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Old Feb 19, 2003, 09:39 PM
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Servo Tester/Exerciser: Yet another hack

For those of you that like PIC microcontroller projects, I just posted a new one that may interest you. It's the RCST, an R/C Servo Tester.

This pocket sized device is perfect for checking and testing your servos. It features digital accuracy and convenient features, including a servo exercise mode.

Full Details: CLICK ME!

Cost to build it are WELL under $10 for those of you that have a PIC programmer. For those of you that do not have a programmer -- well, here is yet another reason to build, buy, or borrow one

Regards,
Mr. RC-CAM
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Old Feb 20, 2003, 01:32 PM
Official Old Git!
Hampshire, UK
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Mr RC-CAM,

Brill! You keep giving us good things to build (good job I bought a number of PICs!)

Looks like I'll have to build this one as well!

Are you snowed in at the moment and can't fly, so are generating these goodies to fill in your time!

Thanks,

Keep up the good work!
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Old Feb 20, 2003, 01:50 PM
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Quote:
Are you snowed in at the moment and can't fly, so are generating these goodies to fill in your time!
Actually, I created it to simplify the testing of the digital cameras I have been modifying for eZoner's. The Servo tester has helped out a lot, especially since it seriously reduced the clutter from the work bench. The tester is only a couple inches square, which is much smaller than my JR Tx that used to sit in its place.

The weather has been nice lately. As soon as I get caught up I will make an effort to take advantage of it! But for those of you stuck in snow drifts, this project is something that you can build in a couple hours at very low cost. Here is what my first prototype looks like:
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Old Feb 22, 2003, 02:42 PM
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Mr.RC-CAM

I'm in the process of ordering the parts to build this GREAT tester of yours and have a few questions.

1. C3-- cap can it be a lower voltage and is it polorized..?

2. the pic of your tester on your site doesn't show the pushputton S1 switch, did you omit the switch--or is it on the bottom?

Would you allow me to build a few of these for some friends if I only charge them component cost, or do you want me to pay you a royality.....?

Thanks for all your great work

Larry
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Old Feb 22, 2003, 05:52 PM
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Quote:
1. C3-- cap can it be a lower voltage and is it polarized?
C3 is a typical mono ceramic decoupling cap. It is not polarized and its value is not critical. On caps C1, C2, and C3, any voltage over 10V is fine.

Cap C1 should be a 2% tolerance part to ensure cooperation with the firmware. You can use a 10% part, but grossly valued parts may not allow for full servo movement. In my case I just measured a couple junk box parts until I found one that was extremely close to 0.1uF.

Quote:
2. The pic of your tester on your site doesn't show the pushbutton S1 switch, did you omit the switch--or is it on the bottom?
The tiny switch I used in the proto is tucked away on the side and does not appear in the photo. The part called out in the BOM is different than what I used (my servo tester was built with "junk" parts at a cost of about $1).

Quote:
Would you allow me to build a few of these for some friends if I only charge them component cost, or do you want me to pay you a royalty?
I appreciate your concern with my PIC code license terms. If you intend to build two or three for your close friends, at your cost, then you have my permission to use the hex file at no charge. If your intent is to go beyond that, then email me with the exact quantity you wish to make and I will determine what you will need to do.

For those that are wondering what this is all about: Basically, my software projects are for personal use only (no-charge license). PIC reproduction beyond that is considered a commercial application, even if you do not make a profit distributing the programmed PIC. Basic details are mentioned in the readme.txt file that is distributed with the firmware and on my web site.

Regards,
Mr. RC-CAM
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Last edited by Mr.RC-CAM; Feb 22, 2003 at 05:54 PM.
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Old Feb 23, 2003, 12:52 AM
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Mr.RC-CAM

Thanks for the info and if I deside to build any for profit I'll let you know.

Larry
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Old Feb 27, 2003, 05:39 PM
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Capacitor C2

Mr.RC-CAM

Hello again,

I just received my parts from Digi-Key and I have a question on the Capacitor C2 PN# P5123----this is a standard Aluminum Radial-lead Electrolic polorizesed.......!

Is this the correct Cap and if I can use it I assume the Neg side of the Cap goes to ground, Is this correct....?

Thanks,

Larry
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Old Feb 27, 2003, 06:30 PM
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Quote:
I assume the Neg side of the Cap goes to ground...
Yes, that is correct.

