RedBitOne - Tiny But Powerful




Introduction: RedBitOne - Tiny But Powerful

About: One man electronic band

A tiny atmega328p-au breakout with all the power of the Arduino(TM) UNO, see it driving your next micro project!

Visit the Blog and take part in a poll about a 10$AVRisp!

OPEN SOURCE --- all files are at THE GITHUB

feel free to use the schematic! its pretty basic but it's designed to be made into a tiny board and the kit contains the board and parts all in one package!

Available as a kit or fully assembled device from My Tindie Store with all specs and capabilities listed there. This will serve as assembly instructions and programming instructions so for the Kit continue with the assembly on the following pages and for a pre assembled model please skip to "Programming"

From ""

Designed to be squeezed into the tiniest of projects where space is key, but as powerful as an Arduino(TM) UNO running on the same chip. At heart its an Atmega328p-AU breakout board with 0.1" spacing, the most basic support circuitry and an isp port for programming. This allows it to be hackable and to adapt, power it with any voltage from 2.7-5.5V! it will (probably) survive and keep going! change the fuse bits! mess with the clock! then stuff it into a tiny enclosure and watch it drive your tiny robot!


So to program this you need and ISP programmer BUT - ISP free's up a bunch of possibilities and is much more reliable and faster than talking over serial via a converter (Like the UNO) and both require a programmer to talk to a computer!? why waste your time with serial! taking up two of your pins, valuable Uart ports and Bootloader space... Ugh. I've tried a USB bootloader (eg Adafruit's Pro Trinket ) but that also takes up 2 pins! and the bootloader takes ages to load, with ISP turn it on and you programs off! just like that - no waiting.

ISP programmers used to be expensive, but now there just as easy to get and MORE useful than an ftdi serial adapter! I would recommend the USB tiny ISP, FAbisp both use the same drivers, orUSBasp

And hey! if you haven't got one just send me your code a in INO or HEX and ill put in on there for ya!

What you get

A 1" by 1" board (will fit in breadboard if 2 opposing rows are populated) and will fit in a perfboard

The Atmega328P-au

A 16 MHZ crystal setup

pull-up reset resistor

Built in Power-LED In your choice of colour

plenty 'O headers

All the necessary pins are broken out for your project including reset - the new board has an updated silkscreen with pin functions labeled as well (pictures are of slightly older board)




Fuse Bits-Same as UNO

Voltage-5.5 to 2.7 (no reg. so do what ya want)

Current >15MA

Want anything else? email me for inquiries

It comes as a kit with the chip setup to run at 16MHZ and pre-tested running BLINK on pin 13 but that 0.8mm TQFP can be a pain, so i will assemble it by hand if that's required. Parts are 0805 and the LED is 0603, the Crystal is through hole to make it easy to hand solder. Again if you would like software pre-loaded instead of Blink just throw me a call.

Shipping - orders made before 12 AM GMT will ship before 7:30 GMT that day on all business days. Parts come in small Jiffy padded envelopes with extra bubble wrap - inside antistatic bag with quick reference assemble instructions as well as a checklist and Serial Number. Full assembly instructions will soon be up on but it should be plug and play so for now just give a call if you need help. To program plug into ISP and use >UPLOAD USING PROGRAMMER on Arduino IDE having selected your programmer

Finally stay posted for the Redbit One Pro and the RedISP - an upgrade with a built in ISP and a Tiny AVRisp

Check out The Custom Geek and his "1 square inch" board, similar but it instead uses ftdi.

Thanks for checking me out!

Step 1: Assembly 1 - Check You Have Everything

Make sure everything is there!

  • 1 x PCB 1 x ATMEGA328P-AU
  • 1 x Crystal 16MHZ
  • 1 x 10K - 103
  • 1 x 200R - 201
  • 2 x 18Pf capacitors
  • 1 x LED - R/G/B
  • headers

If anything is missing email me with your serial number and an enquiry

next tools!

heres what you will need

  • Soldering iron with appropriate tip (hoof is recommended)
  • Solder (as fine pitch as you can find)
  • tweezers
  • a pcb holder
  • extra flux
  • solder wick (i recommend soldamop)

and i recommend

  • electrical tape
  • hot air gun

Step 2: Soldering the TQFP-32

Soldering the chips can be tricky but is do-able

Tweezers are used to hold the package and the polarity means the circle in the chips corner should match up with the one shown, Your flux pen will be used a lot so get it ready - use it with gusto whenever reflowing solder as the flux that is in the core has already gone. Use your solder wick to mop up any spills and bridges

- my personal favourite teacher is Dave from the EEVblog and his drag soldering

But really just google TQFP32 soldering and you will find loads of tutorials on soldering, the way you solder it is down to preference. Unfortunately Dave has a thermal pad chip and doesnt need to solder corners to hold the chip in place, so heres another helpful video from The Custom Geek that does the pins individually.

