Design Decision

Side Project:

I am moving forward with the Compass toy prototyping.  I am designing a simple breakout PCB for testing the display. I may put the display breakout for sale on Tindie.

Project Intent:

The primary goal of this project/blog is to show electronics design start to finish.

The design goal is an inexpensive in circuit chip programmer that will work for most devices available.


The Raspberry Pi Zero was released November of 2015 at a price of $5 US each.  I even got one with a copy of MagPi.  To Make it run any code at all, it needs a power supply and microSD card.

Of course I could continue with the current design.

Common components:

Both the Raspberry Pi and the current design need the following components.

Printed Circuit Board
Battery for power supply and charging circuit
Vpp Supply
Level Shifter Circuit
External ADC(Still undecided for current design)
USB to serial Bridge (not sure it’s necessary for R Pi)

Additional components for Raspberry Pi:

WiFi Dongle
Stacking header pins
microSD Card

Additional components for current Design:

SPI RAM (maybe able to drop from design)

Significant Differences:

Both solutions have their merits.  The differences that matter are price and memory.  Of course I want to keep the price down.  Selling a daughter board without the Rasperry PI zero to make the price look better is not good business.  The Raspberry Pi solution is more expensive.

The Raspberry Pi has a lot more RAM and essentially unlimited program space.  This makes developing the software much easier.  It’s also nice that it has more IO pins available.  Developing firmware for the ESP-12F is harder.

The decision:

Harder is not necessarily bad.  There is a cost to harder, It will take me longer to finish. On the other hand, I’ll have to become a better software/firmware developer.

The ESP8266 work I have blogged about has brought a significant number of readers to this blog.

I have decided to continue with the current design.  I expect some, maybe a lot of future posts will be about working through online tutorials to improve my coding skills.


If you read this blog regularly, I would love to hear from you.  What is your opinion for moving forward?

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