Write_Program_Memory command:)

[garyzheng]

Now i am pursueing a project for RF link. There is a large amount of data to store, and there is no external EEprom on my board. So i want to store those data into the program memory of PIC16F873.

I try to use the built-in function Write_program_memory(),but it can not work. So could someone give out some sample code for write_program_memory() function which can work. thank you!

[bdavis]

Did you try disabling all interrupts? I heard this was an issue - if interrupts are enabled, then it won't work. I saw a post on this not too long ago.

[garyzheng]

1) If i want to write the data into program memory, that means i had to enable the "Flash memery Writable" in configuration bits. --is it (the #fuse NoProtect ) flag that enable the "flash memory write"?

2)low voltage programming---did i need to enable the low voltage programming during the data writing procession into program memory? because when we use ICD2 to burn the program into chip, the program voltage is 9V, but the common usage for PIC MCU is only 5V.

3) So when i use the function write_program_memory, what is the #fuse flag?



//****************************
char rx_buffer[32];
int *pointer;
pointer = rx_buffer;

while(index<11)
{

write_program_memory(0x0e00+index,pointer[index],2);
index++;
}
//*****************************
part of my code, for writing the data from rx_buffer (RS232) into program memory.

anyone could told me whether there is something wrong with it:)

4) The difference between write_program_eeprom and write_program_memory. From the CCS manual, it looks can achieve the same function, write the data into program memory, but whether there is some difference?

Thank you!!

[bdavis]

Sorry - I can't help you on that one - I haven't directly tried it, but may try it in a few days. You may want to look at the bootloader.c and other bootloaders, and look at their fuse settings since they need to program the memory. Of course it can't be protected, but I believe the PROTECT fuse pertains to externally being able to read the program memory.

[jpa]

[garyzheng]

i will try and look what will happen. But if some one had example code, give me some hints or post some part of code here:)

[garyzheng]

So hehe, after reading some assemble code, i found that we should disable all the interrupts before write the ROM. Thank you for some hints!

[Mark]

[garyzheng]

when I write the data sentence by sentence into ROM, it can work. But when i write the data like a stream, it can only wirte the first sentence, after that , it can not work?

because the data is transmitted by RS232(BAUD RATE= 9600) from PC
I wonder whether the Writing procession into ROM should consume some time, but the data stream transmission from RS232 is too faster than the writing procession of ROM, so that cause the error:)

so someone meet that problem before, and could some one told me how many time the Write_program_memory will take:)

thank you!

[Neutone]

Why not write a test program that writes to program memory without the serial link. Break the problem down. If you can write a series of constants to program memory you can be sure the problem is or is not the function to write to program memory. You can read the HEX file from the chip after it runs and see if it is working.

[Mark]

Yes writing to the flash takes some time. Look at the datasheet for the time required.

[garyzheng]

i will try to delay the package transmission from PC

[garyzheng]

Now my program can work by receiving and store the data into program memory package by package. But now I found a weird problem.


**************part of my program*************
if( (rx_preamble[0]=='S') && (rx_preamble[2]=='1')) // screen 1
{
if( (rx_preamble[5]=='A') && (rx_preamble[7]=='1'))
{
storecount=11;
startadd=0x0d00;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='A') && (rx_preamble[7]=='2'))
{
storecount=11;
startadd=0x0d10;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='A') && (rx_preamble[7]=='3'))
{
storecount=5;
startadd=0x0d20;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='A') && (rx_preamble[7]=='4'))
{
storecount=15;
startadd=0x0d30;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='B') && (rx_preamble[7]=='1'))
{
storecount=11;
startadd=0x0d40;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='B') && (rx_preamble[7]=='2'))
{
storecount=10;
startadd=0x0d50;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='B') && (rx_preamble[7]=='3'))
{
storecount=10;
startadd=0x0d60;
store16(storecount,startadd);
return;
}
if ( (rx_preamble[5]=='B') && (rx_preamble[7]=='4'))
{
storecount=10;
startadd=0x0d70;
store16(storecount,startadd);
return;
}
else
{
return;
;
}
}
**********************************************

I store several different infomation into program memory from address 0x0d00 to 0x0df0. Every time I store one of the infomation(such as I store the info into address 0x0db0), the infomation stored in the lower address(such as 0x0dc0,0x0dd0,0x0de0) will change. Some strange character will shift from the upper address.

some one met this problem before, give me some idea:)

another question is for the write procession time. I know that the flash memory writing time is about 4ms to 8ms for one word. During the writing procession , MCU should shut down the interrupts. my method is to give out 100ms delay before enable the global interrupts. But sometimes it can work, but sometimes, i can not work.

can some one give out some good ideas, thank you:)

[garyzheng]

thank you!

[Neutone]

Are you by chance attempting to write across page boundries? You may only write one page at a time and your packet size should be based on the page size.