Syntax:
ProgramErase (location)Command Availability:
Available on all Microchip PIC microcontrollers with self-write capability. Not currently available on Atmel AVR.
Explanation:
ProgramErase erases information from the program memory on chips that support this feature. The largest value possible for location depends on the amount of program memory on the Microchip PIC microcontroller, given in the datasheet.
This command must be called before writing to a block of memory. It is slow in comparison to other GCBASIC commands.
Note that it erases memory in blocks/pages — the size varies by device: - Many classic PIC18F devices: typically 64 bytes (32 words) per erase row. - Newer PIC18 Q-series (e.g., PIC18FxxQ43, PIC18FxxQ84): typically 256 bytes (128 words) per erase page. - Other sizes exist on some models (e.g., 512 bytes or larger on certain variants).
Always consult the relevant Microchip PIC microcontroller datasheet for the exact erase page/row size, the required alignment (usually a multiple of the page size), and any restrictions on self-write/erase operations (for example, unlock sequences, or row versus page erase).
Care must be taken with this command, since it can easily erase the program that is running on the microcontroller.
Example:
#chip 18F26K22, 16
Dim EraseLocation As Word
EraseLocation = 0x1000
ProgramErase ( EraseLocation ) ' <<< the ProgramErase instruction
ProgramWrite ( EraseLocation, 1234 )Key line: ProgramErase ( EraseLocation ) — erases the entire row containing EraseLocation before ProgramWrite stores a new value there; skipping this step on most PIC self-write hardware leaves the old bits un-overwritable.
See Also:
- ProgramRead — reading program memory
- ProgramWrite — writing program memory after erasing it
- DATA — defining fixed data instead of writing it at run time
