EXECCTRL_JMP_PIN referenced but not explained #242

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opened 2021-03-08 14:39:10 -06:00 by dghoti · 6 comments

dghoti commented

2021-03-08 14:39:10 -06:00

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"EXECCTRL_JMP_PIN" is refernced 3 times in the SDK without an explanation of how/where to set it.
[ https://datasheets.raspberrypi.org/pico/raspberry-pi-pico-c-sdk.pdf page 59 ]

I did eventually find: static void sm_config_set_jmp_pin (pio_sm_config *c, uint pin) but it is a different call and the two are not linked.
[https://datasheets.raspberrypi.org/pico/raspberry-pi-pico-c-sdk.pdf page 148, 152 ]

maybe explain "EXECCTRL_JMP_PIN" better, or change the reference to "sm_config_set_jmp_pin"

[Edit: corrected the page numbers to the ones on the page, not the literal PDF page]

"EXECCTRL_JMP_PIN" is refernced 3 times in the SDK without an explanation of how/where to set it. [ https://datasheets.raspberrypi.org/pico/raspberry-pi-pico-c-sdk.pdf page 59 ] I did eventually find: static void sm_config_set_jmp_pin (pio_sm_config *c, uint pin) but it is a different call and the two are not linked. [https://datasheets.raspberrypi.org/pico/raspberry-pi-pico-c-sdk.pdf page 148, 152 ] maybe explain "EXECCTRL_JMP_PIN" better, or change the reference to "sm_config_set_jmp_pin" [Edit: corrected the page numbers to the ones on the page, not the literal PDF page]

lurch commented

2021-03-08 16:15:31 -06:00

(Migrated from github.com)

EXECCTRL_JMP_PIN is the JMP_PIN field of the SM0_EXECCTRL, SM1_EXECCTRL, SM2_EXECCTRL & SM3_EXECCTRL Registers described on page 395 of the RP2040 Datasheet .
Unfortunately the fields / registers aren't always referenced in exactly the same manner throughout our documentation, but it sounds like in this particular case if you searched for "jmp_pin" you would have found what you were looking for?

`EXECCTRL_JMP_PIN` is the `JMP_PIN` field of the `SM0_EXECCTRL`, `SM1_EXECCTRL`, `SM2_EXECCTRL` & `SM3_EXECCTRL` Registers described on page 395 of the [RP2040 Datasheet](https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf) . Unfortunately the fields / registers aren't always referenced in exactly the same manner throughout our documentation, but it sounds like in this particular case if you searched for "jmp_pin" you would have found what you were looking for?

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dghoti commented

2021-03-08 17:08:49 -06:00

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I did search for jmp_pin which is how I found the example I quoted above - as a complete beginner in programming and my first attempts at using the pico, I found the reference for this in the SDK very confusing, until I found (and guessed) that it could be set with the sm_config_set_jmp_pin() function.
The description on page 395 of the RP2040 datasheet is even more confusing for me - I would have preferred if the mention of it in page 59 of the SDK had shown how to set or use it, or even referenced the function on 148/152.
No need to go to the RP2040 datasheet, as it is already in the SDK (which is the document that referenced it)

I did search for jmp_pin which is how I found the example I quoted above - as a complete beginner in programming and my first attempts at using the pico, I found the reference for this in the SDK very confusing, until I found (and guessed) that it could be set with the sm_config_set_jmp_pin() function. The description on page 395 of the RP2040 datasheet is even more confusing for me - I would have preferred if the mention of it in page 59 of the SDK had shown how to set or use it, or even referenced the function on 148/152. No need to go to the RP2040 datasheet, as it is already in the SDK (which is the document that referenced it)

lurch commented

2021-03-08 17:33:19 -06:00

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Complete beginners are much better served by MicroPython https://www.raspberrypi.org/documentation/rp2040/getting-started/#getting-started-with-micropython which also lets you use PIO if you want. (Although unfortunately the MicroPython documentation still has gaps https://github.com/micropython/micropython/issues/6855 )

