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Topic: MAX7219 problem (Read 1 time) previous topic - next topic

adwsystems

#60
Apr 24, 2019, 01:55 am Last Edit: Apr 24, 2019, 02:07 am by adwsystems
Quote
You can only use one of the three following connections:
1. Barrel Jack (for 7-12V power supplies)
2. Vin (for 7-12V power supplies)
3. 5V (for 5V power supply)
PICK ONE and ONLY ONE.
I really wish you would not confuse the poor fellow with such unhelpful nonsense!  :smiley-eek:
What are you talking about, Paul ? ? ? ? ? ? ? ? ?

What about this is do you not find correct?

Are you saying it is possible to supply power to more than one of these pins at once?

Is the barrel jack and Vin pin not for the input of 7-12V power?

Is the 5V pin not the input for a 5V power source?

If you put power into the first two, 5V will be present on the 5V pin but not with any capacity to do anything. So how is it not correct that only one of the three pins can be used at once?

You have not indicated what you feel is misleading about
Quote
5V: This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
Besides the lack of a caveat to indicate the 5V available is not able to power anything of consequence.

Paul__B

Besides the lack of a caveat to indicate the 5V available is not able to power anything of consequence.
Yes, you finally "got it".  That was exactly my complaint.  :smiley-lol:

The fellow appears to be having trouble comprehending that single detail.  Under the circumstances, and in particular that he is wishing to power something "of consequence", I feel that we need to be consistent in advice and not favour recidivism in any form.

Totally forget the "barrel jack" and "Vin" - never even mention them as possible options.

Even if you feel that they might be usable when someone has a UNO (or my preference: Nano) and nothing else beyond a few indicator LEDs and resistors, I think the requirement for a 5 V power supply - and I cannot say this too often; "phone chargers" are by far the most readily available option - should be emphasised as the preliminary basis of any further progress.

adwsystems

#62
Apr 24, 2019, 12:10 pm Last Edit: Apr 24, 2019, 12:17 pm by adwsystems
Yes, you finally "got it".  That was exactly my complaint.  :smiley-lol:

The fellow appears to be having trouble comprehending that single detail.  Under the circumstances, and in particular that he is wishing to power something "of consequence", I feel that we need to be consistent in advice and not favour recidivism in any form.
Please reread and dwell on my statement.
Quote
You can only use one of the three following connections:
1. Barrel Jack (for 7-12V power supplies)
2. Vin (for 7-12V power supplies)
3. 5V (for 5V power supply)
PICK ONE and ONLY ONE.
We are talking apples and oranges. I am talking power in. You are talking power out. Your complaint has nothing to do with what I am saying. I am saying to choose one of the three power inputs and you are "confusing" issues by including power output (ie., using power from the 5V pin). I never said to use the 5V power out.

The instructions above are simple and perfectly clear. Choose one of the three and forget the other two exist. No matter what design choice is made, it is not possible to follow the instructions and to use 5V as a power output. To do so means either there is not power applied to the barrel jack or Vin (use only one and you selected 5V to be used as an output) or you have connections to two of the three. Either way you are not following the instructions.

The 5V pin as a power source (out) is useless. On that we agree.

Totally forget the "barrel jack" and "Vin" - never even mention them as possible options.

Even if you feel that they might be usable when someone has a UNO (or my preference: Nano) and nothing else beyond a few indicator LEDs and resistors, I think the requirement for a 5 V power supply - and I cannot say this too often; "phone chargers" are by far the most readily available option - should be emphasised as the preliminary basis of any further progress.
Well, we will have to agree to disagree on this point. The ability to have a flexible voltage input is quite useful.

My complaint is the fact they recommend 9V and built the regulator limit to 12V. I don't like running things (electronics) at there design limit. Who does? Furthermore, what the #!@$ heck runs on 9V? How many devices out there run on 9V? There are tens of magnitudes (10-1000000x) more devices available that run on 12V then on 9V.

Paul__B

We are talking apples and oranges. I am talking power in. You are talking power out. Your complaint has nothing to do with what I am saying. I am saying to choose one of the three power inputs and you are "confusing" issues by including power output (ie., using power from the 5V pin). I never said to use the 5V power out.
...
The 5V pin as a power source (out) is useless. On that we agree.
Yes, of course I am talking about "power out" if that is the thing that is required to complete a project as in this particular case.  If you need 5 V for a purpose and the Arduino cannot be used as a source of 5 V, then a power source that will not provide that 5 V is simply not relevant; not an option.

Your stance is very peculiar, since you appear to keep criticising the use of two separate power supplies, but powering the Arduino via the regulator at 9 V mandates a second supply for the 5 V yet you are suggesting that it is "possible" to use a 9 V input.

How many devices out there run on 9V?
In my experience, most cordless phones, older telephone modems (when these were a meaningful device) and ADSL boxes, network devices, Ethernet hubs, toys, radios and many others.

These are the things that were contemporaneous with the original Arduinos, so Arduino made use of the available power packs.

adwsystems

#64
Apr 24, 2019, 07:24 pm Last Edit: Apr 24, 2019, 07:42 pm by adwsystems
Your stance is very peculiar, since you appear to keep criticizing the use of two separate power supplies, but powering the Arduino via the regulator at 9 V mandates a second supply for the 5 V yet you are suggesting that it is "possible" to use a 9 V input.
Where and what are you talking about? ? ? ? When ever did I mention using multiple power supplies? I don't care how many power supplies you have so long as you follow the instruction. Please tell me how you can connect multiple power supplies to the Arduino and still follow the instruction.

Here is the instruction for your reference
Quote
You can only use one of the three following connections:
1. Barrel Jack (for 7-12V power supplies)
2. Vin (for 7-12V power supplies)
3. 5V (for 5V power supply)
PICK ONE and ONLY ONE.
I don't care how you use the pins so long as you follow the instructions. If you choose to use the barrel jack, you cannot use the 5V pin as power source as that will violate the instruction. If use use the 5V pin as a power source and follow the rule then the board has no power. So the instruction inherently prevents the 5V pin from being used as a power source.

You will have to explain very clearly how this contradicts anything you have said or any good (Arduino) design practices.

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