jpham
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Joined: Thu Sep 20, 2018 4:19 am

run / global_en ?

Thu Oct 04, 2018 3:19 am

I notice the Run/global_en in RSPI 3B but not in RSPI 3B+ board - is it possible to send a RESET low from host computer to the RSPI RUN port?
assuming I convert my /RESET from 5V to 3.3V and solder my system /reset line to Raspberry RUN line ?

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Imperf3kt
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Location: Australia

Re: run / global_en ?

Thu Oct 04, 2018 5:37 am

The Run header is for booting a Pi that is shut down but still powered. It works by shorting the pin to ground, not 3v3
Stop plugging your fan directly into the GPIO 5v
https://www.electronics-tutorials.ws/power/transient-suppression.html

hippy
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Re: run / global_en ?

Thu Oct 04, 2018 10:04 am

jpham wrote:
Thu Oct 04, 2018 3:19 am
I notice the Run/global_en in RSPI 3B but not in RSPI 3B+ board
Not sure how you mean; the Pi 3B+ has RUN plus GLOBAL_EN, the Pi 3B has RUN.

It would seem you could just use RUN as you previously would.

The RUN signal appears to be an active-high, pulled-high, open-collector configured signal on both, so you could probably just use a diode to interface to an external 5V/0V signal to pull it low as /RESET -

Code: Select all

                        -.- 3V3
                        .|.
                        |_| 10K
External     Diode       |
 signal   >---|<|---(o---^---<> RUN

jpham
Posts: 18
Joined: Thu Sep 20, 2018 4:19 am

Re: run / global_en ?

Fri Oct 05, 2018 2:01 am

ok, I'm confuse - two reply - shorting the pin to gnd - make the Pi wake up, the other - short to gnd -reset ?
can we get some clarification on how to do a system reset ? I look at the schematic - no system reset ?

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Imperf3kt
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Re: run / global_en ?

Fri Oct 05, 2018 2:36 am

The Run pin (well its not really a pin as it isn't populated) is directly connected to the Broadcom SOC according to the reduced schematics.
https://www.raspberrypi.org/documentati ... educed.pdf
Stop plugging your fan directly into the GPIO 5v
https://www.electronics-tutorials.ws/power/transient-suppression.html

klricks
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Re: run / global_en ?

Fri Oct 05, 2018 3:35 am

jpham wrote:
Thu Oct 04, 2018 3:19 am
I notice the Run/global_en in RSPI 3B but not in RSPI 3B+ board - is it possible to send a RESET low from host computer to the RSPI RUN port?
assuming I convert my /RESET from 5V to 3.3V and solder my system /reset line to Raspberry RUN line ?
All B models have the RUN feature.
For the 3B+ see schematic grid location C-4: https://www.raspberrypi.org/documentati ... educed.pdf

Pulling the RUN low will cause a hard reset.
If the OS is running then the CPU will be immediately halted... When RUN is released the RPi will reboot.
If the CPU is already shut down (halted) then pulsing the RUN will restart the RPi.

If the RPi is running then RUN should only be issued when the RPi has crashed or has become unresponsive.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Stretch w/ Desktop OS.

hippy
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Re: run / global_en ?

Fri Oct 05, 2018 8:33 am

jpham wrote:
Fri Oct 05, 2018 2:01 am
ok, I'm confuse - two reply - shorting the pin to gnd - make the Pi wake up, the other - short to gnd -reset ?
Connecting RUN to 0V when the Pi is running will stop it running and then hold it in its reset state.

Connecting RUN to 3V3 or not connecting to it at all will release the Pi from its reset state and start it running.

RUN is what would be /RESET on other systems. Most manufacturers choose to name the pin with its active low function; /RESET. Broadcom, for whatever reason, chose to name the pin with its active high function; RUN.

jpham
Posts: 18
Joined: Thu Sep 20, 2018 4:19 am

Re: run / global_en ?

Fri Oct 05, 2018 10:49 pm

thanks - I was confuse - usually the /reset means entire system reset (restart to a boot up state)

the big question now - if I have a switch on my board, does the customer has to solder a wire from RPI board to my board?
and why doesnt RSPI just put the "run" on a pin header? :-) - maybe they run out of pins ?

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