Z8F1680SH020SG Datasheet, PDF (299/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
274
20.3.4. Flash Sector Protect Register
The Flash Sector Protect Register is shared with the Flash Page Select Register. When the
Flash Control Register (see page 271) is written with 5EH, the next write to this address
targets the Flash Sector Protect Register. In all other cases, it targets the Flash Page Select
Register.
This register selects one of the eight available Flash memory sectors to be protected. The
reset state of each Sector Protect bit is an unprotected state. After a sector is protected by
setting its corresponding register bit, it can only be unprotected (the register bit can only
be cleared) by a System Reset. Please refer to Table 132 on page 262 and to Figures 51
through 53 to review how Flash memory is arranged by sector.
Table 137. Flash Sector Protect Register (FPROT)
Bits
Field
Reset
R/W
Address
7
SPROT7
0
R/W
6
SPROT6
0
R/W
5
SPROT5
0
R/W
4
3
SPROT4 SPROT3
0
0
R/W
R/W
FF9H
2
SPROT2
0
R/W
1
SPROT1
0
R/W
0
SPROT0
0
R/W
Bit
Description
[7:0]
Sector Protection
SPROTx • On Z8F2480 devices, each bit corresponds to a KB Flash sector.
• On Z8F1680 devices, each bit corresponds to a 2KB Flash sector.
• On Z8F0880 devices, each bit corresponds to a 1KB Flash sector.
20.3.5. Flash Frequency High and Low Byte Registers
The Flash Frequency High and Low Byte registers, shown in Tables 138 and 139, com-
bine to form a 16-bit value, FFREQ, to control timing for Flash program and erase opera-
tions. 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 frequencies below
32 kHz or above 20 MHz. The Flash Frequency High and Low Byte registers must be
loaded with the correct values to ensure proper operation of the device.
PS025015-1212
PRELIMINARY
Flash Memory