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The Overdrive

What do you do when your project runs out of horsepower?
Well you increase them of course.

The Uno/Dumilanove Overdrive, running at 32MHz, makes your board and project go twice as fast.

It replaces the existing crystal with a clockgen running at 32MHz for twice the speed.

And it's 100% compatible and 200% the speed.

That is a real speed upgrade.

The Red Devil

Why a clock generator?

Because using a crystal at 32MHz won't work on the ATmega.
Being spec to 20MHz It just doesn't oscillate at 32MHz.

But a clockgen will force it to clock with is high output swing.
So it runs.

There is a drawback,

It won't work at +70deg anymore.
So don't use it in a car application.

Needed changes

For the timing to be correct you need to add a setting to the Boards.txt file in the ArduinoIDE.

##############################################################

uno.name=Arduino Uno Turbo
uno.upload.tool=avrdude
uno.upload.protocol=arduino
uno.upload.maximum_size=32256
uno.upload.maximum_data_size=2048
uno.upload.speed=230400 #For the original Uno chip use this
#uno.upload.speed=115200   #For the Adaboot 328 chip use this one.

uno.bootloader.tool=avrdude
uno.bootloader.low_fuses=0xFF
uno.bootloader.high_fuses=0xDE
uno.bootloader.extended_fuses=0x05
uno.bootloader.unlock_bits=0x3F
uno.bootloader.lock_bits=0x0F
uno.bootloader.file=optiboot/optiboot_atmega328.hex

uno.build.mcu=atmega328p
uno.build.f_cpu=32000000L
uno.build.board=AVR_UNO
uno.build.core=arduino
uno.build.variant=standard

##############################################################

The turbocharger

How?

The Uno/Dumilanove is set to use a fullswing external oscillator.
That's a good thing because we can force the internal clock circuitry to run with our own TTL-signal. 

We disconnect the Xtal1 and Xtal2 pins from the onboard crystal and feed our rail-to-rail 32MHz signal to the Xtal1 pin.
The Xtal2 pin is left unconnected.

Cut both the Xtal1 and 2 pins to the circuitboard because the crystal and capacitors will act as a filter on our new clocksignal.

Schematics

dahans
dahans

What Clock Gen are you using?

3 months ago
Jan Ostman
Jan Ostman

It's a standard 8-pin TTL chip. Anyone works

3 months ago

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The UNO Overdrive

The UNO Overdrive

by Jan Ostman

What to do when your Uno isn't fast enough


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