Why write_configuration_memory doesn't work?

Guest · Posted: Wed Sep 14, 2005 6:02 pm

Hi,

I tried the function write_configuration_memory() and it does not change the contents of config bits. Can anyone help?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Guest · Posted: Thu Sep 15, 2005 8:13 am

Here is the code I use:

int addr[14];

addr[0]=0x20;
addr[1]=0x0F;
addr[2]=0x3F;
addr[3]=0x1E;
addr[4]=0x00;
addr[5]=0x83;
addr[6]=0x81;
addr[7]=0x00;
addr[8]=0x0F;
addr[9]=0xC0;
addr[10]=0x0F;
addr[11]=0xE0;
addr[12]=0x0F;
addr[13]=0x40;
write_configuration_memory(addr,14);

Compiler version:3.227 PCWH

Ttelmah · Guest

Are you sure the bytes are not changing?. The contents of this memory, are only read on reset, so if (for instance), you change the clock configuration, it won't apply till the chip is powered off, and on again.
Also any of the 'protection' bits cannot be cleared by writing. These can only be cleared by a full chip erase.

Best Wishes

erothias · Joined: 15 Sep 2005 Posts: 3

After this instruction is executed, i power off and on again but nothing changes. So strange Sad

Ttelmah · Guest

You haven't answered the question from the other poster. What chip?.

Best Wishes

erothias · Joined: 15 Sep 2005 Posts: 3

oh,sorry

It is 18f4550

Ttelmah · Guest

The 'obvious' possibility then, is that something has left bit 5 of address 30000B set. If this is done, the configuration registers will be write protected, and this can only be cleared in 'program' mode, not from the code itself.

Best Wishes

erothias · Joined: 15 Sep 2005 Posts: 3

Thank you so much, but I still have the same problem. I set the fuse as NOWRTC but it's no good. Really funny Confused

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Tell us exactly what you want to do. What specific Configuration Bits
do you want to change, and why ?