Hes making a similar board that uses FTDI - you can buy it from his shop and dont worry - they look similar but he knows about the REDbit and it's A-OK

Step 3: The Capacitors, Resistors, Led and Crystal

I would recommend soldering the parts in the order above starting with the 0805 resistors and capacitors and led (0605). The resistors and capacitors have no polarity so do wack them on anyway.First tin one pad of each part with of each some solder ideally the pad on your side that uses the iron so reflowing will be easier. Use tweezers to pick up each part and place them on their pads then reflow the solder after adding flux - this will tack the parts in place. Finally solder the other side of the part and hey presto

C1 and C2 are identical and shown on the insert slip (small browner package without marking)

R2 is marked 201 and is 200 ohm for the LED

R1 (moved to allow mounting hole on new models) is 103 and 10K ohms for reset pullup

Crystal is 16MHZ

LED is well, an led, and the smallest - positive goes to board edge

The LED as its 0603 can be quite fiddly and has a polarity shown on the slip that comes with the REDbit. Its also super easy to loose.

Heres a video that explains it well by itsInOurKernel

The crystal has no polarty and is through hole - Ill assume you can solder it if you're attempting a tqfp

Add headers for isp and pins as necessary.

Step 4: Programming

Whether a kit or a pre assembled model the board is setup as an uno and running blink - all models are tested before shipping. To program the board an AVR isp is required - stay tuned on my store for a 12 dollar AVR isp I'm currently working on! but for now a USBtinyisp or AVRISP MK2 or even an uno running the Arduino ISP sketch! simply plug the ISP header (check orientation - dot is pin 1) in to your programmer and write data as an Atmega328p or UNO.

To use the Arduino IDE select your programmer after plugging it in (no need to select port) and then press upload using programmer. (see above)

AVRdude works similarly but use arguments "-c $YOURPROGRAMMER$ -p atmega328p"

Feel free to mess with the fuses but if you brick it i may feel less inclined to send a new one. the Fuses are that of an UNO.

Final Specs-

  • Voltage - 4.5-5.5 volts recommended for 16MHZ operation (lower voltages are overclocking)
  • Current - depends but chip draws very little apart from large IO changes which always cause current spikes
  • Speed - 16MHZ (16 million clocks a second)
  • IO -20 (6 PWM 6 ADC)
  • ALL IO broken out and Reset line
  • Size 1"-1"
  • Fuse bits LOW-0XFF HIGH-0XDE EXTENDED-0X05
  • Anything else? email

Thanks for reading!

Luke Andrews

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    5 Discussions


    5 years ago on Introduction

    One important problem - there are no decoupling capacitors - very big mistake.

    This board is not designed for analog measurement too.

    LED1 on schematics is in wrong direction.

    Red Smoke
    Red Smoke

    Reply 5 years ago

    Hi, sorry to hear your concern. The Led part itself had an issue in eagle but I hope the polarity instructions are clear. For decoupling unless your doing massive IO switching or such it should not be an issue - so far the board hasn't had any issues that it would solve during testing, but if necessary you may be able to scrape the solder mask off the reverse side and add a cap there. I was wondering what your issue was with analog measurements? Aref? The board was designed to be as cheap as possible with minimal circuitry but still be useful.
    Thanks for your concerns, they will be considered during future products.


    Reply 5 years ago on Introduction


    "The board was designed to be as cheap as possible with minimal circuitry but still be useful."

    1. I understand your purpose, but every silicone chips should use decoupling capacitors - its basic of electronics especially if you want to sale your products.

    2. You narrowing analog measurement capabilities. If knowingly, it's OK.

    Regards from Poland.


    5 years ago

    This is a great idea and a great implementation. Thinking how I will use for my next project. Could have used it already for one of my projects have I known about this before.

    Red Smoke
    Red Smoke

    Reply 5 years ago on Introduction

    Thanks, the appreciation means a lot! The design was built upon requirements set by a previous project i worked on that was extremely small, and nothing else fitted the bill. Oh and psst - the code "6B8BC24" will get you an extra 5% off if you choose to use it, but hurry someone else might first!