How to implement ESP8266 5 kHz PWM?

I need to realise a PWM output with 5 kHz +/- 5%. (Presumably due to a filter circuit into which this feeds over which I have no control.)

Is this realisable with a ESP8266 (ideally with NodeMCU)?

I realise that the software PWM of the ESP8266 has a maximum frequency of 1 kHz while the sigma-delta can be used to implement a PWM with a fixed frequency of about 300 kHz.

So is there a reliable way to achieve 5 kHz? I know some people experimented with the I2S peripheral for waveform output but I am unsure whether it can be used for 5kHz output.

Has anybody looked at into a similar problem before?

Solution

You can also use the hardware SPI interface which has an adjustable clock speed. By writing continuous data, the output waveform appears on SCLK.

I've figured out the abovementioned while creating a knight rider effect with IC 74hc595 on ESP8266, using MicroPython (which is indeed slow, as being a script language). It worked for me up to 4MHz SPI clock speed.

The disadvantage is, for permanent waveform, you need to write data to MOSI forever (as when SPI data buffer goes empty, there is no signal on SCLK anymore).