maxurs
Joined: 05 Sep 2013
Posts: 1
Location: Italy
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| 12f617 program memory write help |
 Posted: Thu Sep 05, 2013 4:31 am |
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Hi,
I want to use the program memory of a 12F617 to store some data bytes (the chip misses data eeprom but has got program memory self r/w capability).
I have compiler V4.124. I followed the latest CCS manual at page 633 and examples. I am using write_program_memory() and erase_program_eeprom() calls.
I am using address 0x300 to store 8 byte of data. I can write the data only once, if I try to write different data to overwite the previous data I get garbage.
Notice that I am using MPLAB and MPSIM. Cannot test in real hw at the moment, so I don't know if it is a limitation of MPSIM or a problem with my code.
This is the simple code I am using:
| Code: | void main()
{
int ix;
int8 value[16] = {1, 2, 3, 4, 0, 0, 0, 0};
int8 newvalue[16] = {5, 6, 7, 8, 0, 0, 0, 0};
int8 readvalue[16];
ix = getenv("FLASH_ERASE_SIZE"); //returns 32
ix = getenv("FLASH_WRITE_SIZE"); //returns 8
//correct writing: will write 0201 0403 0000 000 at 0x300
write_program_memory(0x300, value, 8);
erase_program_eeprom(0x300); //as per CCS instructions
//wrong writing: this will write garbage at 0x300 (0201 0003 0000 0000)
write_program_memory(0x300, newvalue, 8);
//do nothing
for (;;)
delay_ms(100);
} |
Can anybody help? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Sep 06, 2013 2:14 pm |
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According to the 12F617 data sheet, the PIC is supposed to automatically
erase the flash memory before it writes to it. The 12F617 data sheet says:
| Quote: |
3.4 Writing the Flash Program Memory
When the write is performed on the last word
(PMADRL<1:0> = 11), a block of sixteen words
is automatically erased and the content of
the four-word buffer registers are written into
the program memory.
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The MPLAB simulator doesn't do this. I tested it with CCS vs. 4.141
and MPLAB vs. 8.91 and the flash memory bits are not erased
(set to all 1's) before new data is written. As a result, sequential
calls of write_program_memory() in the simulator do a bitwise
ANDing operation on the flash. This is what you are seeing.
Other people on the MPLAB forum report the same thing:
https://www.microchip.com/forums/tm.aspx?m=602846 |
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