Z8F4822AR020SG Datasheet, PDF (199/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
179
Flash Frequency High and Low Byte Registers
The Flash Frequency High and Low Byte registers, shown in Tables 97 and 98, combine
to form a 16-bit value, FFREQ, to control timing for Flash program and erase operations.
The 16-bit Flash Frequency registers must be written with the system clock frequency in
kHz for Program and Erase operations. Calculate the Flash Frequency value using the fol-
lowing equation:
FFREQ[15:0] = FFREQH[7:0],FFREQL[7:0] = -S---y---s--t--e---m------C----l-o---c---k-----F---r--e---q---u---e--n---c---y-
1000
Caution: Flash programming and erasure is not supported for system clock frequencies below
20 kHz, above 20 MHz, or outside of the valid operating frequency range for the device.
The Flash Frequency High and Low Byte registers must be loaded with the correct value
to ensure proper program and erase times.
Table 97. Flash Frequency High Byte Register (FFREQH)
Bit
7
6
5
4
3
2
1
0
Field
FFREQH
RESET
0
R/W
R/W
Address
FFAH
Table 98. Flash Frequency Low Byte Register (FFREQL)
Bit
7
6
5
4
3
2
1
0
Field
FFREQL
RESET
0
R/W
R/W
Address
FFBH
Bit
Description
[7:0]
Flash Frequency High and Low Bytes
FFREQH, These 2 bytes, {FFREQH[7:0], FFREQL[7:0]}, contain the 16-bit Flash Frequency value.
FFREQL
PS019924-0113
PRELIMINARY
Flash Control Register Definitions