Tag: Allwinner H2+

Control the orange pi zero GPIO

After installing my orange pi zero. I tried to use my board the reencode some video file that use xvid/ac3 to x264/aac with the ffmpeg linux command.

The problem was that it took more than two hours at 100% cpu usage on the 4 cores to reencode the video, during that time the cpu was getting instantly too hot and, as a result, was heavily throttling . I tried to use a radiator, and it significantly reduced the amount of throttling but it was not eliminating it, since eventually the cpu reached pretty high temperature.

I decided to add a fan to blow on the radiator to reduce even further the cpu temperature.

I didn’t want the fan to be running all the time so I decided to use the gpio function of my board to control the state of a pin to start and stop a fan.

The problem is that the logic levels sent by the gpio is 3.3v which is much to low to start the fan i own.

My fan is a 12v fan, but it turns out that it can run at 5v, it just have a lot of trouble starting, most of the time when I put 5 v on the fan, I just see a very small movement, and then nothing, I just have to give a little push, and then it will start

Of course, this is not going to be OK. I must find a way to start that fan without that initial push.

To send 5v instead of 3.3v to the fan I used a PNP transistor that will be controlled by the 3.3v signal.

On this photo , the GPIO control pin is wired to PIN number 23 , after i took that picture i changed it to pin number 7

 

As you can see on the photo, the pin one of the PNP transistor is wired to a GPIO pin, the pin 2 is wired to the pin 2 of the board which provide constant 5v,and then the pin 3 is wired to the the red wire of the fan.
The black fan wire is connected to the pin number 6 of the board.

Here is a little schematic of the wiring.

To control the gpio I used wiringpi program that I found at this URL

At first I tried to use the gpio pin number 23 but, for some reason I failed to change the state of that pin using the wiring pi library.

I then chosed to use the pin number 7 which is named GPIO.7 in the “gpio readall” command.

First I configured the pin 7 as an output using that command

gpio mode 7 out

Then i use that command to set pin 7 at logic level 1 (3.3v)

gpio write 7 1

But even with all that, my fan still needed a little push to start turning.

After a good afternoon where I considered buying a cheap and small 5v fan on one of the classic Chinese website, i remarked that if my control GPIO pin was not soldered and I disconnected and reconnected very rapidly the control wire, the fan was starting every time.

The idea of a bash script exploiting this fact was born.

Here is the script that works for me every time!

#!/bin/bash

gpio mode 7 out
i=0
while (($i < 10))
do
gpio write 7 1
sleep .1
gpio write 7 0
sleep .05
i=$(($i+1))
echo $i
done

gpio write 7 1

This  script put the pin 7 in output mode, then switch the state of pin 7 rapidly provoking the startup of the fan.  At the end of the script the pin 7 is left in the 1 state.

To be sure the fan started, I usually launch this script 3 times, but it’s overkill and one time is enough most of the time.

When I want to stop the fan, I just launch the command

gpio write 7 0

And the fan stop immediately,

Now creating a script that launch automatically the fan when the cpu get above a predefined temperature is going to be extremely easy, I will describe it in another article.

Even if the fan is turning very very slowly , it does have a very significant effect on cpu temperature

Reduction of more than 10 degrees

Orange PI Zero : Control the onboard leds

 

The Orange PI zero is equipped with two onboard leds ,

 

One red , and one green ,
armbian give you the ability to control very easily the state of theses leds.

to turn on the red led you can use this command : echo 1 > /sys/class/leds/red_led/brightness
to turn off the red led you can simply launch : echo 0 > /sys/class/leds/red_led/brightness

to turn on the green led you can use this command : echo 1 > /sys/class/leds/green_led/brightness
to turn off the green led you can simply launch : echo 0 > /sys/class/leds/green_led/brightness

You can put some sleep command between the on and off, and use this functionality to notify you for example that a cron script is running.

Orange Pi Zero : How to get the CPU temperature

If you purchased the small yet awesome orange pi zero on Aliexpress you certainly had huge problems to download some OS images on the official Orange PI website ,

you can download an image on the armbian website that’s compatible with the Orange pi zero

when your orange pi zero is finally fonctional there is several way to get the current temperature of the CPU.

first you can use the command : armbianmonitor -m this command is going to give you , the uptime , cpu speed and the current CPU temperature every 6 seconds.

 

but if you want to get that temperature for graphing purpose for cacti , munin , or grafana this command is not going to be usefull because of the autorefresh functionality

there is an other command that just return the cpu temperature

cat /sys/devices/virtual/thermal/thermal_zone1/temp 

OR

cat /sys/devices/virtual/thermal/thermal_zone0/temp

there is two sensor inside the Allwinner H2+ , you can add the two values and then divide the result by two to get an average temperature.

then you can graph the temperature using grafana for example