Z8F1601 Datasheet, PDF (165/246 Pages) Zilog, Inc. – Z8 Encore Microcontrollers with Flash Memory and 10-Bit A/D Converter

Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!^®
147
Flash Frequency High and Low Byte Registers
The Flash Frequency High and Low Byte registers combine to form a 16-bit value,
FFREQ, to control timing for Flash program and erase operations. The 16-bit binary Flash
Frequency value must contain the system clock frequency (in kHz) and is calculated using
the following 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 frequen-
cies below 32KHz (32768Hz) or above 20MHz. The Flash Frequency
High and Low Byte registers must be loaded with the correct value to in-
sure proper operation of the Z8F640x family device.
Table 88. Flash Frequency High Byte Register (FFREQH)
BITS
7
6
5
4
3
2
1
0
FIELD
FFREQH
RESET
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ADDR
FFAH
FFREQH—Flash Frequency High Byte
High byte of the 16-bit Flash Frequency value.
Table 89. Flash Frequency Low Byte Register (FFREQL)
BITS
7
6
5
4
3
2
1
0
FIELD
FFREQL
RESET
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ADDR
FFBH
FFREQL—Flash Frequency Low Byte
Low byte of the 16-bit Flash Frequency value.
PS017610-0404
Flash Memory