Path: ...!weretis.net!feeder6.news.weretis.net!usenet.blueworldhosting.com!diablo1.usenet.blueworldhosting.com!nnrp.usenet.blueworldhosting.com!.POSTED!not-for-mail
From: Richard Smith <null@void.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Arduino + MCP9600 + thermocouple help needed
Date: Wed, 20 Mar 2024 16:30:43 +0000
Organization: BWH Usenet Archive (https://usenet.blueworldhosting.com)
Message-ID: <m1h6h0987g.fsf@void.com>
References: <m1v85j8ast.fsf@void.com> <utai8d$e7ee$1@dont-email.me>
	<utanb3$f5i9$1@dont-email.me> <m1ttl3qahq.fsf@void.com>
	<utb2r3$l04f$1@dont-email.me> <m134smjy0e.fsf@void.com>
	<ute49n$1ci6f$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain
Injection-Info: nnrp.usenet.blueworldhosting.com;
	logging-data="37907"; mail-complaints-to="usenet@blueworldhosting.com"
User-Agent: Gnus/5.13 (Gnus v5.13)
Cancel-Lock: sha1:5o4oMjqjbvEL1WI+6b68jjUtwbo=
	sha1:lXDwgJzqd2OfjojbjcDvyN8bVzQ= sha256:LRtfxf9GlCW2J0YyPixyQnWqhRD96CJUj642+pmz2cM=
	sha1:rL/EEqBxNdVvHOM51wLI8Yc6jU8= sha256:E7wIpoEXGvH+bqKbQaRwp3ZdvPVadUB+wR++9D0y3+w=
Bytes: 8443
Lines: 131

no@no.no (James Waldby) writes:

