z8f1621 ZiLOG Semiconductor, z8f1621 Datasheet - Page 198

• Manufacturer Part Number: z8f1621
• Description: High Performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS019921-0308
Caution:
Page Erase
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.
Follow the steps below to program the Flash from user code:
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
8. Write 00H to the Flash Control register to lock the Flash Controller.
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.
Follow the steps below to perform a Page Erase operation:
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.
Each memory location must not be programmed more than twice before an
erase occurs.
step 6
to program additional memory locations on the same page.
Z8 Encore! XP
Product Specification
®
F64XX Series
Flash Memory
184