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12F1572 write program memory issue
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tesla80



Joined: 23 May 2007
Posts: 81

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PostPosted: Wed Dec 10, 2014 1:22 am     Reply with quote
Hi guys.

I use this chip for the 3 independent PWM outputs only. Also price..

I have a PCB and working application with this PIC, so I need to add the byte array feature on this PCB.. I don't have where to run, I'll make it real somehow.

Ttelmah, if you answer my questions in the previous post, it will be much appreciated. I'm going to try that..

EEPROM is a need for this chip... Anyway.
Ttelmah



Joined: 11 Mar 2010
Posts: 20063

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PostPosted: Wed Dec 10, 2014 9:44 am     Reply with quote
No guarantees on this. Haven't a PIC of this type to try.
However 'comments'. Found that the CCS write function would erase the whole 32word page, not 16words in MPLAB. Not sure if this is a fault with the emulation of the code, so rewrote this. Remember interrupts should be disabled before calling:
Code:

//for a const int8 array declared as:
const int8 array[100][3] = {
{1,2,3},{1,2,3},{1,2,3},{1,2,3},{1,2,3},{1,2,3},{1,2,3},{1,2,3},.... //etc.
};

#define ROW_LEN 3

#WORD PMADDR=getenv("SFR:PMADRL")
#bit CFGS=getenv("BIT:CFGS")
#bit FREE=getenv("BIT:FREE")
#bit WREN=getenv("BIT:WREN")
#bit WR=getenv("BIT:WR")
#bit LWLO=getenv("BIT:LWLO")
#byte PMCON2=getenv("SFR:PMCON2")
#word PMDAT=getenv("SFR:PMDATL")

#inline
void unlock()
{
   PMCON2=0x55;
   PMCON2=0xAA;
   WR=TRUE;
   delay_cycles(1);
   delay_cycles(1);
}

#inline
void erase(int16 address)
{
   //directly from the data sheet
   PMADDR=address;
   CFGS=FALSE;
   FREE=WREN=TRUE;
   unlock();
}

void write_page(int16 address, int16 * data, int8 ctr)
{
   //directly from the data sheet
   ctr/=2; //writing in words
   --ctr;
   WREN=TRUE;
   CFGS=FALSE;
   LWLO=TRUE;
   PMADDR=address;
   do
   {
      PMDAT=*data;
      unlock();
      PMADDR++;
      data++;
   } while (--ctr);
   LWLO=FALSE;
   PMDAT=*data;
   unlock();
}
   
void write_byte(int8 x,int8 y,int8 val)
{
   //routine to change a byte in 'array' at x,y with rows 'row_len' long
   int16 address;
   int8 word_address;
   int16 temp_buff[16];
   address=label_address(array); //address of the array start
   //Now calculate the offset
   address=address+((int16)ROW_LEN*x)+y;
   word_address=(address&0xF);
   address&=0xFFF0;
   //Now we have the page address and instruction in the page
   read_program_memory(address,&temp_buff,32); //read page
   //0x34xx is the code for a RETLW instruction
   temp_buff[word_address]=(int16)val + 0x3400; //change the byte
   //write the page back and erase.
   erase(address);
   write_page(address,&temp_buff,32);
}

//So to change byte [80][0] to 43, use:
   write_byte(80,0,43);


Last edited by Ttelmah on Thu Dec 18, 2014 3:34 am; edited 1 time in total
tesla80



Joined: 23 May 2007
Posts: 81

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PostPosted: Thu Dec 11, 2014 3:40 am     Reply with quote
Hi Ttelmah,

I'm going to try your code.

Just a question; do you mean +9 with label_address(array); ?

So I'll locate the array using #org to 0x500 and label_address will give 0x509, correct?

BR
Ttelmah



Joined: 11 Mar 2010
Posts: 20063

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PostPosted: Thu Dec 11, 2014 4:20 am     Reply with quote
There is no point in locating it anywhere. Doing so, will reduce your space available, since then things can't be moved.

As I said already:

"
Declare the variable as:

const int8 array[100][3] = {.........};

Then "label_address(array)" will be the address in ROM where the first instruction of the table is stored."

The 'label_address' function, automatically tells you where the actual data is stored.
tesla80



Joined: 23 May 2007
Posts: 81

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PostPosted: Thu Dec 11, 2014 2:04 pm     Reply with quote
Hello,

I've tried it as below, but the mcu freezes after write.

Code:
  disable_interrupts(GLOBAL);
  write_byte(0,0,50);
  write_byte(0,1,100);
  write_byte(0,2,150);
  enable_interrupts(GLOBAL);
Ttelmah



Joined: 11 Mar 2010
Posts: 20063

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PostPosted: Fri Dec 12, 2014 2:20 am     Reply with quote
So run it up in an ICD, or simulator and work out what is hanging. This is called debugging.
As I said 'no guarantees'. It is based directly on what the data sheet says.
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