PWM outputs on Nucleo F401

[espruino-discuss3]

Posted at 2014-12-13 by Rob

According to the reference: http://www.espruino.com/ReferenceNUCLEOF401RE

Pin B15 should output PWM, but analogWrite(B15,...) gives an error:

Error: Pin B15 is not capable of PWM output...
The error also says pin B12 is a PWM output (which doesn't seem to work).
I think there is a mismatch somewhere.

Cheers,

Rob

[espruino-discuss3]

Posted at 2014-12-14 by asez73

Hello Rob,

Are getting the kind of output below?

>reset();
=undefined
 _____                 _
|   __|___ ___ ___ _ _|_|___ ___
|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
          |_| http://espruino.com
 1v72 Copyright 2014 G.Williams
>analogWrite(B12,0.5);
=undefined
>analogWrite(B15,0.5);
ERROR: Pin B15 is not capable of PWM Output
Suitable pins are:
A0 A1 A2 A3 A5 A6 A7 A8 A9
A10 A11 A15 B0 B1 B3 B4 B5 B6
B7 B8 B9 B10 B12 B13 B14 C6 C7
C8 C9
Or pins with DAC output are:
=undefined
>analogWrite(B15,0.5,{freq: 5});
ERROR: Pin B15 is not capable of PWM Output
Suitable pins are:
A0 A1 A2 A3 A5 A6 A7 A8 A9
A10 A11 A15 B0 B1 B3 B4 B5 B6
B7 B8 B9 B10 B12 B13 B14 C6 C7
C8 C9
Or pins with DAC output are:
=undefined
> 

Meanwhile for B12 this code doesn't show any thing special about it.
However the doc doesn't show B12 as a PWM capable pin.
I did not wired anything to it so far.
Do you have an element/clue about what doesn't work with B12?

>analogWrite(B12, 0.5, { freq : 5 });
=undefined
>

Clearly, the specs of STM32F401RE shows that it should work with B15 pin, it's not a matter of hardware.

Actually, Espruino's doc page you mentioned is right. The utilities that generated it are correctly using the pins definitions which are themselves correct too.

However, there seem to be a problem in the source/compiled version of Espruino itself.
To be investigated further I think.

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Posted at 2014-12-15 by @gfwilliams

Thanks - I'll look further into this. It sure seems like it should work - even the generated pin declarations file seems to be correct, so it's something in the interpreter that is failing to work properly (right at the top of the jshPinAnalogOutput function - although I can't see how this could actually fail).

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Posted at 2014-12-15 by @gfwilliams

Ok, this'll be fixed in 1v72.

In fact it was to do with pin names. Any pin past B10 is currently wrong on the Nucleo boards - so that would have broken a whole bunch of stuff :)

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Posted at 2014-12-15 by Rob

Thanks @gfwilliams