LED Visor, MSP430 (Schematic Capture, Layout)

This post is the second in a multi-post set: 

• LED Visor, MSP430 (Concept)
• LED Visor, MSP430 (Schematic Capture, Layout)
• LED Visor, MSP430 (Software) 
• LED Visor, MSP430 (Final Build into Visor) 

Having decided on a schematic, I then went ahead and installed KiCad. While it's outside the scope of this write up, I needed to create a few custom parts in order to get this to work. If you want to do this, I'd suggest following the write up on the CuriousInventor.com found  here.

I had now gone from this:

To This:

Parts List is as follows (with links to digitkey):

• D1,D3,D5,D7 : 5MM LED Purple. ($1.39 ea)
• D2,D4,D6,D8: 5MM LED White. ($0.43 ea)
• U1: 3.5V LDO regulator. ($0.66 ea)
• U2 : CAT4008 LED Driver. ( $1.75 ea)
• U3: Header, Male part  for connecting the ez430 target board to the PCB ($1.48 ea)
• U3: Header, Female part (1.09 ea)
• (connects to U3) : EZ430-F2012 target boards. ( $10.20, pack of 3 target boards)
  
• R1 : 6.19K ohms 1/10 W resistor. ($0.67 ea)
• R2,R3: 100K ohm resistor. ( $0.02 ea)
• Battery Holder 4 x AAA batteries ($1.27 ea)
• C1,C2: 100uF cap. ($0.79 ea)
• C3: 1.0 uF 10V, Y5V Cap. ($0.79 ea)
• SW1,SW2 : Switches.  ($.12 ea)

With Schematic capture complete, I moved onto layout. I wanted to try and keep my PCB small, so it would fit in a hat, tie or visor. I decided on about 2 inches by 1.5 inches.

The layout took me about two days, though a good part of that time was getting used to the tool. I had used professional layout software before, so the process was familiar. 

One of the cool features of KiCad is the ability to render a PCB in 3D. In order to do this, I had to install Wings3D.

The last step was packaging up the data for BatchPCB. I found some info in the sparkFun form, which I used to setup my own file.

My settings were as follows:

• Drill Units: Inches
• Decimal Format: Suppress Leading Zeros
• Precision: 2:4      
• Drill Origin: Absolute
• Drill Sheet: None
• Drill Report: None
• HPGL Plotter Options: 20cm/s - Pen Number 1
• Mirror Y Access: Unchecked
• Minimal Header: Checked

I then created the collection of files need (copper layer top, copper layer bottom, silkscreen top, mask top, mask bottom, components) as documented by batchPCB and uploaded them.

In a few hours, I got an e-mail back that I'd passes the automated test, and I ordered 3 PCBs. 16 days later I received my PCBs!

LED Visor, MSP430 (Concept)

This post is the first in a multi-post set: 

• LED Visor, MSP430 (Concept)
• LED Visor, MSP430 (Schematic Capture, Layout)
• LED Visor, MSP430 (Software) 
• LED Visor, MSP430 (Final Build into Visor) 

This project actually came before the LED jacket. It also was an experiment to try and see what the process would be like to work with the MSP430 development system at home. I've developed several professional products for the MSP430, but all of them used big expensive compilers with the pcb layout done by our layout team.

Design

 First off, I decided I wanted to put some LEDs on a hat or visor. This made for a nice, trivial project.

I had a ez430-F2013 which I'd picked up from work . It wasn't quite what we needed at work, however it was just fine for a small home project. If your interested, you can pick one up from digikey for about $20.

ez430-F2013 Programmer & dev board.

I also was interested in trying out two new tools.

• One was a PCB EDA tool, KiCad. While I know that a lot of folks like Eagle,  I wanted something that was open source. After looking at gEDA, I decided I would rater use something a little more integrated.
• I wanted to try out BatchPCB, a service which fabricates custom circuit boards. While the wait times can be long, the price was right. I wanted to see if I could take a circuit idea from schematic capture, to layout, to reality. 

For my PCB I need to :

• Provide a power source (e.g. power regulation)
• Provide a circuit for driving the LEDs.
• Provide a way to connect up the ez430 development board.
• Provide a way to control the LEDs.

After some browsing around on digikey, I found the CAT4008 LED driver. It was a nice, low cost, simple to use LED driver so I picked it.

The TI MSP430F2013 can run from 1.8V to 3.6V. For this project, I decided I wanted a 3.5V regulator. After some looking, I picked a small 3.5V 600mA regulator.

I drew up a circuit by hand in my lab notebook, using the reference information in the datasheets for parts I'd selected.

Notebook pre-plan for circuit.

Next: PCB Schematic Capture and Layout.