions suggests that probably anti-backlash is not applied on the ZOOM subassembly during these two events, one critical potential stumbling block I was concerned about.  The other concern is inertia.   You can definitely see it (Fig 2), but the real shot-in-the-dark is whether FW measures it or not.  If that is being detected, I don't expect we'll have enough MIPS available to simulate.  So I will begin without inertia and see if Canon complains.  The phase shift may be important too, creating possible extra CPU expense.

@ahull
Quote
assuming we don't need to simulate/monitor the stall current in the motor
A real possibility too, but I don't expect so // it would be overkill for them to detect stall current when all can be done with the axial sensors.  Also, if there is anti-backlash, motor direction will likely have to be detected by the microcontroller and simulated, but we really be sure yet.  As I said, it's not simple ???.

@Microfunguy
Quote
I have not read the full specification of the Arduino yet but I notice it has five pulse-width-modulated pins.  Will they be of use in generating a pulse train as the zoom moves ?
That's the first thing I looked at.  From what I understand ... the base frequency has to be a power-of-2, and that will likely not fit the solution requirement.  So it looks like we'll have to synthesize it ourselves :(.  Ideas are welcome!
« Last Edit: 09 / December / 2012, 09:52:35 by SticK »
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Offline Microfunguy

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #273 on: 09 / December / 2012, 09:51:04 »
research 'picaxe' OR 'arduino' AND 'bit banging'
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Offline Microfunguy

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #274 on: 09 / December / 2012, 09:53:42 »
Well, the zoom motor is expected to work at a certain speed if it is not obstructed and a certain number of pulses are expected.
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Offline SticK

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #275 on: 09 / December / 2012, 11:30:37 »
@Microfunguy
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Well, the zoom motor is expected to work at a certain speed if it is not obstructed and a certain number of pulses are expected
Right now, by removing a gear, the ZOOM MOTOR is unloaded and the lens position vane is permanently obstructing the POSITION ZOOM PI (ZOOM assembly does not move but the motor shaft does).  Because the ZOOM POSITION PI (like the FOCUS POSITION PI) cannot be disconnected without cutting the ribbon cables, the uC driving pin is in parallel with the phototransistor, a safe driving condition when the PI is obstructed.  The other two dummies (IRIS & FOCUS) still work so having changed the speed of the motor a bit due removing the load does not adversely affect overall dummy operation (IRIS & FOCUS timings did not have to be changed).  That is good news of course because it suggests there is some slop to wade around in.  So I think fundamentally, the 420 pulses are reliable and can be coded into the uC (w/o regard to inertia effects for now), into that 660 mS window.  That's where we can start.

edit:
The hope is that the Canon uC is detecting ZOOM ENCODER PI signalling by interrupt-counting rather than by looking for an expectant temporal window on each pulse.  The former would be easier and more CPU-efficient to solve.
« Last Edit: 09 / December / 2012, 11:56:35 by SticK »
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Offline Microfunguy

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #276 on: 09 / December / 2012, 11:59:47 »
Any experience of this 'scope, they are meant to be good value and even hackable ?  :-

Ebay # 280915462875
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Offline ahull

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #277 on: 09 / December / 2012, 17:11:59 »
Quote from: Microfunguy on 09 / December / 2012, 11:59:47
Any experience of this 'scope, they are meant to be good value and even hackable ?  :-

Ebay # 280915462875

No experience of that particular scope but... does it hack...

http://hackaday.com/2012/10/10/giving-the-rygol-ds1052e-scope-a-spectrum-analyzer/

... back on topic, we need to get stuck in to timer logic here. Lots of info about this on the interweb, but this is a good place to start.... http://letsmakerobots.com/node/28278

« Last Edit: 09 / December / 2012, 17:17:20 by ahull »
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Offline SticK

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #278 on: 09 / December / 2012, 17:44:54 »
@ahull
Nice informative hit on the Diecimila.  The issue is to match and figure out which timers on the ATMega32U4 chip (SparkFun Pro Micro) can be used and what the syntax correlations are.  Timer0 is probably the same should be reserved for the standard delay and time functions.  Here's another site I've been reading ....
http://www.mythic-beasts.com/~markt/ATmega-timers.html
« Last Edit: 09 / December / 2012, 17:46:57 by SticK »
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Offline Microfunguy

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Re: CHDKPTP: S90 Primary Focal Plane Configuration - hacking out the CCD
« Reply #279 on: 09 / December / 2012, 18:26:07 »
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