What CPU is Fitbit using ?

[SunsetRunner]

Just the fact that the interface is choppy by just scrolling left and right (in 2020), seem to reveal a below average CPU and RAM capabilities on the Fit Bit Sense.

I don't know if that influences negatively the HR sensor and other health metrics.

[Rich_Laue]

While using inturrupts I would expect the sensors to maybe impact the smoothness of the display. 

I can't say that I have noticed this. 

A quick search doesn't give any hits on a tear down. 

The manual doesn't give any info. 

[t.parker · Accepted solution]

@SunsetRunner it isn't known (Fitbit never reveals specs if internals) however I would assume it's one of low-powered ARM architecture based CPUs. It was already a case with Ionic (ARM Cortex M4 if I remember correctly). Those CPUs come with some onboard 2D acceleration and are rather inferior to ones used by Apple or Samsung (which are capable of 3D graphics in 60FPS). However, the CPU is one of the reasons why battery lives longer on a single charge. Even old Cortex M4 can render 60fps but by lowering framerate the power consumption drops quite a lot. I remember I measured framerate of Ionic and it was 24FPS (I can't recall exactly but it was below 30FPS and it seemed to be locked that way on purpose). Lowering the framerate shouldn't affect sensors. The data reading can still happen a lot faster if needed (a few times per frame). HR interval is not a problem at all because at best, it's being read every second. I think the same goes to GPS (as far as I remember the timestamps in TCX files, the interval was 1 second). Lowering framerate can affect overall user experience as input may (but doesn't have to) be sampled only when the frame is being updated and redrawn. With 60FPS, the input can be sampled every 0.016sec while with 24FPS every 0.041sec. This is enough, for example, to make tapping-to-wake a chore rather than smooth experience.

To measure FPS at home the simplest way is to use a high-speed camera (like GoPro, with known FPS) which doesn't blend frames (as much RAW format as possible). Then swipe Fitbit UI to trigger the scroll animation. Knowing framerate of the high-speed camera and analysing the recording frame by frame it is easy to calculate the framerate of the Fitbit device. I'm curious myself whether Fitbit still goes with <30FPS.

[CBV2]

I read somewhere that the Versa uses a Toshiba processor. Toshiba! Who knew that they make processors!.  In any event there was an upgrade from the original Versa to the Versa 2 and I noticed a marked improvement in choppiness, smoothness etc.  Maybe the Sense 2 will have an upgrade to the processor. In any event, as noted in this thread I suspect that Fitbit have made a choice between smoothness and battery life, and I for one will sacrifice a bit of smoothness for battery life!

[t.parker]

@CBV2 the Toshiba TZ1201XBG (Versa) is an integrated chipset that comes with Cortex M4F CPU, so basically it's the same as for Ionic. However, Versa 2 probably has a faster CPU (but it's much better hidden, there is nothing on the motherboard that allows identifying the chipset of Versa 2). To be honest, I have no idea why Fitbit is so secretive about the components it uses. The trade-off smoothness <-> battery is quite fair in my opinion. One thing that Fitbit could think about is adding power-saving options which would allow users to decided whether they want to have a smoother experience or longer battery life and "sluggish" UI doesn't need to be a downside on the device that we want to charge every week or so.

[Akaye24]

Thank k you for this as this just came across my Google discover page. And I was instantly upset Fitbit didn't release this info.

https://www.abc15.com/how-to-turn-off-wi-fi-calling-on-android-to-combat-hackers