Have a look at PCB slide switches and push buttons, they will often plug into the board.

Mike

Try adding 'breadboard friendly' when searching ebay/amazon etc for parts.

I don't normally bother fixing stuff down when breadboarding but occassionally use a thin ali panel much like XD351 and his angle for switches and pots, and plasticene or insulating tape for temporarly holding displays in position. Some modelling clays are more suitable than others. It has to be a bit sticky without being too soft or messy.

Dave

Many folk have used the Nokia 5110 display in their projects or is that too small?

My current project uses a Sainsmart TFT Shield with a 3½ screen, which plugs into a Mega. (Although the link is to the US, I got mine in the UK, probably via Amazon.) Display and touch both work ok with the TFT library.

The main problem with TFT screens is the large number of connections needed. Lots of wires, and not many Input Output pins left for other work. I find a Mega provides much more room to maneuver than the Uno – more pins.

The shield considerably simplifies and tidies up the wiring! It also comes with an SD-Card interface, which may be handy.

Getting at the unused pins on the Mega under the shield is slightly awkward but right angled connectors fit OK. The main downside is the cost, but it's a neat solution.

Dave

I have been looking at the other direction – not wanting to work through lots of menus to put in data I thought of BCD switches. While the pcb mount ones are common anything larger is frighteningly expensive. So going with switches and binary input until I can make my own rotary BCD.

If you're OK programming then have a look at the nextion displays from Itead, they use a serial connection to the Arduino or Pi etc.

They have a PC design tool that allows you to create all the GUI and upload it to the display then control it using an Arduino, I found it quite easy to use when I got my head around it and there's quite a bit of information on the web.

**LINK**

Did you realise the attached interrupt only works on certain pins?

Two ways to count pulses:

• spin digitalRead() in a loop until a pulse is detected, then count it. Advantage is simplicity. Huge disadvantage is that nothing else can be done while the Arduino is waiting for the next pulse. As an approach it's only suitable for trivial processing.
• Set up an interrupt and call an ISR. This allows the arrival of a pulse at any time to suspend whatever the Arduino is doing, execute the ISR, and then resume from the break. Advantage is the microcontroller can appear to be doing several things at once. Disadvantage is interrupts are bit more complicated to understand, mainly because of the time element.

Two common problems:

• Any variable shared between an ISR and the rest of the world must be in scope of both functions and declared 'volatile'. Scope can be fixed by declaring shared variables at the top of the source code (before any functions) making them global. The 'volatile' keyword tells the compiler that it must not cache the declared variable to optimise performance. If a global is cached, it's entirely possible for it's value at point of use to be wrong because the ISR updated the master leaving other functions with out-of-date copies. Then the program doesn't work as expected.
• Because an ISR interrupts other functions that can themselves be time critical, the ISR should be short and quick. If an ISR is long-winded and the code it interrupted times-out, then chaos can ensue.

Both issues produce hard to diagnose bugs. You can have code that's logically correct and be getting random errors or a complete breakdown depending on the state of a buffer and/or how long something takes.  Very confusing.

Happy to look at your code Peter if that helps.

Dave

Edited By SillyOldDuffer on 10/10/2018 16:43:23

Yes you are right, but on a nano it compiles and works fine using int.0 and int.1.