Z8F4822AR020SG Datasheet, PDF (193/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
173
Observe the following procedure to setup the Flash Sector Protect Register from user
code:
1. Write 00H to the Flash Control Register to reset the Flash Controller.
2. Write 5EH to the Flash Control Register to select the Flash Sector Protect Register.
3. Read and/or write the Flash Sector Protect Register which is now at Register File
address FF9H.
4. Write 00H to the Flash Control Register to return the Flash Controller to its reset state.
Flash Write Protection Option Bit
The Flash Write Protect option bit can be enabled to block all program and erase opera-
tions from user code. For more information, see the Option Bits chapter on page 180.
Byte Programming
When the Flash Controller is unlocked, writes to Flash memory from user code will pro-
gram a byte into the Flash if the address is located in the unlocked page. An erased Flash
byte contains all ones (FFH). The programming operation can only be used to change bits
from one to zero. To change a Flash bit (or multiple bits) from zero to one requires a Page
Erase or Mass Erase operation.
Byte programming can be accomplished using the eZ8 CPU’s LDC or LDCI instructions.
For a description of the LDC and LDCI instructions, refer to the eZ8 CPU Core User Man-
ual (UM0128), which is available for download on www.zilog.com.
While the Flash Controller programs 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 after 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 resides in a protected sector.
When user code writes memory locations, only addresses located in the unlocked page are
programmed. Memory writes outside of the unlocked page are ignored.
Caution: Each memory location must not be programmed more than twice before an erase occurs.
Observe the following procedure 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.
PS019924-0113
PRELIMINARY
Operation