Button on the custom board

[backstreet.devisor]

Good Day!

I am trying to adapt the example from lesson number 4 (Data exchange in BLE, exercise 2) for use on my custom board.

The example uses the library "dk_buttons_and_leds". At the moment I don't understand how the program determines which button state should be sent via bluetooth to the smartphone. 

There is one button on my board (connected to pin 30) whose state I want to send to my smartphone. 

buttons {
		compatible = "gpio-keys";
		button0: button_0 {
			gpios = <&gpio0 30 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
			label = "Button 0";
		};
	};
	
	/* These aliases are provided for compatibility with samples */
	aliases {
	
		button0 = &button0;
	};

In the program code, the button is defined as:

#define USER_BUTTON DK_BTN1_MSK

I originally thought that DK_BTN1_MSK meant Button0 (DK_BTN2_MSK = Button1, DK_BTN3_MSK = Button2 ...) in the device tree, but as it turns out I was wrong. Because after changing button0 to button3 in the device tree -->

buttons {
		compatible = "gpio-keys";
		button3: button_3 {
			gpios = <&gpio0 30 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
			label = "Button 3";
		};
	};
	
	/* These aliases are provided for compatibility with samples */
	aliases {
		
		button3 = &button3;
	};

I didn't see any changes. The board still kept transmitting the value of my button to the phone. 

Please explain to me how to correctly define the button whose value I want to receive via bluetooth.

Thank you. 

[Hung Bui]

Hi,

Could you let us know which exact file did you modify the device tree to change the button ? 

Or did you create an overlay file ? 

Did you use the DK board to build your application or define your own board ? 

[backstreet.devisor]

Hi.

I created my own custom_board_nrf52840.dts file and made changes in it.

[Hung Bui]

Then you may want to check if the dts file has been actually used. 

One trick I usually do is to try make an error in the file and compile to see if I get build error or not. 

I did a quick test here and the attached board worked for me, I changed button 0 to pin 30 and can see that now the input on Pin 30 is sent to the phone in the peripheral_lbs sample. 

4186.boards.zip

[backstreet.devisor]

My .dts file is actually in use.
I don't understand how the program matches the #define string

#define USER_BUTTON DK_BTN1_MSK

with button number 3.

buttons {
		compatible = "gpio-keys";
		button3: button_3 {
			gpios = <&gpio0 30 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
			label = "Button 3";
		};
	};
	
	/* These aliases are provided for compatibility with samples */
	aliases {
		
		button3 = &button3;
	};

Changing the button number in the .dts file doesn't change anything. No matter what button number I write, I still get the value from pin 30, although DK_BTN1_MSK is written in #define.

[Hung Bui]

Hi again, 

Please explain why you want to configure button3 instead of button 0 ?
If you use DK_BTN1_MSK then you should modify button0 instead of button 3. 

If you want to use button 3 you should use DK_BTN4_MSK

[backstreet.devisor]

Initially I thought so too, that
DK_BTN1_MSK corresponds to button 0 on my board. But it doesn't matter what number I assign to button 0, 1, 2 or 3 in the .dts file. The data of the button specified in the .dts is still transmitted via bluetooth, although this should not happen if the button number is different from 0 when DK_BTN1_MSK is specified

So I'm trying to figure out why this is happening, but I can't do it.

[backstreet.devisor]

I only have one button on the board. There are no other buttons.

[Hung Bui]

Hi, 
Did you use my board files in boards.zip ? 
I used that and change 

#define USER_BUTTON             DK_BTN2_MSK 

Then I can see that the button to be detected is now button 2 (GPIO pin P0.12) instead of P0.30 as in DK_BTN1_MSK

Please try testing with the board files I provided and the peripheral_lbs.

[backstreet.devisor]

Hi.

I tested your .dts sample.
If I write #define USER_BUTTON DK_BTN2_MSK and change it to Button1 in the .dts file, the button state is not read.

Only #define USER_BUTTON DK_BTN1_MSK works, and it doesn't matter what number I assign to the button in the .dts file.
:(

[Hung Bui]

Something wrong with your dts file. 
So if you use my board file, and keep #define USER_BUTTON             DK_BTN1_MSK  (don't modify anything)
Do you see that pin P0.30 is sampled not P0.11  ? 

[backstreet.devisor]

Sorry for a stupid question, but how do I see which pin corresponds to DK_BTN1_MSK?
When I put the cursor over DK_BTN1_MSK I see BIT(DK_BTN1).