Setting a specific pin to high status when the device powered
#7
(10-06-2016, 07:42 PM)pfeerick Wrote:
(10-06-2016, 04:15 AM)mbt28 Wrote: Hi,

I can use both 3.3v or 5V logic, I have no issue with it. It has to be high immediately when the board powered and It should go to zero when the shutdown sequence completed, then the external linbus IC will cut all the supply until it receives a data on the line.

Thanks.

Well, the question then will be whether the 0.3v that I measured when the pine64 was off (remembering that this was with nothing 'loading' the pin) is  low enough for your linbus to consider the pine64 off. It will come on and stay on (3.3v, RPi pin 1) when the the pine64 starts up, and goes off when the pine64 shuts down, so it meets those criteria.
 
Use a comparator on the PMIC output pin for DCDC1;  with an open collector, and pullup for 3v3 or 5v.

Set the threshold on the comparator for something reasonable so that the 'off' level ( .3 , whatever ) snaps the output to zero and holds it there. The LM339 is good in this kind of application.  These make great level detectors, operate at a wide voltage range, and have open collector outputs;  pullups are 'required'.
marcushh777    Cool

please join us for a chat @  irc.pine64.xyz:6667   or ssl  irc.pine64.xyz:6697

( I regret that I am not able to respond to personal messages;  let's meet on irc! )
  Reply


Messages In This Thread
RE: Setting a specific pin to high status when the device powered - by MarkHaysHarris777 - 10-06-2016, 09:01 PM

Possibly Related Threads…
Thread Author Replies Views Last Post
  Portable USB-Powered Monitor mribunal 4 5,061 02-03-2017, 05:28 AM
Last Post: stevenmeza07
  High speed I/O richw42 3 3,138 01-15-2017, 04:08 PM
Last Post: richw42
  Setting up UART2 for Adafruit GPS hat stephen fleming 1 1,771 05-13-2016, 03:20 PM
Last Post: peterz

Forum Jump:


Users browsing this thread: 1 Guest(s)