can't get Servo Controller 28830 to work

Morkatog · 2012-02-09 01:33

hey everyone,

I just recently purchased the Propeller Servo Controller and several servos. I tried to do a test run using the standard PSCI software as I'm still new to the world of servos, but without succes. After having broswed around I couldn't really find any posts that described the similar problem, so here's what I've tried:

I've hooked up the controller to my laptop using a micro usb cable.
Since it was just a test run I've taped / wired 4 batteries together for a total output of 6V, and tested battery power to ensure that they were fully charged.
I've connected the + side to the socket indicated on the controller et vice versa for the - side.
I've connected 2 RS-2 servos to channel 1 and 2 with the following specs:
Opperating Voltage: 4.8 < 6.0 V
Positioning Time: 4.8 V / 6.0 V
0.19 s/60' / 0.17s / 60'
Operating Torque: 4.8 V / 6.0 V
3.2 kg.cm / 3.5 kg.cm
I then started the PSCI software, and switched to the correct port, which I assume is confirmed by the blinking leds.
I've then programmed 3 frames in channel 1 and 2 to get from 1500-2000 leaving all other fields at their default values.

When I click on the start button then I do see the green led blink to indicate the signal is being sent, but nothing else happens. There's no spin, no twich, nothing.
Any thoughts on what I'm doing wrong? Thanks in advance!

Mike G · 2012-02-09 03:04

Welcome to the forums.

Use the verify command to to verify serial connectivity. The command returns the PSC version, see the PSC manual.
Check the baudrate; 2400 or 38k4. 2400 is the default at start up, see the PSC manual
Make sure you set a delay to gave the servos time to reach an angular position
Verify the servo wires are connected properly.

Morkatog · 2012-02-09 05:59

Thanks for the reply Mike.

I've taken a look at the suggestions you've made, but according to the manual to be able to use the commands listed there I would need a Stamp module if I'm not mistaken?
Currently I don't own one. I was under the impression I should be able to send commands over the USB as well?
I've also installed the other propeller software in the hopes that might allow me direct control, but I couldn't find any clear documentation on command syntaxes if you try to make your own .spin files. Can I use these to control the servos without a Stamp addon as well?

I forgot to mention this in my initial post, but I did check the servo wires as well, mine are BRO (orange) which I've connected correspondigly to the BRW as indicated on the board.
I also did get a return value when trying the propeller program and the PSCI program to get the PSC version (1.0) so I suppose that verifies communication as well between the board and my PC.

dbpage · 2012-02-09 06:31

A Stamp module is not needed to control the Parallax Servo Controller (PSC) with a PC via USB using the PSCI software. If File > "Get PSC Version" is working correctly, then the communication between the PSC and PC is working. I assume you have read the "Read Me" file under "Help" on how to use the PSCI controls. Verify that the PSC jumber is IN or OUT to correspond to Channel 0-15 or 16-31 controls as needed. All that's left is to verify the following:
1. The power is connected correctly to the PSC
2. The power and signals are connected correctly between the PSC and servos
3. The PSC servo power switch is turned ON

Mike G · 2012-02-09 08:10

Good point Dennis B. Page... make sure you the PSC setup for channels 0-15. I don't think the Prop PSC has a jumper like the older PSCs. It is software configured - I think.

IIRC, PSC manual has a PSCI overview?

My experience with the PSC issues - it's always configuration or connections. Check and double check.

Duane Degn · 2012-02-09 09:31

For most commands you do need a microcontroller to communicate with the servo controller.

The default program doesn't use ASCII characters as parameter. You can't tell it to use channel #1 with a terminal program since there isn't anything you can type to send a 1.

Until today that is.

Introducing the new improved Servo Controller firmware.

From the comments I added:

*********************
  Changes by Duane Degn, February 9, 2012
  Added the ability to send commands from a PC
  using a terminal window.
  Use zero padded arguments.
  Use two digits for channel number.
  Use one digit to change modes (0 or 1).
  Use four digits for servo position.
  Use two digits for ramp amount.
  Both upper and lower case characters are
  now allowed.
  Example:
  To set servo on channel 3 to middle position with
  a ramp of 24, use:
  !sc03240750
*********************

So now you should be able to send commands to the servo controller from a terminal.

As I mentioned in the comments, you can use either upper or lower case letters in the commands now.

I've done very little testing with it is far. Let me know about any bugs I introduced.

You'll need to place my version in the same folder as the original so the support objects will be found correctly.

Duane Degn · 2012-02-09 09:52

I just saw the PC software that goes with the servo controller.

So Dennis is correct about not needing a microcontroller to use the servo controller.

I haven't tried the software myself.

