Prototyping Boards

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I'm old school and still build prototypes (as well as designing my code on paper first). Most of my stuff is more than just an 'Arduino + Shield' so I tend to end up hanging a prototype board onto an Arduino, or stuffing a Nano onto a prototype board. I also use some of these as almost disposable prototypes...

 

 

It's a useful little board but sometimes a bit small. As is the Arduino prototype board.

 

So I'm thinking of making my own and wondered what features I may have missed. So far I have...

 

mega328 in DIP

DC input jack

USB (power only) jack

2-way screw terminal for DC input

Aref capacitor

on-board 5V or 3V3 regulator (likely switching using a Recom part)

6-pin (FTDI) SIL header with DTR reset capacitor

6-pin AVR ISP connector

Prototype area with power busses

Easy access to all AVR IO pins

Crystal and capacitors

Area tracked for IDC ribbon 'output' connectors

Probably eurocard sized (160mm x 100mm) plus eurocard mounting holes

Area tracked for screw terminals

Unallocated buss lines for other power rails

 

Can anyone think of any other useful general purpose features?

 

I also wondered about doing an SMT version for the new 4809 as a second-gen Arduino version.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

Last Edited: Wed. Aug 15, 2018 - 08:45 AM
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- One or more unallocated LEDs with series Rs

- Decoupling caps for your M328

- unallocated N channel mosfet for external relay drive

- test pins

- links in supply lines for measuring current consumption

- buzzer perhaps (with mosfet driver)

- RS485 driver (maybe)

- (G)LCD connections

IR transmitter/receiver devices (unallocated)

- unallocated trimpot (maybe to simulate analogue input)

- op amp (if you are into analogue)

- provision for I2C bus

 

 

 

Ross McKenzie ValuSoft Melbourne Australia

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Brian Fairchild wrote:
I'm old school and still build prototypes (as well as designing my code on paper first).

Likewise.

 

The trouble I always find with commercial "development" boards is that they try to cram too much stuff on - which ends up just getting in the way of what I need to do.

 

Therefore I like Ross's idea of the unallocated extras - so you can easily connect them if you need them, but they don't get in the way when you don't.

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Brian Fairchild wrote:
I'm old school and still build prototypes (as well as designing my code on paper first). Most of my stuff is more than just an 'Arduino + Shield' so I tend to end up hanging a prototype board onto an Arduino, or stuffing a Nano onto a prototype board. I also use some of these as almost disposable prototypes...

 

I build things on Arduino Protoshield pcb.   The green pcbs on Ebay are better than the official Blue pcbs.   A Mega Protoshield has more area than a Uno one.

 

You can stack Shields if you run out of space.   

I also solder breadboardable modules like BluePill or ESP32 onto a Protoshield.   Then I can attach other Protoshields.

 

Alternatively,  I put Arduino headers onto a regular large Protoboard.   (I have to crank the D8-D13 header to fit the 2.54mm matrix)

 

I still have several traditional dev boards that are useful for their "built-in" RS232, 7-seg, LEDs, LCD header, GLCD header, ...

 

Quite honestly,   Arduino format boards with onboard debugger  are a lot more convenient than dev board + power + debugger + trailing cables + ...

e.g. Zero, Nucleo, FRDM, ... need one USB cable.   ( + shield containing external electronics)

 

It is all a question of personal choice.    YMMV.

 

David.

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Brian Fairchild wrote:
Area tracked for IDC ribbon 'output' connectors
fyi, solderless IDC connectors :

https://www.mouser.com/new/Wurth-Electronics/wurth-redfit-idc-skedd/

The connector's lifetime is limited to 25 mating cycles for bench use (10 mating cycles for field use)

Brian Fairchild wrote:
I also wondered about doing an SMT version for the new 4809 as a second-gen Arduino version.
BusBoard has a mega1284 eurocard board.

http://www.busboard.com/microcontroller

Would be interested in a mega4809 with 1.27mm pitch SMD pads for the proto area.

 

"Dare to be naïve." - Buckminster Fuller

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A few leds should always be included, add header pins to them so you can jumper them to wherever you need.  Maybe 2 switches should also always be included, with a connection header.  A pot was also mentioned.

