gc80c520a CORERIVER Semiconductor, gc80c520a Datasheet - Page 73

• Manufacturer Part Number: gc80c520a
• Description: Midas1.0 Family Mask Rom/eprom/romless 8-bit Turbo Microcontrollers
• Manufacturer: CORERIVER Semiconductor

Power Down state. The high on RST pin terminates the Power Down mode, and restarts the clock. The
program execution will restart from 0000H. Because the clock stops in the Power Down mode, the
Watchdog timer cannot be used for exiting the Power Down mode.
The MiDAS1.0 family can be woken from the Power Down mode by activating an enabled external, when
the global enable (EA) bit is set to 1 and the external interrupt was set to the level sensitive mode. If these
conditions are satisfied, the low level on the external interrupt pin restarts the oscillator. The external
interrupt pin should be held to “0” for at least 65,536clocks. Because of crystal stabilization time, 65,536
clocks must be needed to wake-up from the power down mode. After 65,536 clocks, system clock will be
running normally and interrupt logic will start the external interrupt. Then the processor will execute the
interrupt service routine for the corresponding external interrupt. After the interrupt service routine is
completed, the processor will go beyond the instruction that put it into the Power Down mode and it will
start execution from the next instruction.
6.2.12 EPROM
The programming and verifying timing is very similar to that of Intel 80C52. The MiDAS1.0 family
programs at V
To erase the EPROM, the MiDAS1.0 family must be exposed for 20 minutes in UV-light (15mW/cm
A 44-PLCC or 44-MQPF device may require an additional adaptor to program the EPROM.
In some applications, it is desirable that the Program Memory be secure from software piracy. The
MiDAS1.0 family has varying degrees of program protection using Encryption array or lock bits.
6.2.12.1 Encryption Array
Within the EPROM is an array of encryption bytes that are initially unprogrammed (all 1’s). For EPROM
Power Down
Mode
IDLE
MiDAS1.0 Family
PP
Table 6-14 Status of external pins during IDLE and Power Down modes
=11.5V±0.5V using five /PROG(ALE) pulses per byte programmed (typ. 100us).
Program
Memory
External
External
Internal
Internal
ALE
H
H
L
L
/PSEN
H
H
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L
L
Port 0
Float
Float
Data
Data
Port 1
Data
Data
Data
Data
Address
Port 2
Data
Data
Data
Port 3
Data
Data
Data
Data
Port 4
2
Data
Data
Data
Data
).