programming Arduino Nano

[Robert Atkinson 2Participant @robertatkinson2]

One obvious issue with SOD’s diagram is no power supply for the Arduino and display. They can’t run directly off a 24V supply.

 

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

One obvious issue with SOD’s diagram is no power supply for the Arduino and display. They can’t run directly off a 24V supply.

 

Not an obvious issue to me!  The purpose of the diagram was only to confirm which indexer Ted has. This isn’t a new build – it’s a repair where, maybe, the Uno has failed.  How the Arduino is powered is a mere detail so far as I’m concerned.

For those who do care, MEW 249 has this circuit diagram.  The Uno is powered from the 12Vdc 5A regulated supply used by the motor:

The electrical load on the Arduino is low.  The TB6960 is miniscule – it has high impedance inputs.   The LCD Display is greedier – 3mA with the backlight OFF,  20mA with the backlight ON.  20mA isn’t a problem for an Arduino Uno.  Carl Wilson’s design isn’t mad because 12v is the maximum recommended external supply to a Uno, and the regulator only has to dissipate about 0.3W.

No point, I suggest, in picking at a design published December 2016 that worked until recently!

My plan is to send Ted a tested Uno loaded with Gary Liming’s code.   I’m slightly worried that Ted doesn’t have a MEW249/Liming’s indexer.  Alternatives include this.    Or this.  Or even the one I wrote before finding others had got there first.  Gary’s 5 button design requires nested menus which aren’t everyone’s cup of tea, a problem eliminated by a 4×4 keypad.  (16 buttons!)

Dave

[John HaineParticipant @johnhaine32865]

It may have recently failed because the linear regulator decided it had spent enough time too hot..

[duncan webster 1Participant @duncanwebster1]

Recommended input volts to UNO is 7-12V, max drain from total pins = 40mA. If I were drawing 20mA to power a display backlight I’d use a 7805 to provide the 5V, not the internal regulator. Why? I’ve had a problem in the past with Arduino regulators, admittedly on pro minis, and a 7805 doesn’t cost much. This could be tested by using a wall wart to supply some 5V (phone charger or similar) and applying it to the 5v pin

[SillyOldDufferModerator @sillyoldduffer]

Always good to finish the story!   Delay mainly due to xmas and me being poorly.

Ted suspected that his divider’s Uno had failed, so I sent him a replacement loaded with Gary Liming’s divider program.  Ted sent me a new Uno and the suspected broken one, which I bench tested.  It started and crashed, proving Ted’s diagnosis was correct, and we were on the right track.  Hurrah!

Apart from crashing the broken Uno was OK.  It uploaded programs from the IDE correctly and all the pins work.  Corrupt program confirmed.  Don’t know what mangled it: power spike maybe.

Anyway, Ted’s divider works again and I’ve gained a working Uno.  We’re both happy!

🙂

Dave

 

[Michael GilliganParticipant @michaelgilligan61133]

Well done, Dave !

… some Good Karma is what we need in the world.

MichaelG.

[Author]

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