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LittleFoot Steppercontroller
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LittleFoot Vpower V4.17A


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With the LittleFoot Controller I do not only present a stepper controller with a competitionless price, i also present a controller with substantially more features then any other controller out there! She proves, also in case of the possible motor current, that efficiency does not have to be expensive! Different to the small LittleFoot, that is also a bit cheaper, the LittleFoot Vpower can be used with all available Steppers. The maximum Motorcurrent of 3 Ampere and the possible Inputvoltage of 35 Volt makes the LittleFoot Vpower to a all-purpose and future-oriented Steppercontroller that leaves no wishes.
I attached particular importance to the fact that the controller is easy to build for self construction, but it is also available as a ready made controller. The suitable motor cables are provided in both cases and do not have to be bought separately!

As the used Firmware is similar to the small LittleFoot (the Configurationssoftware and the Firmwareupdate is identically too.), LittleFoot Vpower has the same features. These are:

  • Microstepping operation in RA and DEC
  • GOTO (speed 20x - 100x) over the LX200 Protocol (optional)
  • Intelligent Tracking with IntellyTrack® (optional)
  • Autoguidinginterface (ST-4 compatible)
  • RS232 (LX200) Autoguiding-Interface
  • Supporting the LX200 PulseGuide Commands
  • 3 Speeds (Siderial/Solar/Lunar)
  • Correction speed smaller then 2x can be configured
  • Backlash compensation in RA and DEC
  • PEC (periodic error correction) with 256 Measurepoints
  • Support of the LX200 focus commands
  • Focus control with the Handcontroller
  • DSLR Control Support for Canon DSLR's
  • LX200 Fan control support
  • Firmware updates send over the serial interface
  • Re-Programmable through out led programming interface
  • Support of all mounts using motorkits up to 3 Ampere
  • Support for the LittleFoot Display Project
  • Inputvoltage from 12V up to 35V

As all my Projects LittleFoot can be ordered as a Selfconstructionkit or a ready made controller. The Plate of the Selfconstructionkit has allready some parts on it because i do not want, that you have to solder those small SMD Parts and there are some extra parts needed to programm the soldered MCU. With the selfconstruction kit it should be easy to construct the Controller if you have some expirience with soldering. If you do not have this knowing, you can order the ready made controller as well.

To configure the Parameter i wrote a small tool that can be downloaded in the Softwaresection. The Gearconfiguration will only take affect after you powered the controller down!
The configuration over the Handcontroller it self is described here.


For Kits and ready made controllers check out the Astromarket!

 

Software and Infos for LittleFoot:

LittleFoot Vpower Current calculator (Win32)

V4 Control from Doug Dieter (Win32)

MCU Configure from Rick Saunders (Linux)

Aspect from Wolfgang Hoffmann (Win32, Linux)

LittleFoot PEC Explorer V1.30 (Win32)

LX200 Tester V1.00 (Win32)

LittleFoot MCU Update V3.40 (Win32)

LittleFoot MCU Update V3.40 (PocketPC)

LX200 Tester from Stefan (Linux)

PocketGuider for PocketPC :-)

LittleFoot Protokoll (PDF)

Documentations!

LittleFoot Handcontroller (JPG)
(The Switchpositions 2x, 8x and 16x showing only the Defaltsettings
and can be configured freely (1,3x - 100x) ;-)

LittleFoot Support-Forum

 

Guidance for the self construction:

The selfconstruction kit includes anything what is needed to successfully build the LittleFoot controller. A Drillingtemplate is included in each kit as well. With a little bit expierence in soldering, there is no problem to build the kit. The MCU is allready programmed, so there is no need for a programmer or other special hardware!



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As i mention above the PCB allready has some parts on it. This has some simple reasons. First i do not want that you have to solder small SMD parts and second there are some extra parts needed to programm the soldered MCU. All future Softwareupdates can be saved easyly over the serial interface.



Click to enlarge

Click to enlarge

The Schematic of LittleFoot shows, LittleFoot is constructed simple and easy. Except the two MCU's there are no special parts on the PCB. The here shown construction steps are just shown as sample. Any other sequence will also end up in success ;-)

At the first step i recommend to solder all parts on top of the PCB. There is nothing special on this side. Just watch IC4 because this MCU is sitting in a socket and on the other side are resistors that must be soldered first!



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Click to enlarge

At the second step all parts on the bottom of the PCB are soldered. There is nothing special to know or watch here as well. Just put the parts in the holes and solder them. IC5 is allready soldered ;-)



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Click to enlarge

If so far everything is fine we can check our soldering once again and get ready to finish the Handcontroller housing. Here we cutout the printed Drillingtemplate and put it in the box.



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Here it is wise to punch the center for the hole and remove the template before drilling. Do not throw the drilling template away because the connection diagramm for some motor connectors is also printed on there ;-)



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On the left side of the housing you have to drill two holes for the power regulators. Here it is usefull to put the PCB in the case and mark the locations of the regulators.



