cop8tac9 National Semiconductor Corporation, cop8tac9 Datasheet - Page 17

• Manufacturer Part Number: cop8tac9
• Description: 8-bit Cmos Flash Microcontroller With 2k Byte Or 4k Byte Memory
• Manufacturer: National Semiconductor Corporation

10.0 Functional Description
Bit 0
The COP8 assembler defines a special ROM section type,
CONF, into which the Option Register data may be coded.
The Option Register is programmed automatically by pro-
grammers that are certified by National.
The user needs to ensure that the FLEX bit will be set when
the device is programmed.
The following examples illustrate the declaration of the Op-
tion Register.
Syntax:
[label:].sect
Example: The following sets a value in the Option Register
and User Identification for a COP8TAC9HLQ7. The Option
Register bit values shown select options: Security disabled,
WATCHDOG enabled HALT mode enabled and execution
will commence from Flash Memory.
Note: All programmers certified for programming this family
of devices will support programming of the Option Register.
Please contact National or your device programmer supplier
for more information.
10.5 SECURITY
The device has a security feature which, when enabled,
prevents external reading of the Flash program memory. The
security bit in the Option Register determines, whether se-
curity is enabled or disabled. If the security feature is dis-
abled, the contents of the internal Flash Memory may be
read by external programmers or by the built in
MICROWIRE/PLUS serial interface ISP. Security must be
enforced by the user when the contents of the Flash
Memory are accessed via the user ISP.
If the security feature is enabled, then any attempt to exter-
nally read the contents of the Flash Memory will result in the
value FF (hex) being read from all program locations (except
the Option Register). In addition, with the security feature
enabled, the write operation to the Flash program memory
and Option Register is inhibited. Page Erases are also inhib-
ited when the security feature is enabled. The Option Reg-
ister is readable regardless of the state of the security bit by
accessing location FFFF (hex). Mass Erase Operations are
possible regardless of the state of the security bit.
The security bit can be erased only by a Mass Erase of the
entire contents of the Flash unless Flash operation is under
the control of User ISP functions.
Note: The actual memory address of the Option Register is
dependent on the Flash Memory size and is defined in Table
(Continued)
= 1
= 0
.chip
.sect
.db
.endsect
...
.end
Execution following RESET will be from Flash
Memory.
Flash Memory is erased. Execution following RE-
SET will be from Boot ROM with the MICROWIRE/
PLUS ISP routines.
.db
.endsect
8TAC
option, conf
0x01
start
config, conf
value
;wd, halt, flex
;1 byte,
;configures
;options
17
1, however the MICROWIRE/PLUS ISP routines require the
address FFFF (hex) to be used to read the Option Register
when the Flash Memory is secured.
The entire Option Register must be programmed at one time
and cannot be rewritten without first erasing the entire last
page of Flash Memory.
10.6 RESET
The device is initialized when the RESET pin is pulled low or
the On-chip Power-On Reset is activated.
The on-chip Power-On Reset circuit is provided for compat-
ibility to the ROM based version of this device, but is insuf-
ficient to ensure against inadvertent Flash memory corrup-
tion.
requirements.
Applications which are designed to use either the
COP8TAB9/TAC9 or the COP8TAB5/TAC5 must meet the
Reset requirements of the Flash device.
The following occurs upon initialization:
Port C: TRI-STATE (High Impedance Input)
Port F: TRI-STATE (High Impedance Input)
Port J: Output High
Port L: TRI-STATE (High Impedance Input)
PC: CLEARED to 0000
PSW, CNTRL and ICNTRL registers: CLEARED
SIOR:
ITMR, CLKPS: Cleared
Accumulator and Timer 1:
CWKEN, CWKEDG, LWKEN, LWKEDG: CLEARED
CWKPND, LWKPND: RANDOM
SP (Stack Pointer):
RAM:
ISP CONTROL:
Port G: TRI-STATE (High Impedance Input). Exceptions:
If Watchdog is enabled, then G1 is Watchdog output. G0
and G2 have their weak pull-up enabled during RESET.
UNAFFECTED after RESET with power already applied
RANDOM after RESET at power-on
RANDOM after RESET
Initialized to RAM address 06F Hex
UNAFFECTED after RESET with power already applied
RANDOM after RESET at power-on
UNAFFECTED after RESET with power already applied
RANDOM after RESET at power-on
ISPADLO: CLEARED
ISPADHI: CLEARED
PGMTIM: PRESET TO VALUE FOR 10 MHz CKI
See
Section
FIGURE 10. Reset Logic
10.6.1
External
Reset
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