Z8F6421PM020SC Datasheet, PDF (203/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
183
While the Flash Controller programs the Flash memory, the eZ8 CPU idles but the system
clock and on-chip peripherals continue to operate. Interrupts that occur when a Program-
ming operation is in progress are serviced once the Programming operation is complete.
To exit Programming mode and lock the Flash Controller, write 00H to the Flash Control
register.
User code cannot program Flash Memory on a page that lies in a protected sector. When
user code writes memory locations, only addresses located in the unlocked page are pro-
grammed. Memory writes outside of the unlocked page are ignored.
Caution:
Each memory location must not be programmed more than twice before an
erase occurs.
The proper steps to program the Flash from user code are:
1. Write 00H to the Flash Control register to reset the Flash Controller.
2. Write the page of memory to be programmed to the Page Select register.
3. Write the first unlock command 73H to the Flash Control register.
4. Write the second unlock command 8CH to the Flash Control register.
5. Re-write the page written in step 2 to the Page Select register.
6. Write Flash Memory using LDC or LDCI instructions to program the Flash.
7. Repeat step 6 to program additional memory locations on the same page.
8. Write 00H to the Flash Control register to lock the Flash Controller.
Page Erase
The Flash memory can be erased one page (512 bytes) at a time. Page Erasing the Flash
memory sets all bytes in that page to the value FFH. The Page Select register identifies the
page to be erased. While the Flash Controller executes the Page Erase operation, the eZ8
CPU idles but the system clock and on-chip peripherals continue to operate. The eZ8 CPU
resumes operation after the Page Erase operation completes. Interrupts that occur when
the Page Erase operation is in progress are serviced once the Page Erase operation is com-
plete. When the Page Erase operation is complete, the Flash Controller returns to its
locked state. Only pages located in unprotected sectors can be erased.
The proper steps to perform a Page Erase operation are:
1. Write 00H to the Flash Control register to reset the Flash Controller.
2. Write the page to be erased to the Page Select register.
3. Write the first unlock command 73H to the Flash Control register.
4. Write the second unlock command 8CH to the Flash Control register.
PS019915-1005
Flash Memory