Or perhaps you prefer to solder in everything you want & have no excess---its a tradeoff.

 

Polyswitch (or fuse) on power input

 

Perhaps define a spot for a secondary regulator (diodes,reg & caps)---in case not everything runs at the same voltage (ex: feed in 15V, regulate 12V & 5V,  feed in 12v regulate 9V & 3.3V )

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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david.prentice wrote:
The green pcbs on Ebay are better than the official Blue pcbs.

Thanks for the hint David, also found some nano to uno boards on Ebay as well.

Now the wait for china shipping. sad

 

Jim

 

Click Link: Get Free Stock: Retire early! PM for strategy

share.robinhood.com/jamesc3274
https://www.onegold.com/join/7134f67c2b814c5ca8144a458eccfd61

 

 

 

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gchapman wrote:

BusBoard has a mega1284 eurocard board.

http://www.busboard.com/microcontroller

 

Thanks, I did wonder about doing a 1284 version. That one probably has too much dedicated stuff on it and not enough 'sea of pads'.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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avrcandies wrote:
Polyswitch (or fuse) on power input
or PolyZen (PolySwitch on Zener diode)

If Brian selects the Recom SMPS and it's 24V SLA battery for an electrical power source then it's PolySwitch (PolyZen is 16V max for one model)

PolyZen can get hot (a few watts)

https://www.littelfuse.com/products/polyzen-devices.aspx

avrcandies wrote:
Perhaps define a spot for a secondary regulator ...
Yes though a significant amount of analog can be on a 24V SLA; a relative few JFET op amps are 10V max.

3.3V is popular for cellular, Wi-Fi, LoRa, Bluetooth, and Ethernet modules.

Low noise regulators aren't a requirement or a need for both primary and secondary regulators.

IIRC, there's no EMC requirement for an evaluation board's regulators.

 

"Dare to be naïve." - Buckminster Fuller

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Brian Fairchild wrote:
I also wondered about doing an SMT version for the new 4809 as a second-gen Arduino version.

 

Maybe a more incremental improvement would be the Mega328PB. The 4809 is very different from a 328P.

Last Edited: Wed. Aug 15, 2018 - 05:11 PM
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Don't forget the 0.1 uF cap and 10uH inductor on the AVCC pin for noise cancellation as shown in the Analog Noise Canceling Techniques section of the ATmega328P data sheet.

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valusoft wrote:

- Decoupling caps for your M328

 

 

MarkThomas wrote:

Don't forget the 0.1 uF cap and 10uH inductor on the AVCC pin for noise cancellation...

 

All my designs follow the letter of the Atmel 'How To..." App Notes.

#1 This forum helps those that help themselves

#2 All grounds are not created equal

#3 How have you proved that your chip is running at xxMHz?

#4 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand." - Heater's ex-boss

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El Tangas wrote:
... Mega328PB.
or mega324PB as mega328PB is on some third party boards whereas can't recall any mega324PB third party boards.

0-series megaAVR is the follow-on to PB megaAVR.

 

"Dare to be naïve." - Buckminster Fuller

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SMPS from Recom, are those those 3pin 78xx replacements?

Less soldering than a discrete solution, but trivial.

 

A shunt resistor together with a 2pin 0.1" header to measure the voltage over the shunt can be handy.

This 2 pin header can then also be jumpered if no current measurement is needed.

 

I like to have an obvious way to connect measurement equipment to GND.

2 holes of around 2mm diameter and 15 mm apart let you easily add a piece of copper installation wire (2.5qmm) for a big loop to connect the GND leads of your oscilloscope.

 

Layout for an UEXT connector may be handy.

It is a 10 pin IDC with UART, I2C, SPI & Power, specified by Olimex.

 

I also keep my development boards small, and then use a board to board connector (or IDC cable) to connect it to a regular protoboard.

Easy access to the unregulated supply will make it easy to add a 2nd voltage regulator for a different voltage.

 

Also: after a bit of practice soldering (the larger) SMD parts is easier than soldering through hole parts.