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On the front and lower surface the recess for the connector plugs is filed into the housing. The equipped plate is put for this into the housing and the recess on the plug is adapted. With this work is to be examined it also meaningful whether the direction keys can be operated easily. If this is not the case, the 10mm hole can be adapted with a file accordingly.

The other side of the housing cover is just as simple to work on. I recommend to put the housing halves one on the other and to mark the recesses for the connector plugs. The recess can subsequently, be filed beautifully and adapted to the plugs. For the current supply socket now still another 8mm hole is bored.



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If so far everything is fine and the PCB is sitting well in it's housing, we can solder the wires for the switches and motor cables. This should be done before mounting the PCB in the box. The wires for the switches can look in the sky and will be soldered to the switches after we mount the PCB in his case.

As next step we mount the switches in the case, place the plate in the housing and screw it with the included four screws.



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Now we can connect the switches as shown in the wire diagram.



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Now we can close the case and the construction is done so far. Before we can connect the Motors we need to adjust the Motor current. For this we need the two regulators on the left side and the corresponding pin at the Motor connector. To avoid long calculations I wrote a small windows application that can be downloaded in the Software section. With this small application setting the Motor- and Booster current is a breeze.



To adjust the Motorcurrent we connect a voltmeter and turn the controller on. If you have questions here, please use the Supportforum! With the Current calculator we calculate the needed voltage and adjust the voltage with the Powerregulator at Pin 3. To adjust the Booster current we switch the Speedswitch to 16x. If we press a direction button now the voltage at Pin 3 will increase and we can adjust this voltage with the Boosterregulator. That’s it.

The connectors for the motors can differ from modell to modell. The connection diagram for the 9pol. Motorconnector is described below.

 

Fronttemplate for the LittleFoot:

The last finish for the LittleFoot comes from Zernie who created this Template!



You can download the Template and print it out ;-)

That's it, now i only have to wish a lot of fun with the LittleFoot Steppercontroller :-)

 

Handbox Menus:

In order to be able to configure and control parts of the functionality with the hand controller, i programmed a second processor in the handbox .

I tried to avoid the green LED and like that this LED is only active in the PEC training.

The LED color conditions:

Red on = PEC active

Red off = PEC deactivated

Orange on = Key pressed

Orange blinking = menu

Green blinking 10s = PEC Training begins

Green on = PEC Training running

The software in the handpaddle has 3 menus. These can be activated over the switch (2x = menu 1, 8x = menu 2, 16x = menu 3) and the simultaneous press of all four direction keys. The LED flashes then 1x, 2x or 3x briefly. In the menu the direction keys have the following meaning:

Menu 1:

Left = Focus (-)

Right = Focus (+)

Up = Toggle 2x <=> 1.3x

Down = Find Object (see Update Kit Protocoll)

Menu 2:

Left = speed Lunar

Up = speed Siderial

Right = speed Solar

Down = no tracking (terrestial)

Menu 3:

Left = PEC off

Up = Start/Stop PEC Training

Right = PEC on

Down = Invert GOTO DEC direction

If both RA or DEC keys are pressed at the same time, the direction keys are exchanged.

 

Connection allocation of the connetor plug:

connection pin

Meaning

Zeromodem 9pol.

1

Focus (+) +5V

-

2

TxD (Rs232)

2

3

RxD (RS232)

3

4

+5V

-

5

CPU (MOSI) + Focus speed

-

6

CPU (MISO) + Fan control

-

7

CPU (SCK) + User defined

-

8

CPU (Reset)

-

9

GND

5

10

(ST-4 compatible) UP

-

11

(ST-4 compatible) DOWN

-

12

(ST-4 compatible) RIGHT

-

13

(ST-4 compatible) LEFT

-

14

User defined (see Supportforum)

-

15

Focus (-) +5V

-


 

Connection allocation of the Motorconnector:

connection pin

Meaning

1

DEC Motor ( A' )

2

DEC Motor ( B' )

3

Motorcurrent Adjustment

4

RA Motor ( A' )

5

RA Motor ( B )

6

DEC Motor ( A )

7

DEC Motor ( B )

8

RA Motor ( B' )

9

RA Motor ( A )

Housing

GND



Too good lastly still the sayings, without which it unfortunately sometimes comes in our constitutional state to misunderstandings:
The structural drawings veroeffenlichten by me, plates etc. are freely reproductionable for private users. A commercial marketing of devices to these structural drawings to attribute are, is permitted only with expressly written permission. Reproduction and application to own danger. For function and/or for possible damage, which due to reproductions, which from me publish structural drawings, plates etc. result in, I do not take over myself any responsibility! That sounds itself badly, is however half so wild (with me everything functions perfectly). I have only no desire me for a damage to answer for, only because someone has from such things no notion, a Akku short circuit and the hut or other absengelt.



Copyright © 2004 by Anand Rajiva , E-Mail: LittleFoot@rajiva.de


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