As "a complete beginner in programming", PIO probably isn't your best starting point!! It's a fairly advanced topic. And if you don't reference the RP2040 datasheet at the same time as the SDK documentation, I suspect you may find the SDK documentation even harder to understand. Complete beginners are much better served by MicroPython https://www.raspberrypi.org/documentation/rp2040/getting-started/#getting-started-with-micropython which also lets you use PIO if you want. (Although unfortunately the MicroPython documentation still has gaps https://github.com/micropython/micropython/issues/6855 )

dghoti commented

2021-03-08 17:47:10 -06:00

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I was merely trying to provide some feedback.
I have managed to figure it out (as stated above) but it too me a few hours as the SDK mention of it was rather obscure in my opinion.
maybe "complete beginner" is the wrong phrase, I do know my way around C a bit, which is why I prefer to use C over Python - which while I know is a popular language, I tend to prefer to avoid where possible.
I do realise I am taking the harder path here, but I do prefer to stick to languages with which I am more familiar - the PIO assembly is giving me a hard time, but at least I can follow it and (to a degree) bend it to my purposes, though some others might not be as tenacious as myself - My belief was that the SDK was there to provide a reference, but to only mention setting the jump pin once, and not tie it to the part of the SDK that shows how seems to be a limitation.
I am only trying to provide some feedback that might help provide clarity for others - since I have (eventually) found my own solution - which I had mentioned in the very first post.
I guess next time, Ill just keep my mouth shut - apologies if I have caused any offense by my suggestions - I was simply trying to help.
Thank you for your comments lurch, but I dont feel they were helpful or particuarly relevant to the issue I thought I was highlighting,

I was merely trying to provide some feedback. I have managed to figure it out (as stated above) but it too me a few hours as the SDK mention of it was rather obscure in my opinion. maybe "complete beginner" is the wrong phrase, I do know my way around C a bit, which is why I prefer to use C over Python - which while I know is a popular language, I tend to prefer to avoid where possible. I do realise I am taking the harder path here, but I do prefer to stick to languages with which I am more familiar - the PIO assembly is giving me a hard time, but at least I can follow it and (to a degree) bend it to my purposes, though some others might not be as tenacious as myself - My belief was that the SDK was there to provide a reference, but to only mention setting the jump pin once, and not tie it to the part of the SDK that shows *how* seems to be a limitation. I am only trying to provide some feedback that might help provide clarity for others - since I have (eventually) found my own solution - which I had mentioned in the very first post. I guess next time, Ill just keep my mouth shut - apologies if I have caused any offense by my suggestions - I was simply trying to help. Thank you for your comments lurch, but I dont feel they were helpful or particuarly relevant to the issue I thought I was highlighting,

lurch commented

2021-03-09 04:30:06 -06:00

(Migrated from github.com)

Hello @dghoti

I'm sorry if my reply came across a bit blunt last night, perhaps I was too tired and being overly-defensive 🙁 I'm afraid your "complete beginner in programming" threw me a bit!

We do welcome feedback and suggestions, thank you for pointing out which parts of our documentation you found confusing / lacking 👍

Hello @dghoti I'm sorry if my reply came across a bit blunt last night, perhaps I was too tired and being overly-defensive :slightly_frowning_face: I'm afraid your "complete beginner in programming" threw me a bit! We **do** welcome feedback and suggestions, thank you for pointing out which parts of our documentation you found confusing / lacking :+1:

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dghoti commented

2021-03-09 04:36:46 -06:00

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Hi @lurch,

Its all good - maybe I understate my programming abilities as I still consider myself an amatuer (compared to a lot of what I see here). Mistakes were made on my side too - you're a good egg!

Hi @lurch, Its all good - maybe I understate my programming abilities as I still consider myself an amatuer (compared to a lot of what I see here). Mistakes were made on my side too - you're a good egg!

❤️ 1