Publison · 2012-02-09 13:15

Can you move the servos just using the sliders in the PSCI program?

Always worked for me.

Jim

EDIT: Just to be sure, what CPU platform and Operating System are you on?

Morkatog · 2012-02-16 04:21

I wasn't able to try all the suggestions before today due to work and such, but having just given it a shot again, I'm unfortunately still no closer to solving the problem.

Dennis: I assume the power to the PSC is connected correctly, because when I use the standard PSCI software the PSC will blink blue and green when I play around with the sliders. Also I am able to get the PSC version using the program. As indicated in my original post I've also tested the servo's power source beforehand (it's 6V in total btw) and made sure the + is connected to + and same for the -
Does it really matter whether it is set to 0-15 or 16-31 though? since the program can communicate to all those ports anyhow.

Duane: thanks for the file, I'd love to give it a try, but I am still quite new when it comes to the programming side of the controller. Is there any terminal PC software that you could recommend which I would be able to use in conjunction with your fw update that would send the commands over USB?

Publison: I've moved the sliders and can see the leds on the PSC blink as indicated, but nothing happens to the servos. As for my hardware specs: I've tried it on my PC, using windows 7 ultimate, Core 2 Quad Q6600 8GB DDR2 800 Mhz.
On my laptop I also had no succes, which is an early duo core (can't check the exact specs atm as I left my recharger 80 miles away unfortunately) windows 7, and 2GB DDR2 667 MHZ ram.

Everything seems to be working fine except for the communication with the servos, and I agree with Mike that it's usually connection/configuration issues, or rather, that I'd have done something wrong in this case.
So to rule out all errors I've done the following:
I've used the PSCI software to create 2 frames on all 32 channels moving from 2000 in frame 0 to 1000 in frame 1, leaving servo rates and pause at the default of 0.
With my batteries connected from their + to the + indicated on the board (and same for the -) I've tried to connect my servo's BRO (black red orange) to the boards BRW connection, then in reverse order ORB to BRW, and after that I've done the same with the jumper removed. (so 4 different ways)
I've then reversed the + and - poles from batteries in case the + and - were wrongly indicated on the controller and done the same test again.
Still nothing happens. I also checked again that I had enough power on the batteries (6V).

While I don't mind the extra costs of getting a stamp module if it would resolve the problem, I am a bit hesitant to buy it considering that I still haven't got this to work in the first place..

Duane Degn · 2012-02-16 08:59

Morkatog wrote: »

I also checked again that I had enough power on the batteries (6V).

Most of the servo problems I've had and that I've seen on the forum are from the servos not receiving enough current. Just because the batteries are 6V doesn't mean they have enough power.

Usually four freshly charged AA NiMH are enough to power most servos. I've had wall-wart power supplies that can't produce enough current for some servos.

To start with, just have one servo connected to the controller (I don't remember if you're already doing this or not).

When a servo first starts to move, it draws a lot of current. If the servo and Prop are sharing the same battery then often the Prop resets from the dip in voltage caused by the servo stealing the power.

I don't recall if the Servo Controller lets you power the servos and the Prop separately or not. If it does, you should try separate power supplies.

I'll get back to you on software to use with my firmware update. You shouldn't need the update since there is the GUI software (I didn't realize this was available when I wrote the modified firmware).

A Basic Stamp isn't going to solve this problem. Don't buy one unless you want to use it for other purposes too.

Duane Degn · 2012-02-16 09:12

Morkatog wrote: »

I've then reversed the + and - poles from batteries in case the + and - were wrongly indicated on the controller and done the same test again.

I killed a servo a couple of weeks ago reversing the voltage. You might want to check your servos with some RC gear to make sure they still work.

I don't know if this would kill the servo controller board or not.

I meant to ask in my earlier post about the battery you are using. It might help if you describe your battery pack.

Duane Degn · 2012-02-16 11:24

Morkatog wrote: »

Duane: thanks for the file, I'd love to give it a try, but I am still quite new when it comes to the programming side of the controller. Is there any terminal PC software that you could recommend which I would be able to use in conjunction with your fw update that would send the commands over USB?

To program the Propeller you would use the Propeller Tool which is available from Propeller Downloads.

I use the Parallax Serial Terminal (fourth download in above link) as a terminal window to communicate with the Propeller.

As Publison pointed out, you should be able to use PCSI to interface with the servo controller.

dbpage · 2012-02-20 13:46

Does it really matter whether it is set to 0-15 or 16-31 though since the program can communicate to all those ports anyhow.

You are correct. Channels 0-15 or 16-31 are set by the PSCI software. I was thinking of the previously discontinued serial PSC.

can't get Servo Controller 28830 to work

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