[TriEmbed] Raspberry Pi GPIO

[Rodney Radford]

Why are you trying to cut power to the chip instead of just disabling the
outputs?

I thought the intent was to keep the chip from getting hot, which it should
only do when powering the output lines.

It is normally not wise to turn off power to chips and still drive the
inputs to those chips - it is an unexpected operational mode and could
damage the chip

On Mon, Mar 30, 2015 at 2:52 PM, Grawburg <grawburg at myglnc.com> wrote:

> The Enable did  disable/enable the chip which was demonstrated by setting
> the Pi GPIO HIGH and the LOW. But, I wanted to actually disable the power
> to the chip without disconnecting the power source by using a transistor
> (which I've used for more basic projects like powering a piezo buzzer with
> an external source).
>
> I wish I could recreate what I was doing and see what slip I made...but
> I'm not going to risk it :-)
>
> Brian
>
>
> ------------------------------
> -----Original Message-----
> From: "Rodney Radford" <ncgadgetry at gmail.com>
> To: "Grawburg" <grawburg at myglnc.com>
> Cc: "Triangle Embedded Devices" <TriEmbed at triembed.org>
> Date: 03/30/15 02:23 PM
> Subject: Re: [TriEmbed] Raspberry Pi GPIO
>
> Never is a very long time. Regardless of what you are doing, it is always
> possible for a small wiring error to wipe out a Raspberry Pi, Arduino, or
> any other computer if wired incorrectly.
>
> So far I have only wiped out one Raspberry Pi and in that case all I was
> doing was wiring up some servo motors - I still don't know what i did wrong
> as when I saw the magic smoke, I quickly started pulling out wires. I
> checked my schematic, all looked good, and then wired a new Raspberry Pi up
> the same way (the other one was toast) and it worked without a problem. I
> can only assume I made a simple connection error.
>
> As to what you are trying to do, could you elaborate and provide a few
> more details about what you were trying to wire up?
>
> If you were trying to control the Enable line of the A4988, it is an input
> only connection to the A4988, so it should be treated the same way you do
> the other inputs to that chip.
>
>
>
> On Mon, Mar 30, 2015 at 2:06 PM, Grawburg <grawburg at myglnc.com> wrote:
>
>> I will never attach anything that even looks or smells like it could send
>> current back to the RPi by connecting directly to the GPIO. I just crapped
>> out a Pi while working with a stepper motor, and I'm not really sure how. I
>> was trying to set up a transistor to switch the power on/off to the control
>> board (the Enable option still allows current to the motor) and something
>> happened that fried the Pi.
>>
>> If I can't fully isolate the Pi with a logic level shifter or I/O port
>> expander I don't think I'll try to hook up a project. And I'm sure not
>> going to use a transistor without a shifter.
>>
>>
>> Brian Grawburg
>>
>>
>>
>>
>>
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>
>
>
>
>
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