Author Topic: Beta-DMX Servo Controller Project (See first post for specs and features)  (Read 37393 times)

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
For what it's worth, some specs I've measured on the servos I've been testing with. All Hitec servos running continuously with no load.


Servo            Type                Torque       No-Load Current (mA)

HS5945MG     Digital                180           500
HS605MG       HT Analog            94           500  (questionable, noisy servo from crash)
HS5985MG     Digital                180           500
HS55             Sub-Micro             18          150
HS81             Micro                    42          150
HS425BB       Std Analog            57          180


As you can see, you can't necessarily equate torque to power consumption. Although I'm thinking we can probably come up with some "rule of thumb".
« Last Edit: October 14, 2011, by dlhoppe »

Offline RJ

  • Administrator
  • Sr. Member
  • *****
  • Posts: 8507
I use these on my plane are they OK?

You are not allowed to view links. Register or Login

RJ
Innovation beats imitation - and it's more satisfying

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
You are not allowed to view links. Register or Login
I use these on my plane are they OK?

You are not allowed to view links. Register or Login

RJ

I don't see why not. I've never used that line of servo, but they look pretty capable. Are you going to actually spin a real tree?   ;)

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
I understand the 470uf cap is on back-order at Mouser. Here's an alternative: You are not allowed to view links. Register or Login


Offline jess_her

  • Sr. Member
  • ****
  • Posts: 217
Hello Dave
Just been out looking at vixen to control Bobcat Servo board Is there a plungin or add-in for this?
Jess
Only limitations in life is your imagination

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
You are not allowed to view links. Register or Login
Hello Dave
Just been out looking at vixen to control Bobcat Servo board Is there a plungin or add-in for this?
Jess


The servo controller behaves just like any other Lynx DMX controller using the Lynx dongle. The Vixen plugin is really related to the dongle, not the controllers. I'm using the "Entec DMX USB Pro" Plugin.

Hope that clears thing up.


Dave

Offline jess_her

  • Sr. Member
  • ****
  • Posts: 217
Yep Dave thx. I'm using Lynx dongle.   Just to be clear, the Bobcat configuration program will set the software endpoints and rotation of the servos when installing the firmware into the Bobcat. Then in Vixen you would want to set the cell intensity to 128 for servo center  OR what ever the Center value of the programed start and ending value in Bobcat Configuration program.
Thanks you Dave.


Jess
Only limitations in life is your imagination

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
Jess_her,

Those are good questions and I probably didn't do a good job of making that clear. Writing the firmware to the servo controller is the same as any other PIC-based DIY controller. Using the Pickit and writing the hex file to the PIC is the firmware part. That must be done first before you can think about using the config tool. The firmware has special routines that allow it to accept the parameters sent by the config tool. So once the firmware is loaded onto the PIC, you can then use the configuration tool to set the endpoints, direction, channel assignments, etc.

Steps to get up and running:

1. Load firmware to PIC using your Pickit or whatever programmer you have.
2. Test the servo controller with Vixen or any other source of DMX data to make sure the firmware is loaded and functioning correctly.
3. Figure out your end point limits, directions and channel assignments.
4. Use the config tool to send the parameters from step 3 to the servo controller.

Please note, by default the DMX channel assignments are 1-8 for the servos and 9-16 for the LED outputs.


You are correct regarding cell intensity in Vixen. A value of 128 will put the servo in the center of it's range. Well I should say 127 is mid-point between 0 and 255. Although I thought you could only specify intensity as a percentage in Vixen. Is there a way to specify specific values? I haven't seen it, but I'd like to know how to do it if it can be done.

Remember, even though you may specify limited travel range for a given servo channel, you'll still get a full 256 discreet positions as related to the DMX intensity values. The controller will "scale" the servo travel range (as specified by the end points you set with the config tool) across 256 increments. So a DMX intensity value of 0 will correspond to the "Start Value" from the config tool, and 255 will correspond to the "End Value" from the config tool.

Let's walk through a simple example where we'll set the start and end points at 1/4 (start value = 63) and 3/4 (end value = 191) of the full range. The first illustration shows where we would like to have our servo travel start and end (see where 63 and 91 fall on the travel range). We want the low end point to start at the position associated with intensity value 63 (based on default full range). We want the upper end point to be equivalent to the intensity value 91 (also based on the default full range).  The second illustration shows how the servo would behave after configuring those end point values using the config tool.

(servo travel distances are for example purposes only)
                                             
DMX Intensity:                 0.........63..................91........255   
Default Servo end points: |...........................................|      << travel range related to DMX intensity value
                                      |<-------- 1 inch -------------->|      << default travel range (start = 0, end = 255)

DMX Intensity:                           0.....................255             << still get 256 DMX intensity values
Adjusted Servo end points:          |.....................|                 << now scaled across shorter travel range
                                                 |<- 1/2 inch ->|




« Last Edit: October 17, 2011, by dlhoppe »

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
You guys that are setting up "mechanical animation" with this servo controller should think about getting a DMX channel tester when the coop opens. It's the perfect tool for helping you figure out travel end points and direction when designing your display. I don't mean this to come off like a "sales pitch", but I've done enough testing with both devices to see just how well it works with the servo controller for setup, testing and troubleshooting your servo outputs.

Food for thought...

Offline jess_her

  • Sr. Member
  • ****
  • Posts: 217

Thanks Dave


I have been playing around with Vixen, and for those that don't know how to  convert cell value from percent to a number there is a button 3rd from the right on the row (cell on, cell off, ramp on, etc.).  Also the 2nd from the right will display the values in the cell all the time.  Very helpfull at least for me.

Jess
Only limitations in life is your imagination

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
You are not allowed to view links. Register or Login

Thanks Dave


I have been playing around with Vixen, and for those that don't know how to  convert cell value from percent to a number there is a button 3rd from the right on the row (cell on, cell off, ramp on, etc.).  Also the 2nd from the right will display the values in the cell all the time.  Very helpfull at least for me.

Jess

Thanks for that Vixen tip! I looked all over and couldn't find that feature.

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
You are not allowed to view links. Register or Login
Dave
So if the starting point 63 and ending point is 191 set by the configuration program you still get 256 discreet steps with Bobcat servo control?

Jess


Yes, that's correct. See post #112. I edited it to give some details.

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
FYI,

I ordered a couple of power supplies to test:

You are not allowed to view links. Register or Login

AND

You are not allowed to view links. Register or Login


I'll report my test results and offer them to anyone interested at a "demo" price after I'm done with them.   :)
« Last Edit: October 17, 2011, by dlhoppe »

Offline dlhoppe

  • Moderator
  • Sr. Member
  • *****
  • Posts: 261
Completed example.  Notice the diode at position D4 (single power supply configuration).


Offline rrawlings

  • Sr. Member
  • ****
  • Posts: 141
Just waiting for my parts from Mouser, hope to have some feedback to you this time next week if all goes well