Do you prefer the low layer (LL) APIs or CMSIS?

[Roman Jasmann]

Hi,

do you prefer the low layer (LL) APIs or direct register access by means of the CMSIS? Why do you prefer your choice?

[waclawek.jan]

If by CMSIS you mean using the symbols defined in the CMSIS-mandated device headers (and not using SPL, as there are users who confuse CMSIS with SPL), then I vote for that.

The reason is, that I see no point in what's effectively is just renaming the registers and in most cases pretending that there are function calls where a single register or a register bit/bitfield is changed. That's just an unnecessary hindrance, as for the user, mapping between the "library" and the RM has to be established.

Unfortunately, in the CMSIS-mandated device headers, ST fails to provide symbols for values for registers bitfields (yet does this haphazardly in the various "libraries").

My personal view, arguable.

JW

[henry.dick]

"do you prefer the low layer (LL) APIs or direct register access by means of the CMSIS? "

the wrong way to use any vendor library is to incorporate such libraries directly into your code. once you do that, your code is no longer portable. instead, I often use a layer that sits in between my application code and whatever libraries, mine or others, LL or SPL. with this approach, you don't have to worry about (LL)API or CMSIS.

[Roman Jasmann]

@henry.dick​ 

You are talking about a hardware abstraction layer (ST's cube HAL is not a real abstraction layer). I'm not asking about HAL APIs, but which approach (CMSIS vs LL) people use in order to implement a HAL. A good software architecture always has got a HAL for the middleware (and application layers). However, in the end each HAL uses either direct register access (by CMSIS), something like ST's cube HAL, or the LL APIs.

https://www.beningo.com/embedded-basics-apis-vs-hals/

[waclawek.jan]

> A good software architecture always has got a HAL for the middleware (and application layers).

... and I thought you are genuinely interested.

JW

[Roman Jasmann]

I am genuinely interested in whether people prefer the CMSIS or the LL Apis.

[henry.dick]

"and I thought you are genuinely interested."

Apparently some of us are not really interested in things we insisted that we are interested in, :-)​