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16mhz - 8mhz Microduino Conversion

Generally, when we talk about processors, most people have heard of over clocking. What that means is to basically make the chip do more execution cycles per second. The tradeoff is generally more power demand and a byproduct is more heat. That's where you see creative cooling designs (Liquid cooling) and larger power supplies.

We're going to do the opposite. To save on power demands, and to enable the Microduino to run off of 3V3 reliably, we're going to "slow down" the processor. The manufactures of Microduino have plans to release the 8MHZ versions sometime in the future, and some Kickstarters apparently got early versions. The rest of us, have to modify the 16MHZ to 8MHZ. Luckily, Microduino already has the boot loader code for the 8MHZ version available, making our jobs a lot simpler.

The Conversion Schematic:

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Parts

16mhz Microduino Core+ - Microduino
8mhz Resonator Chip - 8mhz resonator
Wire - any wire should do. About 2 - 3 mm

Tools

Soldering Iron with variable tempature
Solder
Flux
pliers
small screwdriver
OPTIONAL: Solder Re-work station

Step 1: Switch Power Jumpers

The Microduino board was meant to operate in both 8MHZ and 16MHZ. The first part of the change requires de-soldering the resistor jumper on the 5V connection, and connecting the 3V3 jumper. Boards like this use a resistor with basically 0 ohms. It's a common way to do surface mount jump connections instead of costume copper etching.

Switching Jumpers

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a.) de-solder resistor jumper

b.) use a small piece of wire to connect the 3V3 jumper

I chose to use a wire instead of reusing the resistor. In early boards I used, I often damaged the surface mount resistor on removal making it unreliable to be used again. Since the resistor is really 0 resistance, a direct wire connection will do the job just as well.

In placing the wire jumper, use flux to help with the soldering process.

c.) test your connections

Simply use a continuity tester to make sure the 3V3 pin is connected to the other end of the 3V3 jumper.

Testing Connection

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Step 2: Switch the Resonator

a.) Use pliers to remove as much of the resonator as possible

You will be "destroying the old resonator". The top section will come of fairly easily. I chose to do this before using the soldering iron to make that stage easier. It's harder to get to the solder pads without breaking off as much of the resonator as you can.

Resonator Removal

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b.) Use soldering iron to clean 3 pads

The Resonator has 3 connection points. Use a soldering iron co clean off the remaining debris from the 3 pads. You may need to use a solder sucker to clean them up a bit.

c.) re-apply solder to pads

Use flux! Make sure you don't join the 3 pads at all. Chances are you have removed too much solder in previous steps. Hence the need to re-apply.

d.) Place 8mhz resonator

resonators will come up a "cut tape" format. Use an ex-acto knife to cut one out. Now align the resonator with the 3 pads. I found it useful offsetting the resonator slightly towards the corner. This provides points of contact with the solder pads and your soldering iron.

Resonator Replacement

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e.) Solder 8mhz Resonator

Use the tip of the soldering iron to melt each pad. Use a set of pliers or a small screwdriver to press down on the resonator. Work back and fourth until the resonator is secured with all 3 pads. Make sure none of the solder pads connect with the metal top of the resonator. This will make it non-functional.

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Do not create a short on the pads or connect the pads to the resonator top! This will prevent the resonator from working at all!

Step 3: Burn 8Mhz boot loader

Resonator Replacement

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I prefer to use a Arduino Uno to program it. Luckily Microduino describes these steps at the following link:

Burning 8mhz Bootloader to Microduino

Programming Success

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Completed Module

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Now, your all good to go! This little module is great in general for various small form, low power projects, especially when paired with an Bluetooth LE!

The Build