[sdiy] Driving SSI2144 freq control with PWM from a microcontroller

[bbob]

on  a completely different track, i've been eyeing the TC2644 and LTC2645
dedicated PWM-voltage converter chips:
https://www.analog.com/en/technical-articles/accurate-fast-settling-analog-voltages-from-digital-pwm-signals.html


On Sat, Nov 5, 2022 at 11:03 AM <rburnett at richieburnett.co.uk> wrote:

> >> The easiest way to get PDM is just to reverse the bits from the PWM
> >> counter to the PWM comparator, but not all MCUs support this mode.
> >
> > Oooh, that's clever! I'd never seen that before. That should
> > *absolutely* be a hardware feature on every chip with PWM...
>
> I haven't noticed this as a hardware feature in the PWM peripherals of
> any microcontrollers that I've worked with in the past, but it would
> definitely be a worthwhile addition.  Also, easy enough to implement in
> an FPGA where you're designing your own hardware.
>
> Tom, I suspect that one of the reasons why it's not more common is that
> most users of microcontrollers with PWM are doing "power electronics"
> type stuff...  Chopping up large currents to drive motors, dim LED
> lighting or otherwise convert power of one kind into another.  In
> conventional power-electronics applications every switching transition
> represents energy loss, decreased efficiency and heat that must be got
> rid of, so you certainly wouldn't want more than the minimum (2)
> transitions in every cycle.
>
> So, it's a nice technique for shaping the switching noise and pushing it
> up the frequency spectrum in audio applications, but probably not high
> on the wish-list of the typical customer using built-in PWM peripherals
> for general power applications.
>
> -Richie,
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