TheBackShed.com

Forum Index : Microcontroller and PC projects : Pull-A-Mite!

Author

Message

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9586

Posted: 04:14pm 23 Dec 2014

Copy link to clipboard

Print this post

Now that I have finished my Christmas shopping hell, I set about designing a small PCB layout for I/O use with the Micromite:

It was designed for the Micromite, but could be used with any MCU, really.

Any of the 8 I/O pins can be pulled up or down as required via the tri-state DIL switch. Therefore, you can have some pins as pull-up, and others as pull-down, all on the one board without having to fuff around with breadboard resistors.

You can also leave the switch in the zero position and there will be no pull-up or pull-down of any kind. All pins to the Micromite(or other MCU) have series 1k resistors for current limiting reasons a-la the standard 1k/10k pull-up or pull-down arrangement. The DIL tri-state switch can be had from element14 for US$1.60 each.

I also included a couple of 4k7's for I2C work - that takes them off the breadboard too when playing around with I2C modules. Switches 9 and 10 on the DIL are just pass-thru switches, so either 9 or 10 can be either high, low or floating(off). The switch itself has a rating of 2000 cycles, which should be MORE then enough for bench testing, and if it does finally give up, you can replace the switch easily as the board is single-sided, and it only costs one buck sixty. Like most DIL switches though, it is not a high-current device, and is rated for 25mA per pole, so suitable for pull-up/pull-down switching, but not for switching power to that 10W LED module!

All through-hole - NO SMD for anyone to worry about, and single-sided PCB so you could etch this at home if you wanted.

If there is any interest past this post, let me know, and I will prepare and upload all Gerber files/drill files etc. Using Shenzhen's PCB service, you can get 10 of these boards for $8.90, so I don't know if there is anyone who would bother to etch/drill/lacquer their own these days with those sorts of prices, but you never know.

Smoke makes things work. When the smoke gets out, it stops!

mindrobots
Newbie

Joined: 21/05/2014
Location: United States
Posts: 32

Posted: 08:01am 26 Dec 2014

Copy link to clipboard

Print this post

Grogster,

These sure look useful for clearing off breadboard real estate when prototyping. If you provide the files, I'll order a set or two from China for personal use and for my U.S. friends.

Great idea!

What are pins 9 and 10? (It's not clear to me - may just need more coffee!)

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9586

Posted: 01:36pm 26 Dec 2014

Copy link to clipboard

Print this post

Hey there - will upload a ZIP later today. I will make it a 10x10 panel, as Shenzhen can make these boards with V-grooving - four boards per panel, so you will get 40 of these pull-a-mite boards for a whopping US$9.90..... Credit must go to Mick(bigmik) for his help via PM with the V-grooving idea for panelizing the design for maximum boards for your buck.

Pins 9 and 10 were spare on the tri-state switch, so they are just pass-thru. Useful to simulate a switch action. They can be either high or low or off.

Here is the tri-state DIL switch. This is the New Zealand branch of element14, but if you take the part #, and plug that into the US element14, I would expect it to come back with the same switch.

Smoke makes things work. When the smoke gets out, it stops!

Grogster

Admin Group

Joined: 31/12/2012
Location: New Zealand
Posts: 9586

Posted: 09:52pm 26 Dec 2014

Copy link to clipboard

Print this post

Hi folks.

Here is the ZIP file of all the gerbers and the excellon drill data.
Pretty much any PCB house should be able to work with these, but you may need to tell them that this is a single-sided board.

2014-12-27_074753_Pull-A-Mite_1A.zip

These files are for a 10x10 panel, with four separate boards per panel.
The outline gerber includes the v-grooving information, and most PCB houses will do the v-grooving for you, but some will not. Shenzhen do, and they are my new favourite PCB house. The V-grooving is fantastic, as you can then just snap the boards out of the panel without having to cut the panel up and sand the edges square.

EDIT: Here is a GIF of the panel:

Edited by Grogster 2014-12-28

Smoke makes things work. When the smoke gets out, it stops!

Print this page

To reply to this topic, you need to log in.