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GPIO high at board start, want to disable


jgauthier
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Hello,

 

  I have a GPIO pin that is high when starting the board.  I am trying to force it low.  

Taking a look at gpio readall

 

 +-----+-----+---------+------+---+---Pi ?---+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
 |  12 |   8 |   SDA.1 | ALT5 | 0 |  3 || 4  |   |      | 5v      |     |     |
 |  11 |   9 |   SCL.1 | ALT5 | 0 |  5 || 6  |   |      | 0v      |     |     |
 |   6 |   7 | GPIO. 7 | ALT3 | 0 |  7 || 8  | 0 | ALT3 | TxD     | 15  | 13  |
 |     |     |      0v |      |   |  9 || 10 | 0 | ALT3 | RxD     | 16  | 14  |
 |   1 |   0 | GPIO. 0 | ALT3 | 0 | 11 || 12 | 0 | ALT3 | GPIO. 1 | 1   | 16  |
 |   0 |   2 | GPIO. 2 | ALT3 | 0 | 13 || 14 |   |      | 0v      |     |     |
 |   3 |   3 | GPIO. 3 | ALT3 | 0 | 15 || 16 | 0 | ALT3 | GPIO. 4 | 4   | 15  |
 |     |     |    3.3v |      |   | 17 || 18 | 0 | ALT3 | GPIO. 5 | 5   | 68  |
 |  64 |  12 |    MOSI | ALT3 | 0 | 19 || 20 |   |      | 0v      |     |     |
 |  65 |  13 |    MISO | ALT3 | 0 | 21 || 22 | 0 | ALT3 | GPIO. 6 | 6   | 2   |
 |  66 |  14 |    SCLK | ALT3 | 0 | 23 || 24 | 0 | ALT3 | CE0     | 10  | 67  |
 |     |     |      0v |      |   | 25 || 26 | 0 | ALT3 | CE1     | 11  | 71  |
 |  19 |  30 |   SDA.0 | ALT3 | 0 | 27 || 28 | 0 | ALT3 | SCL.0   | 31  | 18  |
 |   7 |  21 | GPIO.21 |  OUT | 1 | 29 || 30 |   |      | 0v      |     |     |
 |   8 |  22 | GPIO.22 | ALT3 | 0 | 31 || 32 | 0 | ALT3 | GPIO.26 | 26  | 354 |
 |   9 |  23 | GPIO.23 | ALT3 | 0 | 33 || 34 |   |      | 0v      |     |     |
 |  10 |  24 | GPIO.24 | ALT3 | 0 | 35 || 36 | 0 | ALT3 | GPIO.27 | 27  | 356 |
 |  17 |  25 | GPIO.25 | ALT3 | 0 | 37 || 38 | 0 | ALT3 | GPIO.28 | 28  | 21  |
 |     |     |      0v |      |   | 39 || 40 | 0 | ALT3 | GPIO.29 | 29  | 20  |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+---Pi ?---+---+------+---------+-----+-----+


it can be seen the following line is active:

+-----+-----+---------+------+---+---Pi ?---+---+------+---------+-----+-----+
| BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
+-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
|   7 |  21 | GPIO.21 |  OUT | 1 | 29 || 30 |   |      | 0v      |     |     |


I've tried to force it off, but doesn't seem to work:

 

/dts-v1/;
/plugin/;

/ {
        compatible = "allwinner,sun8i-h3";

        fragment@0 {

                target = <&pio>;
                __overlay__ {
                        poweroff_pins:poweroff_pins {
                        allwinner,pins = "PA7";
                        allwinner,function = "gpio_out";

                        };
                };
        };

        fragment@1 {

                target-path = "/";
                __overlay__ {
                        poweroff: poweroff {
                        compatible = "gpio-poweroff";
                        gpios = <&pio 0 7 1>;
                        };
                };
        };
};


Is this the wrong approach? 

Thanks!

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18 hours ago, jgauthier said:

Is this the wrong approach?

What kind of board are you using ?

Your "gpio" tool seems to have been compiled for the wrong board, because PA7 should be named GPIO7 not GPIO21 ...

Try using gpio sysfs :

echo 7 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio7/direction 
echo 0 > /sys/class/gpio/gpio7/value 

 

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@martinayotte Well,  I think it's more complicated than that.  I'm using the WiringPI from here for the BPI series here:

https://github.com/BPI-SINOVOIP/BPI-WiringPi2/tree/master/wiringPi

 

in wiringPi/wiringPi_bpi.c it looks for /var/lib/bananapi/board.sh

In there I have this entry:

BOARD=bpi-m2z

 

That said,  sysfs doesn't work.  

echo 7 > /sys/class/gpio/export
-bash: echo: write error: Device or resource busy

 

I can access the GPIO pins with the gpio utility using the physical pin:

gpio toggle 21

 

I don't believe (but I also don't know) that the DTS uses the wiringpi interface. It seems much lower level than that.  So, I would think in the DTS file I can access it by gpio 7, which is the BCM ID. PA7, specifically.

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Here's what I got:

gpiochip0: GPIOs 0-223, parent: platform/1c20800.pinctrl, 1c20800.pinctrl:
 gpio-1   (                    |sysfs               ) in  hi IRQ
 gpio-7   (                    |vcc-af-csi          ) out lo
 gpio-110 (                    |vdd-1v5-csi         ) out hi
 gpio-203 (                    |host-wakeup         ) in  lo
 gpio-204 (                    |shutdown            ) out hi
 gpio-205 (                    |device-wakeup       ) out higpiochip1: GPIOs 352-383, parent: platform/1f02c00.pinctrl, 1f02c00.pinctrl:
 gpio-353 (                    |vdd-cpux            ) out lo
 gpio-355 (                    |power               ) in  hi IRQ ACTIVE LOW
 gpio-358 (                    |usb0_id_det         ) in  hi IRQ
 gpio-359 (                    |reset               ) out hi ACTIVE LOW
 gpio-362 (                    |bananapi-m2-zero:red) out lo

 

Thanks, I hope this means more to you than it does to me ;)

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34 minutes ago, jgauthier said:

gpio-7   (                    |vcc-af-csi          ) out lo

That is why you're getting "Device or resource busy" ...

 

Are you sure we are talking about an Armbian build here ? Because "vcc-af-csi" means this pin is related to a CSI camera...

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Yes, it's an armbian build,  I built it myself.  I've built a DTS package to enable the CSI camera.  Unfortunately, I do not have access to that DTS configuration to look at it right now and confirm what pin it's using.   I'll have to look it up later and post it.  Thanks!

 

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@martinayotte You're correct.

reg_vcc_af_csi: vcc-af-csi {
    compatible = "regulator-fixed";
    regulator-name = "vcc-af-csi";
    regulator-min-microvolt = <2800000>;
    regulator-max-microvolt = <2800000>;
    gpio = <&pio 0 7 GPIO_ACTIVE_HIGH>; /* PA7 */
    enable-active-high;
    regulator-boot-on;
    regulator-always-on;
};


PA7 is assigned as HIGH, to the CSI connector.

My issue is that due to forgetting about this, I've pulled PA7 out for another custom use.  That was very bad.  PA7 will have to be reassigned for my custom use.

 

While this did not go where I thought, you helped me look at stuff and figure out my problem.  I set this CSI connector up months ago and completely forgot about it.

Thank you!

 

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