I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

awneil — Thu, 05 Sep 2019 08:03:02 GMT

You're welcome.

If the issue is now resolved, please verify the answer:

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Thu, 05 Sep 2019 01:59:04 GMT

It's indeed the problem of my design. But I have solved that problem with Edvin's help. Thank you very much for your insistent attention to my problem.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Thu, 05 Sep 2019 01:56:32 GMT

That's exactly what I mean. I solved the problem with your help. Thank you very much for your kindly help these days.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

Edvin — Tue, 03 Sep 2019 09:27:19 GMT

Ok, I see.

The issue is that you are handling your entire countdown in the nus_data_handler(). Hence, when a new number enters, it is not able to handle that callback until you finish the handler that you are in now. They are two equal events with the same priority, so the new number is not called until the previous has returned.

I suggest you do something like this:

volatile uint32_t time_now_s = 0;       // remember to use volatile
volatile bool start_countdown = false;  // remember to use volatile
static void nus_data_handler(...)
{
    if (p_evt->type == BLE_NUS_EVT_RX_DATA)
    {
        time_now_s = atoi((char*)p_evt->params.rx_...;
        start_countdown = true;
    }
}

static void start_my_countdown()
{
    while(time_now_s > 0)
    {
        time_now_s--;
        ...
    }
}

main()
{
    ...
    for(;;)
    {
        if(start_countdown)
        {
            start_my_countdown();
            start_countdown = false;
        }
    }
}

But that is also not perfect. You should really use a timer that has a timeout of 1 second or whatever resolution you need, and use the timeout handler to decrement time_now_s and update the display. This way, you will allow the nRF to go to sleep to save some power while you are running the countdown as well.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

awneil — Tue, 03 Sep 2019 08:29:26 GMT

[quote userid="83013" url="~/f/nordic-q-a/51654/i-am-using-the-nrf2840-and-waveshare-s-2-9-epaper-display-to-make-a-cutdown-tool-but-i-am-facing-some-problems/207533"] I just can't abort the countdown[/quote]

Why not?

What's the problem?

Why would that be a problem?

It's your code that does the countdown - so you should know how to abort it!

Can you get this working on its own - without the added complication of BLE?

It sounds like a problem with your system design ...

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Tue, 03 Sep 2019 06:12:48 GMT

I have update some of my code in the reply to Edvin. Maybe that will help you to understand my thoughts. I just can't abort the countdown, maybe it's because of that the Nordic UART Service is FIFO?

Thank you for your continuous attention to my questions.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Tue, 03 Sep 2019 06:05:11 GMT

Yes, this is exactly what I mean. I want to abort the current countdown and start it with the new number. But I don't know how to realize this function. I just rewrite the nus_data_handler() function with a very easy logic. I changed the receive data into int, and let it decrease. The code is like this:

static void nus_data_handler(ble_nus_evt_t * p_evt)
{
     if (p_evt->type == BLE_NUS_EVT_RX_DATA)
    {
    
        int time_now_s;

        time_now_s=atoi((char*)p_evt->params.rx_data.p_data);
        ...
        ...
        ...
         while(time_now_s>0) 
		 {
            time_now_s--;
            ...
            ...
            ...

And the service_init() function is like this:

static void services_init(void)
{
    uint32_t           err_code;
    ble_nus_init_t     nus_init;
    nrf_ble_qwr_init_t qwr_init = {0};
	//	ble_nus_evt_t *pp_evt;

    // Initialize Queued Write Module.
    qwr_init.error_handler = nrf_qwr_error_handler;

    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init);
    APP_ERROR_CHECK(err_code);

    // Initialize NUS.
    memset(&nus_init, 0, sizeof(nus_init));
	
	
    nus_init.data_handler = nus_data_handler;
	
    err_code = ble_nus_init(&m_nus, &nus_init);
    APP_ERROR_CHECK(err_code);
}

I don't know whether these code will help you to understand my meanings or not.

Thank you for your continuous attention to my questions.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

awneil — Mon, 02 Sep 2019 09:37:35 GMT

You mean the Nordic UART Service (NUS) ?

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/group__ble__nus.html

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/ble_sdk_app_nus_eval.html

As Edvin says, that gives you an Event when data is received.

So it's up to your code to do whatever you want when that Event occurs.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

Edvin — Mon, 02 Sep 2019 09:30:33 GMT

When you write a new number it will replace the old number in the service. If the counter isn't updated, then that is because of how you treat it in your application.

The nus_data_handler() is called when you "refresh" the number by sending the number to your characteristic. How you use this number after that is up to the application. I don't know how you use this event, and how you start your countdown, but it sounds like you need to abort the current countdown, and start it again with the new number.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

awneil — Mon, 02 Sep 2019 09:29:47 GMT

It's still unclear what your actual problem is:

Transferring the new number over BLE to your module?
In your module firmware, getting access to the new number?
Writing the new number onto the display?
Other ... ?

Again, the question of how to write to and update the display has nothing to do with Nordic: the display neither knows nor cares what microcontroller you use - it works the same whatever is driving it.

Therefore, you need to go to the display documentation, and/or the manufacturer, for details of how to control the display.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Mon, 02 Sep 2019 09:20:50 GMT

I am using the bluetooth uart module. I wish the new number would replace the old one immediately. But now the number will replace when the old one decreases to 0. I wonder if the NRF52840 module is preemptive or not and how to realize this function.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

Edvin — Mon, 02 Sep 2019 09:06:14 GMT

[quote user="leo li"]For example, I have passed a number and the number is decreasing on the e-paper. But now I want to restart the cutdown with a new number, how could I realize this function.[/quote]

Probably the same way that you sent the number the first time. How did you do that? And what happens if you try to refresh the number the same way that you did earlier?

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Mon, 02 Sep 2019 08:52:47 GMT

Thank you for your reply. I am sorry that I don't describe my question very clearly. I have update my question in the previous answers by awneil. You can go to that answer to know further things. Thank you very much.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

leo li — Mon, 02 Sep 2019 08:41:03 GMT

I want to use the Bluetooth module of the NRF52840 to make a remote control cutdown tool. So I use the mobile APP to send numbers to the NRF52840. This is the meaning of the "published". The problem is that I don't know how to reflesh the number.

For example, I have passed a number and the number is decreasing on the e-paper. But now I want to restart the cutdown with a new number, how could I realize this function.

Thank you very much for your timely reply.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

Edvin — Mon, 02 Sep 2019 08:37:29 GMT

I don't know your setup Leo, but if the issue is that the numbers are stacked on top of each other, it sounds like you need to clear the screen first. How you do that, I don't know, but it is probably documented somewhere around the same place as you found out how to write to the epaper display.

RE: I am using the NRF2840 and WaveShare's 2.9 epaper display to make a cutdown tool, but I am facing some problems.

awneil — Mon, 02 Sep 2019 08:23:19 GMT

[quote userid="83013" url="~/f/nordic-q-a/51654/i-am-using-the-nrf2840-and-waveshare-s-2-9-epaper-display-to-make-a-cutdown-tool-but-i-am-facing-some-problems"]the number I have published[/quote]

What do you mean by "published" here?

What do you mean by that?

You mean, how to update the display?

That has nothing to do with Nordic - you need to contact the display manufacturer (WaveShare?) for that.