CCS C Software and Maintenance Offers
FAQFAQ   FAQForum Help   FAQOfficial CCS Support   SearchSearch  RegisterRegister 

ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to CCS Technical Support
output_a() pin select

 
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion
View previous topic :: View next topic  
Author Message
doguhanpala



Joined: 05 Oct 2016
Posts: 120

View user's profile Send private message

output_a() pin select
PostPosted: Wed Nov 23, 2016 6:51 am     Reply with quote
Hello everyone,

I try to make a 5x5 led matrix and make some figures with it like letters, smiley faces etc. I use 18f2550.

I can do it with output_a() command like this.
Code:
int number=0b00001001;
output_a(number);

But i don't want to use all the pins at the A port because i will use some of the pins for other purposes like pwm.

So i tried this
Code:
int number=0b001001;
output_a(number);

to leave pin7 and pin8 alone. I think it worked. I measured the voltage and it was about 1.5v.
In my code i tried to create a pwm signal, from pin 12 and 13. I looked at the signal with oscilloscope and saw the pwm is generated succesfully.

My question is, is there a way to leave a specific pin alone in output_a() command ? For example i need 14 pin. But i want to use the pin 12 and 13 for pwm, and use the 2 pins i need from b port. So is there way to leave them out of the command output_a() ? Like selecting pins which i can use?
Can i say to the pic, hey i need port a but don't touch pin7 ?

Sorry for bad english and thanks for the help.
jeremiah



Joined: 20 Jul 2010
Posts: 1354

View user's profile Send private message

PostPosted: Wed Nov 23, 2016 7:49 am     Reply with quote
Your method will not leave pin 7 and 8 alone. It will put 0's in them.

You can do:
Code:

if(bit_test(number,5)){output_high(PIN_A5);}else{output_low(PIN_A5);}
if(bit_test(number,4)){output_high(PIN_A5);}else{output_low(PIN_A4);}
if(bit_test(number,3)){output_high(PIN_A5);}else{output_low(PIN_A3);}
if(bit_test(number,2)){output_high(PIN_A5);}else{output_low(PIN_A2);}
if(bit_test(number,1)){output_high(PIN_A5);}else{output_low(PIN_A1);}
if(bit_test(number,0)){output_high(PIN_A5);}else{output_low(PIN_A0);}

I don't have the compiler up to compile check that, but hopefully the idea is clear.

EDIT:
or probably better
Code:

output_bit(PIN_A5,bit_test(number,5));
output_bit(PIN_A4,bit_test(number,4));
output_bit(PIN_A3,bit_test(number,3));
output_bit(PIN_A2,bit_test(number,2));
output_bit(PIN_A1,bit_test(number,1));
output_bit(PIN_A0,bit_test(number,0));
doguhanpala



Joined: 05 Oct 2016
Posts: 120

View user's profile Send private message

PostPosted: Thu Nov 24, 2016 4:08 am     Reply with quote
jeremiah wrote:
Your method will not leave pin 7 and 8 alone. It will put 0's in them.

You can do:
Code:

if(bit_test(number,5)){output_high(PIN_A5);}else{output_low(PIN_A5);}
if(bit_test(number,4)){output_high(PIN_A5);}else{output_low(PIN_A4);}
if(bit_test(number,3)){output_high(PIN_A5);}else{output_low(PIN_A3);}
if(bit_test(number,2)){output_high(PIN_A5);}else{output_low(PIN_A2);}
if(bit_test(number,1)){output_high(PIN_A5);}else{output_low(PIN_A1);}
if(bit_test(number,0)){output_high(PIN_A5);}else{output_low(PIN_A0);}

I don't have the compiler up to compile check that, but hopefully the idea is clear.

EDIT:
or probably better
Code:

output_bit(PIN_A5,bit_test(number,5));
output_bit(PIN_A4,bit_test(number,4));
output_bit(PIN_A3,bit_test(number,3));
output_bit(PIN_A2,bit_test(number,2));
output_bit(PIN_A1,bit_test(number,1));
output_bit(PIN_A0,bit_test(number,0));


Thank you for the warning! I tried to output_high() on pin7 and saw that it becomes zero after the output_a() command. When i saw pwm on pin 13 i thought it leaves them alone. It doesn't, as you said to me.

I understood your method and logic. I will try to use output_high() and manage each led with this command. Thank you again!
Best Wishes

Doğuhan
Ttelmah



Joined: 11 Mar 2010
Posts: 19539

View user's profile Send private message

PostPosted: Thu Nov 24, 2016 5:19 am     Reply with quote
If you set the port for 'fast_io', then you can cheat and use the byte wide I/O.

Code:

//in the setup at the top of the code
#use fast_io(A)

//Now PORTA TRIS is under _[u]your[/u]_ control completely.
    //assuming all the bits are used as outputs.
    set_tris_a(0b00000000); //all eight pins output

    //Then for the bit wide I/O
    output_high(PIN_A7);
    output_high(PIN_A6);

    //to put a byte out on the low 6 bits only:
    output_a((input_a() & 0xC0) | (number & 0x3F));


With fast_io selected this will work even if one or two of the top two bits are inputs (with the TRIS set suitably).

It reads the value currently in the port register, takes the top 2 bits of this, and then combines this with the bottom 6 bits from 'number' and writes this back.
doguhanpala



Joined: 05 Oct 2016
Posts: 120

View user's profile Send private message

PostPosted: Thu Nov 24, 2016 5:58 am     Reply with quote
Thank you so much Ttelmah,

I will go with the first solution for now (because i want to be able use port a and port b at the same time) but i really liked cheating logic.
Display posts from previous:   
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion All times are GMT - 6 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group