nRF52 direct access to EasyDMA

[Shlomo Zippel]

Hello,

Is it possible to use EasyDMA directly with nRF52 SDK without using one of the higher level libraries that use it, i.e SPI / UART? I am interested in implementing something similar to Octows2811.

I also looked at the PWM module for this but it seems like it has a max frequency of 200 kHz which is too slow for what I am trying to do.

Thanks!

[RK]

Of course you can - it's all documented in the manual - you just set up the registers and let it roll.

Note that EasyDMA has quite a few anomalies on the preview chips, so ensure you're using hardware resources which are actually working.

[Shlomo Zippel]

Can you please point me to the right location in the docs or register name? All I can find are specific uses of it for SPI / UART etc but not the underlying EasyDMA registers

[RK]

There are no underlying EasyDMA registers, there are various peripherals which use EasyDMA and you access EasyDMA via their registers for that peripheral instance. By 'higher level libraries' did you actually mean 'hardware peripherals', because they're rather different concepts?

No you cannot use EasyDMA outside of a hardware peripheral.

[Shlomo Zippel]

Yes, I meant hardware peripherals. So if I use EasyDMA via SPIM I am limited to the frequencies that SPI supports, right?

[RK]

Yes if you use EasyDMA via any hardware peripheral you are limited to the speeds it supports and the output formats it's designed to produce.

Does the PWM module really only support up to 200kHz for from-memory waveforms? I haven't read the whole thing, I've started a few times and decided to get back to it when I really need it as it's rather dense. Certainly you can run it much faster, but I haven't seen the limitations on arbitrary waveforms.

[Shlomo Zippel]

From PWM docs: "PWM frequency is limited to 200 kHz (5 microseconds period). Exceeding this value might introduce glitches in the output signal."