External input & output on nRF52840

RE: External input & output on nRF52840

Amanda Hsieh — Thu, 27 Aug 2020 13:01:34 GMT

Hi Alexa,

[quote user="alexa"]When I change the LEDS_ACTIVE_STATE to 1, the other LEDs remain on for the whole time, without me specifying that. (i.e I don't modify the rest of the code)[/quote]

How did you add your external LED in the pca10056.h? Could you insert the related part in the pca10056.h?

[quote user="alexa"]but I cannot find them. Could you please tell me in which .c or .h file should I look for them?[/quote]

You can take a look at the BSP Example on how to control the LED.

[quote user="alexa"]Could you plase tell me in which source files should I look for the mentioned functions?[/quote]

I think you are looking at the nRF5_SDK\examples\ble_peripheral\ble_app_blinky, but I mean nRF5_SDK\examples\peripheral\blinky.

-Amanda H.

RE: External input & output on nRF52840

alexa — Thu, 27 Aug 2020 11:28:27 GMT

Hi Amanda Hsieh! I am trying the idea which you suggested me the previous week, but I cannot achieve turning on one LED when supplying '1' (5V). When I change the LEDS_ACTIVE_STATE to 1, the other LEDs remain on for the whole time, without me specifying that. (i.e I don't modify the rest of the code)

In order to debug this, I though of trying to understand these functions, like you suggested:

[quote userid="77782" url="~/f/nordic-q-a/64990/external-input-output-on-nrf52840/265674"] functions like buttons_handler and leds_buttons_init() [/quote]

- but I cannot find them. Could you please tell me in which .c or .h file should I look for them? I also couldn't find this:

[quote userid="77782" url="~/f/nordic-q-a/64990/external-input-output-on-nrf52840/265674"]commenting out Toggle LEDs while loop part[/quote]

- it should probably be in main, but I only see one LED toggling, not more:

#define LEDBUTTON_LED BSP_BOARD_LED_2 /**< LED to be toggled with the help of the LED Button Service. */

Could you plase tell me in which source files should I look for the mentioned functions? Thank you!

RE: External input & output on nRF52840

Amanda Hsieh — Wed, 26 Aug 2020 08:15:53 GMT

See this answer.

-Amanda H.

RE: External input & output on nRF52840

alexa — Tue, 25 Aug 2020 15:02:23 GMT

Hi Amanda. Thanks for your reply, it's helping me.

[quote userid="77782" url="~/f/nordic-q-a/64990/external-input-output-on-nrf52840/265674"]OUT register[/quote]

- how can I access this OUT register on the laptop, specifically? Is it related to the debugging option? Thank you!

RE: External input & output on nRF52840

Amanda Hsieh — Fri, 21 Aug 2020 07:42:11 GMT

Hi Alexa,

[quote user="alexa"]Do you have an idea where I should start to investigate and change the code accordingly? So that, only my desired GPIO or LED turns on at HIGH.[/quote]

You could check the functions like buttons_handler and leds_buttons_init() if they are there. You can test with the Blinky Example by commenting out Toggle LEDs while loop part.

[quote user="alexa"](2) I will do a communication with another board using that GPIO, so I'd like to see what bits are changed and where. So, how could I know what registers get modified, when I set high the value of a specific digital output? (in order for me to actually use that bit change for my communication, further in my project).[/quote]

Not sure I understand what you are trying to do. You can read the OUT register to check if the pin is high or low.

-Amanda H.

RE: External input & output on nRF52840

alexa — Thu, 20 Aug 2020 13:20:03 GMT

Ok, Ms. Amanda Hsieh , thank you for clarifying everything to me. 🙂

[quote userid="77782" url="~/f/nordic-q-a/64990/external-input-output-on-nrf52840/265559"]A8 is P0.31 which means that it can either function as a normal GPIO or as an analog pin.[/quote]

- regarding this I have two questions:

(1) I did the modifications in the pca header and I noticed that the LEDs are active on low, therefore I changed LEDS_ACTIVE_STATE to 1, to make them turn on only on supply. But now, some LEDs remain turned on, some are off (even if I only set 1 LED on). I am not sure what their behaviour depends on. Do you have an idea where I should start to investigate and change the code accordingly? So that, only my desired GPIO or LED turns on at HIGH.

(2) I will do a communication with another board using that GPIO, so I'd like to see what bits are changed and where. So, how could I know what registers get modified, when I set high the value of a specific digital output? (in order for me to actually use that bit change for my communication, further in my project).

Thank you in advance & best regards!

RE: External input & output on nRF52840

Amanda Hsieh — Thu, 20 Aug 2020 12:44:34 GMT

Hi,

[quote user=""]1. Is this the only place where I need to do the modifications? It seems like only a mapping problem to me, but I think I might to re-write other files as well.[/quote]

Right. You need to modify the board header file (nRF5_SDK\components\boards\pca10056.h) to initialize the pin. It is related to how leds_buttons_init() in main.c initializes the buttons. Also, add to buttons_handler and leds_buttons_init() function in main.c:

[quote user=""]2. What do the (xx) need to be? (I read about this mapping in nRF52840's specs, @pag. 525, but I am not sure how to interpret that table into actual code). For instance, let's say that I'd like my A8 pin as a digital output (i.e. drive an external LED). Then, do I need to #define LED_1 NRF_GPIO_PIN_MAP (0, 32)? Or is A8 used already as AIN7, which is actually an analog input (see second line)? [/quote]

A8 is P0.31 which means that it can either function as a normal GPIO or as an analog pin.

-Amanda H.