RSCS

[Aimek]

Hi, 

I am new to DevZone as well as BLE development itself. I am currently working on a project and trying to undestand the IDE as well as the processes and workflow of the nRF52840 DK. 

I was trying to make a counter application and have seen that RSCS has most of the functions needed. I am developing in SEGGER Embeded Studio. 

I have struck uppon further problems:

1. How do you change the names of services, that show up in nRF connect for mobile?

2. In RSCS example you could see the variable - Candence, when I set it up to count from 0 to 256000 (for example) it counts up until 255, which I guess has to do something with the data length limit... So where do I change the size of data which could be transfered, so that it would count to a higher number

P.S. I am new to BLE so if something is not defined in correct terms please ask back, I would reply as soon as possible

[Einar Thorsrud]

Hi,

1. How do you change the names of services, that show up in nRF connect for mobile?

That is not possible. The services are known by their standardized UUID, and the name is not specified anywhere in the nRF. The nRF Connect application simply uses the official Bluetooth name for the specific service. For custom services (except those known to the app, like the Nordic UART Service), the just the UUID will be shown. If you want a specific name shown, you need to make your own mobile application that does it.

2. In RSCS example you could see the variable - Candence, when I set it up to count from 0 to 256000 (for example) it counts up until 255, which I guess has to do something with the data length limit... So where do I change the size of data which could be transfered, so that it would count to a higher number

The cadence is a 8 bit number, so 255 is the maximum value. This follows from the service specification, which you can download from the Bluetooth SIG. If you were to change this to a larger type, you would break the Bluetooth specification, and it would not be compatible with other devices that support running speed and cadence service.

[Aimek]

Thank you for the reply, I undestood the issue with the first part. 

Regarding the second point, I have experimented a little bit more with the RSCS example and have discovered that if you change the stride length increment, it counts numbers with floating points (F.E. "123.45; 123.46; 123.47 ... and so on") and your answer confirms my suspision that the stride length is set to uint16_t, which is coded in ble_rscs.c part of the rscs example. 
And now I have gotten the question: How in the RSCS example was the floating point number set? 

// Instantaneous stride length field
if (p_rscs->feature & BLE_RSCS_FEATURE_INSTANT_STRIDE_LEN_BIT)
{
if (p_rsc_measurement->is_inst_stride_len_present)
{
flags |= RSC_MEAS_FLAG_INSTANT_STRIDE_LEN_PRESENT;
len += uint16_encode(p_rsc_measurement->inst_stride_length,
&p_encoded_buffer[len]);    // <----------- is it because of this part???
}
}

P.S. i was trying to insert code, but i guess my connection timed out 

I was trying to play around, the bits and definitions but I have either gotten an error or my increment would not work as it is supposed to work. 

And as I have said in my request I am trying to make a counter like in this example but simpler, which adds up 1 each second and shows up in the nrf connect for mobile like rscs example does it, but I did not undestand this part in the request

/* I tried to use the timer API and increment the counter in the event handler call back */

I remember reading about something regarding timer APIs' but I have no idea how to implement it in practice and as I undestand this would solve my problem. Could you explain a bit what should I do?

Thank you in advance

[Einar Thorsrud]

Hi,

Aimek said:

And now I have gotten the question: How in the RSCS example was the floating point number set? 

As you write, the stride length is a unsigned 16 bit integer, not a floating point. As with all other aspects of the RSCS, this is given by it's specification and cannot be changed. So it is never a floating point. However, a user of the data (like an app) could very well present the data as floating point.

Aimek said:

I remember reading about something regarding timer APIs' but I have no idea how to implement it in practice and as I undestand this would solve my problem. Could you explain a bit what should I do?

If you just want a timer that counts seconds, and do not need finer granularity then that, I would simply use the application timer library and use a 1 second repeated timer. You can refer to the documentation and (slightly outdated) tutorial to see how it is used.

I am a bit confused as it seems you are trying to mold the RSCS into something it is not. What is your end goal? Is it to use RSCS, or is it to make another (custom) service, and you just happened to use that as a starting point? If you can back-track a bit and describe what you want to accomplish, it might be that I could make some sensible suggestions.

[Aimek]

Hi,

so I am trying to implement the UART example with some sort of data transmition as a prototype, to just discover the limitations of the nRF52840 (regarding the connecton distance and data transfered), but as I am relatively new to BLE this is quite a challenge. I was trying to figure out how to combine the UART example with a simple nfc record URL (just for a test as well), but after checking al the libraries and directories and compiling it stopped advertising and nothing worked. So I have just thought to use an already existing example, because it resembles my goal quite a lot. For now I think I would be trying to make a study on how to make it possible to write something into console from the mobile device itself (like in uart example), so pretty much, how to add a writting into console function via mobile device into the rscs example.

P.S if there is such example already existing would be great to hear about it because I could not find it

[Einar Thorsrud]

Hi,

Aimek said:

I am trying to implement the UART example with some sort of data transmition as a prototype, to just discover the limitations of the nRF52840 (regarding the connecton distance and data transfered

Is it so that with regard to Bluetooth you just want a data channel? If so, I suggest you take a look at the Nordic UART service (NUS). There are both central and peripheral examples for that in both the older nRF5 SDK and the newer nRF Connect SDK. The service simply provides data channels to mimic UART over BLE. This can also work as an example of a simple custom service that you can adapt to your need, but many end products in fact ship with that more or less unmodified, perhaps only with another UUID.

Aimek said:

So I have just thought to use an already existing example, because it resembles my goal quite a lot.

It is not really the case. The RSCS example very specifically implements the RSCS profile, and it is not a good starting point for what you describe. This is where NUS comes in.

Aimek said:

I was trying to figure out how to combine the UART example with a simple nfc record URL (just for a test as well

As you have been using nRF5 SDK before in this thread, I will assume that you are still using that for now. In that case, the SoftDevice must be used, so I would take the BLE example as starting point, and migrate the NFC code into it. Remember to also update the sdk_config.h to enable NFC related libraries etc (you may need to copy-past parts from the NFC example here also).

[Aimek]

Hi again,

I would look into NUS, thank you for the advice