Can I alter PPAGE????

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Can I alter PPAGE????

NXP Employee
NXP Employee

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Posted: Fri Jul 8, 2005  10:12 am


Hello everyone.......


How to alter PPAGE register manually? without using call and rtc.


Can I load PPAGE register with a value? For example PPAGE = $30 so that I can use it for branch or jump.


Thanks in advance



Posted: Fri Jul 8, 2005  11:52 am


Yes, you can write to it directly.


But you should make 100% sure that you are not executing code which is located at the PPAGE window area from 0x8000 to 0xBFFF. If you change PPAGE from code executing there, the HC12 will execute code from this the new page immediately, so you do not have time to jmp to the new PC anymore.


Using CALL or RTC are the only ways to change the PPAGE and the PC both at once in the same instruction.



Posted: Fri Jul 8, 2005  4:36 pm


Yes, alter PPAGE manually. The same way you would alter any other memory location. I do that with GCC. If you must, just add the asm code:


movb #0x30,0x30


Where the second is the address of PPAGE register?



Posted: Fri Jul 8, 2005  5:08 pm


See response from 11:52 am above

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