A crummy little servo tester and other minutia

The little servo tester
Well, I needed a way to test all of these servos I got from EBay and I decided to spend a little time making a quick and dirty little board for doing that. It uses a PIC12F683 and has a linear pot attached to it. Simple.

Crummy servo tester
Crummy servo tester


Viscometer Board and stuff
I’ve been working on the software for the viscometer. Every function appears to work, at least based on the rudimentary prototype I have currently running. I am working on a scripting system for this device. I could make it just a basic viscometer but, as anyone that knows me, I simply can’t do. Here’s a pic of the working board.
The prototype viscometer board
The prototype viscometer board

An EEPROM file system
After thinking about how to store files appropriately and trying to have a file system that can work easily with 1024B of space, I started coming up with ways of defining a reasonable file system. Here it is.

  • First 2 bytes are settings, things like block size, filename size and special behaviors like for EEPROMS that can only be written to with blocks.also defined is the address size 8b, 16b or 32b
  • Each file in the FAT consists of a name of either 2,4 or 8 bytes. this is determined by the setting.
  • Following the name is one byte detailing the flags such as read-only, archive, and whether it’s open or not.
  • After the filename and attribute byte, are the addresses. These addresses can be 8, 16 or 32 bits, however, an 8 byte address can address something larger, say 2k rather than 256B if you set the block size appropriately. This of course lowers the efficiency of storage space but allows for some growth in the file. The file can have any number of addresses in order to remove time wasted moving stuff around.

Anyways, that’s what I’ve been working on as of late. Fun!

A Drawing of a Servo, for reference.

Well, my servos have all come in for a project I’ve been working on. These ones being some cheap Chinese servos that I picked up off Ebay. Here’s a photo of one of them.

Chinese 9G RC Servo Photo
Chinese 9G RC Servo Photo

Now that I have them I guess I have no excuse in not doing the project, especially since I bought so many of them, despite them being cheap. In starting my project I’ve decided to offer a PDF of a drawing for the servo since I had no idea how big they were or what they would measure until they arrived, thus, if anyone else wants the drawing, they can use the dimensions for their own purposes.
Here are a couple of pics of the drawing for reference.

Chinese 9G RC Servo drawing
Chinese 9G RC Servo drawing
Chinese 9G RC Servo Solid
Chinese 9G RC Servo Solid

As the project progresses I’ll review the functionality of the servos. After I had ordered them I had read that they are susceptible to outside interference, especially from the likes of human contact around the housing. From what I read, this made the servo “Freak out”. We’ll see I guess, I’m going to make a standard testbed circuit for testing anyways.

So, anyways, for anyone who wants it the drawing, here’s the PDF

Chinese 9G RC Servo PDF

Hopefully someone will find it useful.