Need to get 4 independently controllable frequency outputs, PBP can do that?

[Ioannis]

If you can accept frequencies up to only 1KHz, then the PCA9685 chip can output 16 pwm channels and is controlled by I2C bus.

Ioannis

[CuriousOne]

I need 4 outputs simultaneously, at different frequencies and w/o putting any load into "main" code execution.

PCA9685 can output different dutycycle, but not frequency. There are a lot of such IC's with adjustable separate duty cycle, but not frequency (I even have 48 channel monster - LT8500)

[CuriousOne]

The only suitable chips I've found are FM synthesis chips from early computer soundcards, like Yamaha YMF262 or AY-3-8910 But they require extra periphery and are loaded with unnecessary bells and whistles. Looks like CD4536B (4 of them) is the best choice so far.

[Ioannis]

Nice chip this seems. But could not figure out how to use it as an PWM.

Ioannis

[CuriousOne]

I don't need PWM, I need frequency

[Dave]

4 separate PIC's with NCO modules. Done..... Why add unnecessary hardware?

[mpgmike]

4 separate PIC's with NCO modules. Done..... Why add unnecessary hardware?

I have a project I was using 3 PICs for 3 NCOs. I updated it adding a touch screen to replace buttons & LEDs, and while at it, replaced 3 PICs with a single PIC18F27Q43 (have to use MPLABX & XC8 since PBP doesn't yet cover that part). That still leaves one more NCO for you.