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Porting 16F722 code to 16F1527

 
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rovtech



Joined: 24 Sep 2006
Posts: 262

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Porting 16F722 code to 16F1527
PostPosted: Mon Nov 24, 2014 8:33 am     Reply with quote
Code that ran on a 16F722 will not run on a 16F1527.
I tried a simple program to test flashing an output. Some things work, some don't. I thought C was supposed to be transportable within limits but I can't understand why portC=0x00; does not work. The commented out lines work on the 16F722. Setting and clearing pins like RS in this example are the problem and will require extensive editing of my program.
PCM C Compiler, Version 5.019

Code:
#include <16F1527.h>
#FUSES INTRC_IO, NOWDT, PUT, BROWNOUT, MCLR
#use delay(clock=16000000)

#byte portB = 6
#byte portC = 7
#bit RB3 = portB.3
#define RS RB3

// *******************
// Main Function
  void main()
{
set_tris_b (0x00);
set_tris_c (0x00);
while (true)
 {
    output_low (pin_c7);        // this works
    output_B(0x00);             // this works
//    RS=0;                     // does not work
//    portC=0x00;               // does not work
   delay_ms (2000);
    OUTPUT_HIGH (PIN_C7);       // this works
    output_B(0xff);             // this works
//    RS=1;                       // does not work
//    portC=0xff;               // does not work
   delay_ms (2000);
 }
}
// the above blinks pin C7 and all of RBx but the commented-out items do not work
Ttelmah



Joined: 11 Mar 2010
Posts: 19346

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PostPosted: Mon Nov 24, 2014 9:38 am     Reply with quote
Note that all the bits that are directly 'C' work.
It's where you start to not use C, but instead do direct I/O that it goes wrong.
If you use the C function 'output_b' or 'output_c' it'll work.

You are _manually_ setting the address of 'portB' to 6, and 'portC' to 7. Are these the addresses of these ports on the 1527?. Answer. No.

CCS C, 'knows' where portb, and portc are, and correctly accesses these for you if you use it's functions. You are doing direct accesses and getting the addresses wrong.....

In fact the compiler can fill these in for you:
Code:

#byte portB = getenv("SFR:PORTB")
#byte portC = getenv("SFR:PORTC")

The compiler will then look up the addresses of these special function registers, and fill them in for you. It's because you have bypassed C, and assumed that the registers are at the same addresses, that the code doesn't work.....
rovtech



Joined: 24 Sep 2006
Posts: 262

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PostPosted: Mon Nov 24, 2014 11:06 am     Reply with quote
Thanks Ttelmah, I wondered about the port addresses but these have worked for years on various chips. I can now easily correct my program. The test program works when modified to:

Code:
#include <16F1527.h>
#FUSES INTRC_IO, NOWDT, PUT, BROWNOUT, MCLR
#use delay(clock=16000000)

#byte portB = getenv("SFR:PORTB")
#byte portC = getenv("SFR:PORTC")
#bit RS = portB.3

// *******************
// Main Function
  void main()
{
set_tris_b (0x00);
set_tris_c (0x00);
while (true)
 {
    RS=0;                     // works
    portC=0x00;               // works 
   delay_ms (2000);
    RS=1;                     // works
    portC=0xff;               // works
   delay_ms (2000);
 }
}
// the above blinks pin B3 and all of RCx
rovtech



Joined: 24 Sep 2006
Posts: 262

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Include files and variables
PostPosted: Mon Nov 24, 2014 4:33 pm     Reply with quote
I decided to display the values for the ports since the project was an LCD display.
I have the following in an include file of functions, it returns with the correct address of 13 for portB:

Code:
#byte portB = getenv("SFR:PORTB")         // 13


If I try to use portB in my Main program as a constant it is garbage.

Code:
printf (WriteData, "portB=%2u", portB);      // does not work


If I use the following in Main it is correct and 13 is displayed:

Code:
char B = getenv("SFR:PORTB");                             // 13
printf (WriteData, "portB=%2u", B);      // displays “portB=13


Can someone explain what is happening? It seems to be with the way the programs are compiled and linked.

Last edited by rovtech on Mon Nov 24, 2014 7:30 pm; edited 1 time in total
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Mon Nov 24, 2014 4:54 pm     Reply with quote
Quote:
If I try to use portB in my Main program as a constant it is garbage

It's not a constant. It's a variable that you can read/write to.
If you want to write 0x55 to PortB, you do this:
Code:
PortB = 0x55;

So if you put your scope on Pin B0, you would see a high level, and
on pin B1, you would see a low level, and so on.

Since it's a variable, if you want to display the address of it, you do this:
Code:
printf("%lx \r", &PortB);

I am running this in MPLAB simulator, just to save time.

If you run that code, you will get this displayed:
Quote:
000d

That's the address of the variable, and it is correct.
rovtech



Joined: 24 Sep 2006
Posts: 262

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PostPosted: Mon Nov 24, 2014 6:03 pm     Reply with quote
Thanks PCM programmer. It is somewhat obvious now. Somehow I had it in my mind that portB was a pointer to PORT B at address 13 (or 6 on other PICs).
Why does the following work if portB is a variable being overwritten?
Code:

#byte portB = getenv("SFR:PORTB")   // 13
#bit RB0   = PORTB.0
#bit RB1   = PORTB.1
#bit RB2   = PORTB.2
#bit RB3   = PORTB.3
#bit RB4   = PORTB.4
#bit RB5   = PORTB.5
#bit RB6   = PORTB.6
#bit RB7   = PORTB.7


I can display as you suggested but only in Hex as in the top line. I get compile errors if I use the second line:

Code:
 printf (WriteData, "portA=%1x", &portA);

Code:
 printf (WriteData, "portA=%2u", &portA);


or other variations. I would like an integer display.
This works and displays "portA=12"

Code:
char Z;
Z=&portA;
    printf (WriteData, "portA=%2u", Z);
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Mon Nov 24, 2014 7:42 pm     Reply with quote
The RAM and SFR addresses in this PIC are 12 bits. This requires
%lx or %lu to display it properly. I'm not sure why the compiler
allows %x, because it is insufficient. If you do this, it will compile,
but it will only display the lower 8 bits, which is 0x99:
Code:
printf ("RC1REG=%x", &RC1REG);

The correct way is to use %lx, then it displays 0x0199:
Code:
printf ("RC1REG=%lx", &RC1REG);


If you want an unsigned decimal value, then you need to do this:
Code:
printf ("RC1REG=%lu", &RC1REG);
rovtech



Joined: 24 Sep 2006
Posts: 262

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PostPosted: Mon Nov 24, 2014 8:14 pm     Reply with quote
If I use

Code:
    printf (WriteData, "portA=%1u", &portA);


I get "Print format is invalid".
The 1x works only it's hex. Using an intermediate variable and 2u works and 3u gives a leading space.

Code:
    printf (WriteData, "portA=%lu", &portA);


OOPS - that's an ell not a one. Now I get it. l for long
It works.
Thanks, Embarassed
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