- No constant turning of the PCB

- Not getting confused by mirror images anymore.

- No components falling off.

- No clipping of leads for resistors, capacitors etc.

 

Also: I see you use tubes to isolate your wires.

I tend to use lacquered copper wire, with a hot (temperatur controlled) Iron ( 400 to 430 Celcius).

This is hot enough to burn through the lacquered wire, with no need for stripping the wires or cutting tubes.

(Download or open the picture in a separate tab to view it in higher resolution)

 

 

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

Last Edited: Wed. Aug 15, 2018 - 06:36 PM
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Paulvdh wrote:
Also: after a bit of practice soldering (the larger) SMD parts is easier than soldering through hole parts.
Is PCBA fab less expensive for SMD than TH?

Reasons :

  • advertisements from several PCBA fabricators for prototypes and very low rate production
  • Brian wants a pile for himself and to sell wink

Paulvdh wrote:
I tend to use lacquered copper wire, with a hot (temperatur controlled) Iron ( 400 to 430 Celcius).
Another instance except it's SMD :

ELM - Wiring Techniques

Extreme Wiring on the Prototyping Board

July 14, 1997

Update: December 16, 2014

http://elm-chan.org/docs/wire/wiring_e.html

 

"Dare to be naïve." - Buckminster Fuller

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I recently surprised myself and decided I really need a board with a ZIF socket.  And again when I figured out just how much extra room that would take :-(

 

I'm not sure that a barrel jack and regulator is so important any more, what with the ubiquity of 5V "USB" supplies.  I've got at least one design with two USB connectors - one for power only, and the other for actual USB Comm...

 

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I put an 8-pin header socket {such as comes on the Arduino UNO} on the pins of the Arduino Nano as shown:

Now, an 8-pin header strip on the daughterboard has Vcc, gnd, reset, I2C, and a few I/O pins that plug directly into the microcontroller board.

 

I have also taken to use an Arduino UNO with a TFT parallel shield (like an ILI9341) in a manner that makes a little A-Frame stand.  The pins for the entire right side of the TFT (D0-D7_D8-D13) shield are soldered to the Via pads of the UNO on that side.  Then I carefully bend the two boards to be at a 90 degree angle, so that the unsoldered edges of the TFT and the UNO are flush on the table surface. This makes a 45-degree stand to the user and the UNO board is its back support.  All peripheral boards, batteries, and connectors go into the  empty "V" space in the middle between the TFT and UNO boards.  I do have to do rework with 8-inch [20cm] pieces of thin wire-wrap AWG30 to connect the A0-A5 pins between the TFT and UNO.  Be sure to buy AWG30 wire wrap in an package that has an assortment of colors so that you can use the same color scheme between boards.  I suggest  red:Vcc  black(grey):gnd  blue:SCL  green:SDA  purple:SCK  yellow:MISO  orange:MOSI  white:reset.

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Simonetta wrote:

 

 

This makes a 45-degree stand to the user and the UNO board is its back support.  All peripheral boards, batteries, and connectors go into the  empty "V" space in the middle between the TFT and UNO boards.

Photo?

 

Ross McKenzie ValuSoft Melbourne Australia

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It hurts to see this   http://elm-chan.org/docs/wire/rc/wcs.jpeg

 

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Paulvdh wrote:
Layout for an UEXT connector may be handy.

It is a 10 pin IDC with UART, I2C, SPI & Power, specified by Olimex.

Here: https://www.olimex.com/Products/Modules/UEXT/

 

Or there's the XPlained Pro standard.

 

Or any number of other "standards" - proposed by every other board maker.

 

Also: I see you use tubes to isolate your wires.

we call it, "sleeving".

 

 

I like to have an obvious way to connect measurement equipment to GND.

very important!

 

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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I've seen some video of the elm-can (like) soldering.

Soldered with a big shaky iron, and often other wires are touched while soldering a wire next to it, which leads to that wire disconnecting and a lot of extra work.

 

It is made more like an piece of art, then as something practical.

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

Bunch of old projects with AVR's: http://www.hoevendesign.com

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Back from holiday and time to get a pile of doodles down on the screen.

 

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