Real world benefit of increased pwm frequency.

[SSThing]

Hello everyone. 

Absolute novice here but a lot of reading over the last few days has brought me here. 

I'm currently watching a little robotic project being developed. After a lot of investigation, I am confident that it contains the following :-

Nordic nRF52832 MCU 
DMHC4035LSD H-Bridge
N20 Micro DC Motors Brushed DC x2

QL 701530 Lithium-Polymer cell (3.00 mAh, 3.7V nominal, 1.11 Wh energy output capacity). The robot has been programmed to automatically dock when low charge or when the app is closed or innactive (for xx time). 

It's a whiny little beast, not loud but annoying. To get a rough guesstimate, I recorded the audio and ran it through an app and it indicated it was operating at approximately 1khz (with harmonics at 3khz and 5khz). For its intended purpose, this noise will be very distracting, especially when there are multiple robots operating simultaneously.

Everything I have read so far indicates that increasing the pwm to 12khz and higher (16-18 seems to be a sweetspot) will have a net-positive impact on the components and performance but, most importantly, a definite audible improvement for the end user. These devices will never be in continuous use, it will be along the lines of

idle (variable from a few seconds to several minutes/drive (2-3 sec max)/idle.. repeat...

With a maximum powered up duration of, say 6 hours per day but NEVER continuously active (in other words, in 6 hours there may be 10 games played with an average of 30 driving activations per game but the idle times can and will be highly variable).

In layman's terms, what are your thoughts?

I know it's a very open question but, firstly, am I correct in thinking that these components could handle the pwm increase?

Or could the increase be catastrophic? (Gemini Ai says "no" ).

Any and all thoughts and suggestions are very much appreciated (every day is a learning day).

Thank you. 

[Elfving]

Hi,

I like that you bring us these questions, because that means that you think of DevZone as a place where one could get help for everything related to an nRF. That is great, and what I really want DevZone to be. 

Although for this question I am afraid you would have to ask the manufacturer of the motor, or maybe electronics stack exchange. Or maybe someone else can pitch in here. But I can't comment on this myself unfortunately. 

Regards,

Elfving

[SSThing]

To be honest Elfving, the more I have read the more convinced I am that there are no obstacles (components wise) to the pwm change and that the change would almost certainly result in a net positive increase in performance and end-user enjoyment (which is absolutely vital, no-one wants the distraction of a whiny robot).

I have downloaded the various Nordic apps to my Android tablet and nRF does connect immediately to the device but most of the firmware (understandably) is read only. I'm hoping this means that the firmware was coded with the Nordic sdk. 

[Elfving]

SSThing said:

To be honest Elfving, the more I have read the more convinced I am that there are no obstacles (components wise) to the pwm change and that the change would almost certainly result in a net positive increase in performance and end-user enjoyment (which is absolutely vital, no-one wants the distraction of a whiny robot).

Heheh understood. 

SSThing said:

I have downloaded the various Nordic apps to my Android tablet and nRF does connect immediately to the device but most of the firmware (understandably) is read only. I'm hoping this means that the firmware was coded with the Nordic sdk. 

This I am not 100% sure what you mean by though. Could you expand a bit on this?

Regards,

Elfving

[SSThing]

Of course. 

I was simply (possibly incorrectly) assuming that because the device has this MCU and the nRFConnect app is able to connect to the device and lists various parameters, that it meant that the firmware *was* written using the Nordic sdk?

So, if being able to connect *does* indicate this, I was intending to contact the manufacturer and offer to test the operation of the device (if they were able to provide a copy of the base firmware and the small sections of code I would need to insert to change the pwm).

If that makes sense? 

[Elfving]

Ah no the nRFConnect mobile app (if this is what you are refering to?) just shows all open services and characteristics of a device, that the device happened to make available over Bluetooth. That is not something it can only do on Nordic devices, but all devices that uses Bluetooth.

If you wanted to change the pwm speed using app too, keep in mind that it is not necessarily the case that the device exposes every constant used in the program so that it can be modified using a Bluetooth service. Though if they share the fw with you, thats a different story. Then you would rather modify it by reprogramming it, rather than using Bluetooth.

Regards,

Elfving