> Richard Smith <null@void.com> wrote:
>> "Jim Wilkins" <muratlanne@gmail.com> writes:
>>> "Richard Smith"  wrote in message news:m1ttl3qahq.fsf@void.com...
>>>
>>>> "Second picture is where commented-out "pinMode(2,
>>>> INPUT_PULLUP);". Initially LED lighting randomly when button not
>>>> pressed. Then added in the circuit the "pull-up" resistor connected to
>>>> on-board supply voltage and the circuit behaved like the first
>>>> circuit."
>
> The webpage pictures and your problem descriptions aren't clear enough
> or specific enough for definitive help.  Explicit wiring diagrams and
> complete code listings are needed, as well as context like Arduino
> IDE version number.  <https://arduino.stackexchange.com> may be of
> help if you can fully explain what you wired up and give a
> minimum-working-example for the problem,
>
> I suggest that when getting started, you first navigate to the Blink
> sketch (run Arduino, then File / Examples / Basics / Blink) and
> compile it and download it.  Then, to verify you are able to make and
> install program changes, copy it to a directory of your own with a new
> name, eg Blink2, and try a few simple changes, like substituting 13 in
> place of LED_BUILTIN, or 400 in place of 1000, etc. and download
> again.  If you want to try an external LED, connect it to some other
> IO pin (not D13) with eg a 2K resistor, put that IO number into your
> Blink2, test it, etc.
>
> Then, if you are working with a program like DigitalInputPullup,
> connect a switch between an IO pin and Gnd, say D2 and ground, per
> .png-image schematics in examples/02.Digital/DigitalInputPullup .
> When you download the program to the Uno and it starts running,
> setup() will be called, which will set up serial IO and pinModes for
> D2 and D13.  The pinMode(2, INPUT_PULLUP) statement places D2 into
> input mode with a pullup resistor to V+ (say 5V).  That is, if D2 is
> in the INPUT_PULLUP state, an internal resistor like 35K ohms (RPU min
> 20K, max 50K per spec sheet) is connected between V+ and D2, which
> means that if you leave D2 open, D2 will sit at V+; or if you connect
> D2 to ground, after transients settle (~1us) D2 will sit at 0V, and
> some number of uA, eg 5/35000 A ~ 143 uA, will flow through the pullup
> resistor.  You can measure that current by hooking an ammeter between
> the pin and ground if you want to calculate pullup resistance.  If the
> current's really high or is zero the pin's not in INPUT_PULLUP mode.
> If you have an external pullup and turn on INPUT_PULLUP, the effective
> pullup resistance is the two resistors in parallel.  If your external
> resistor is a pulldown (connected to Gnd instead of V+) the open-pin
> voltage [open aside from pull resistors] will be that of a resistor
> divider, instead of 0 or V+.
>
> Re the I2C problem with your MCP9600 breakout board - Again, wiring
> diagrams and code listings are needed for diagnosis.  One comment: You
> could write an if statement to try both addresses, 0x66 and 0x67,
> mentioned in the Pimoroni page, or a loop to try the whole range
> 0x60-0x67, proceeding ahead when a ready-test succeeds.  Or, for
> simpler programming you could make a program with one address,
> download and test it, then change it for each possible address until
> successful.  The I2C fails I've seen were due to wrong addresses,
> miswiring, bad chips, or in one case wires longer than a few feet.
>
>>> Unconnected inputs are sensitive antennas that pick up secret messages
>>> from space, or noise from fluorescent lights and radio/TV
>>> transmitters. Some even float to a middle level where they partly turn
>>> on both the input high and input low circuits, causing oscillation or
>>> higher power consumption. They are all best made high or low if not
>>> used. [...]
>
> Setting an open IO to low or high output like that is one approach,
> but on the Arduino Uno a simpler / less risky approach is to set
> pinMode to INPUT_PULLUP.  Note, ATmega328P microcontroller chip
> hardware as on an Uno sets all IO pins to INPUT during Reset, but boot
> firmware changes the modes of some pins like D0, D1, D13 as per eg
> <https://forum.arduino.cc/t/behavior-of-pins-during-reset-state/640285/12>
>
>> It is a bit of a thought that I would need an oscilloscope to
>> proceed much further.
>
> One can do a lot with indicator LEDs attached to several outputs.  You
> can connect a resistor in series with an LED between an IO pin and
> ground or 5V.  Eg, a 3.5V LED with a 1.5K resistor will draw 1 mA,
> either when the pin is low if series is between 5V and pin, or when
> the pin is high if series is between Gnd and pin. ( 0.001 A =
> (5V-3.5V)/1500 ohms.)  Or, because modern LEDs light up ok (visible
> but not annoyingly bright) with a few microamps, you can connect an
> LED between an IO pin and Gnd; turn it on with perhaps 43 uA, ie
> (5V-3.5V)/35000 ohms, when you set pinMode to INPUT_PULLUP; turn it
> off by setting pinMode to INPUT.  Note, outputting debug data via the
> serial port also is easy to do with Arduino.
>
> If you are uncertain how much electronics work you'll do, or have to
> really economize, an item like <https://www.amazon.com/dp/B0C6XPVLPZ>
> ($37) would get you at least basic scope function, making it possible
> to see switch bounce, PWM sequences, and other low frequency stuff.
> For a hundred or two more, you can get a 50MHz 2 channel scope like
> previously mentioned, a big step up.  If you're into micros for the
> long term, go ahead and get a medium cost 4 channel 100MHz or 200MHz
> scope, somewhere between $300 and $800.  Scopes in that range often
> have an input to accept data from optional add-on logic analyzer
> modules, adding 8 or more 0-1 inputs, and often have builtin protocol
> analyzers.  Eg, besides displaying an I2C waveform they show its data
> content as text on the screen.
>
>> I have seen videos of them used to diagnose even what is happening
>> when you push a push-button - all sorts of noise!  With the
>> oscilloscope showing very clearly.
>
> It's mostly switch bounce, not noise.  On some switches bounce will be
> over within just a few milliseconds (ms), on others it can be dozens
> of ms.  With search terms = arduino debounce, you can find code
> examples plus simple switch or switch+resistor circuits, and may also
> see pages like below with more-complex Schmitt trigger hardware
> debounce, or with low-pass filters, which in some cases are truely
> awful, amazingly bad.  Following link explains bounce problem and
> shows hardware and software debouncing with detailed code notes.
> <https://www.circuitbasics.com/how-to-use-switch-debouncing-on-the-arduino/>

Hi James, everyone

Thanks for the ideas in your reply.

Do thing of copying the example code then adding features.
eg. "blink" -> flashes-out morse code with LED on "breadboard"
At least got that far.

Addresses hint re. Arduino I2C to breakout board great.

Maybe accept crawl before tray to walk - do simpler code just to see if
can get the I2C connection going - forget trying to read the
thermocouple yet?
Thinking of the idea of trying the addresses.

Rich S