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Change PIN at Runtime

 
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PeWa



Joined: 15 Jan 2019
Posts: 22
Location: Sweden

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Change PIN at Runtime
PostPosted: Sat Nov 27, 2021 5:02 am     Reply with quote
In many examples we can use for example a #Define Pin_to_Use PIN_D1.

This is used when compiler generate the code.

However I have seen an example of change the PIN in runtime like this:
Code:

int16 pin_to_use;

pin_to_use=PIN_B0;

output_low(pin_to_use);

pin_to_use=PIN_B1;

output_low(pin_to_use);

But this does not work in my case so I wonder what can go wrong with this type of code in CCS ? It compiles OK but the I/O address is wrong not point to the address defined in header file for the MCU.

Are there other ways to alter the PIN in an output_high(PIN_xx) at runtime maybe ?

I use compiler 5.076 and MCU is a 30F5011.
PeWa



Joined: 15 Jan 2019
Posts: 22
Location: Sweden

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Re: Change PIN at Runtime
PostPosted: Sat Nov 27, 2021 8:43 am     Reply with quote
PeWa wrote:
In many examples we can use for example a #Define Pin_to_Use PIN_D1.

This is used when compiler generate the code.

However I have seen an example of change the PIN in runtime like this:
Code:

int16 pin_to_use;

pin_to_use=PIN_B0;

output_low(pin_to_use);

pin_to_use=PIN_B1;

output_low(pin_to_use);

But this does not work in my case so I wonder what can go wrong with this type of code in CCS ? It compiles OK but the I/O address is wrong not point to the address defined in header file for the MCU.

Are there other ways to alter the PIN in an output_high(PIN_xx) at runtime maybe ?

I use compiler 5.076 and MCU is a 30F5011.


Edited, the variable address is OK. I can change a static LED but it seems that when I change to variable the output / input functions take some more time to compute. Is that the case ??
temtronic



Joined: 01 Jul 2010
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PostPosted: Sat Nov 27, 2021 8:55 am     Reply with quote
doing it as shown ,will require time to get the desired pin and insert into the output function

why not just ...

#DEFINE this_pin PIN_B2;
#DEFINE that_pin PIN_B4;
...
...
output_low(this_pin);
output_low(that_pin);
...
...
it 'should be faster'.....
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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Re: Change PIN at Runtime
PostPosted: Sat Nov 27, 2021 9:23 am     Reply with quote
PeWa wrote:

It seems that when I change to variable the output / input functions take some more time to compute. Is that the case ??

See this post. It shows how much ASM code is required if you use
a variable to pass the CCS pin number.
http://www.ccsinfo.com/forum/viewtopic.php?t=36953&start=3
bkamen



Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA

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PostPosted: Fri Dec 03, 2021 2:29 am     Reply with quote
You can also use the get_env for the PORT and LAT register addresses.

Then build a struct as you like with a default set of values.

Then just write those values to PORT/LAT registers on start up.

You end up configuring an entire register with a single write.

I'd have to go look at an old example to see how much ASM results.... but it should be pretty thin.
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