Please let me know how the project works out for you. Pos/Neg feedback is often helpful.

Mr. RC-CAM
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Old Feb 28, 2003, 10:11 AM
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Thanks, I still have the PIC Programmer to finish.

As soon as I have a working Servo tester I'll post some Pictures and report.

Larry
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Old Mar 02, 2003, 02:23 PM
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Mr.RC-CAM

Hello again,

I have a couple more questions if you don't mind...?

I am new to PIC programming---still learning.

I am using P16Pro S/W to program the PIC's and I'm getting the following error message:

Fuse Failure at 0xFE2 0x2

It doesn,t seem to matter as the first proto type of the Servo tester works just great......!!!

The 5K pot has dead space, about 30 deg on either end, is this correct...?

I down loader the Spec sheet on the PIC's and the operating voltage listed for the PIC shows 3.0-5.5 volts, so is the R3 220 ohm resistor needed...?

How/what did you use to label the heat shrink on you tester?

As I had to order most components 10 at a time I thought I would try and sell the other 8 so I will be sending you an Email to discuss your thoughts.

Thanks,

Larry
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Old Mar 02, 2003, 04:38 PM
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Quote:
I am using P16Pro S/W to program the PIC's and I'm getting the following error message: Fuse Failure at 0xFE2 0x2.
Something odd there -- sounds like a PIC16Pro bug. "0FE2" is not the correct fuse data value. It should be "0002" just as it says it sees.

If you click on the config button, do the fuses choices match the readme file? When you close the programmer's config screen does the Fuse/Prot. data entry now show up correctly as 0002?

Quote:
The 5K pot has dead space, about 30 deg on either end, is this correct...?
In order to allow the use of an affordable 5K pot I had to assume worse case tolerances. As such, the end stop areas of the pot will have no effect.

The "dead" range will vary depending on the pot that was used. However, Full servo timing will be available over all temps, voltages, and tolerances, using this trick. The alternative would have required a Vreg and a more expensive pot. My goal was to keep the component count low.

Quote:
I down loader the Spec sheet on the PIC's and the operating voltage listed for the PIC shows 3.0-5.5 volts, so is the R3 220 ohm resistor needed...?
Actually, the A parts will survive even higher voltages (nearly 7V). But, R3 is not related to that. It is part of a RC filter that ensures that the currents spikes from high torque servos do not affect the pulse timing. Without R2 and C2 some servos may become VERY twitchy.

Quote:
How/what did you use to label the heat shrink on you tester?
I originally used rub-on letters, but that was a lot of work and not recommended. I do not have a good solution to offer (other than using a Sharpie permanent marking pen).

Quote:
As I had to order most components 10 at a time I thought I would try and sell the other 8 so I will be sending you an Email to discuss your thoughts.
OK. I have responded with the license terms.

Regards,
Mr. RC-CAM
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Old Mar 02, 2003, 05:52 PM
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First Prototype

Mr.RC-CAM,

I did check all Fuse settings and there correct, see below:

OSC: IntRC
WDT: off
MCLRE: off
CP: on
ID: 0E10
CKSum: 3AB2

On the Config screen the Code Protect is On.

Here's my first Prototype, I wanted to build with the least amount of jumper wires so I use 1/2 of a Rat Shack #276-150 project board.

Works great.......!

I have attached a photo.

Thanks,

Larry
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Last edited by wwldo; Mar 02, 2003 at 05:56 PM.
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Old Mar 02, 2003, 06:13 PM
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Quote:
I did check all Fuse settings and they're correct.
Very odd. I just tried the PICPro S/W that you are using (I don't have their programmer, but the software was an easy download). After loading the hex I see that it starts off by reporting the odd FE2 fuse data value. But when I enter and then immediately exit (click'd OK) the Config function the value changes all on its own to 02. Which is just as it should be.

Sounds like a PICPro programmer bug to me. The good news is that all is OK in your programmed part.

RC-CAM
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Old Nov 19, 2004, 01:11 AM
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Chicago
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Thanks for the cool project, MR. RC-Cam!!!
Here are a couple of pics of my finished work-took an hour or so to build.
(PS this thread could get more use in DIY forum? )
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Old Nov 19, 2004, 11:52 AM
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UK
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RC-Man, how easy would it be to port the code to a 12F675 ??
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