ADE7518ASTZF16-RL Analog Devices Inc, ADE7518ASTZF16-RL Datasheet - Page 80

• Manufacturer Part Number: ADE7518ASTZF16-RL
• Description: 1-Phase Energy Meter IC
• Manufacturer: Analog Devices Inc

Specifications of ADE7518ASTZF16-RL

• Applications: Energy Measurement
• Core Processor: 8052
• Program Memory Type: FLASH (16 kB)
• Controller Series: ADE75xx
• Ram Size: 512 x 8
• Interface: I²C, SPI, UART
• Number Of I /o: 20
• Voltage - Supply: 3.135 V ~ 3.465 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADE7518
Table 66. Watchdog and Flash Protection Byte in Flash (Flash Address = 0x3FFA)
Bit
7
6 to 0
Writing to the Watchdog Timer SFR (WDCON, 0xC0)
Writing data to the WDCON SFR involves a double instruction
sequence. The WDWR bit must be set and the following
instruction must be a write instruction to the WDCON SFR.
Disable Watch dog
CLR EA
SETB WDWR
CLR WDE
SETB EA
This sequence is necessary to protect the WDCON SFR from
code execution upsets that may unintentionally modify this
SFR. Interrupts should be disabled during this operation due to
the consecutive instruction cycles.
Mnemonic
WDPROT_PROTKY7
PROTKY[6:0]
Default
1
0xFF
Description
This bit holds the protection for the watchdog timer and the seventh bit of the flash protection key.
When this bit is cleared, the watchdog enable (WDE) and interrupt response bits (WDIR) cannot
be changed by user code. The watchdog configuration is then fixed to WDIR = 0 and WDE = 1.
The watchdog timeout in PRE[3:0] can still be modified by user code.
The value of this bit is also used to set the flash protection key. If this bit is cleared to protect the
watchdog, then the default value for the flash protection key is 0x7F instead of 0xFF (see the
Protecting the Flash Memory section for more information on how to clear this bit).
These bits hold the flash protection key. The content of this flash address is compared to the
Flash Protection Key SFR (PROTKY, 0xBB) when the protection is being set or changed. If the two
values match, the new protection is written to Flash Address 0x3FFF to Flash Address 0x3FFB.
See the Protecting the Flash Memory section for more information on how to configure these bits.
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Watchdog Timer Interrupt
If the watchdog timer is not cleared within the watchdog timeout
period, a system reset occurs unless the watchdog timer interrupt
is enabled. The watchdog timer interrupt enable bit (WDIR) is
located in the Watchdog Timer SFR (WDCON, 0xC0). Enabling
the WDIR bit allows the program to examine the stack or other
variables that may have led the program to execute inappropriate
code. The watchdog timer interrupt also allows the watchdog to
be used as a long interval timer.
Note that WDIR is automatically configured as a high priority
interrupt. This interrupt cannot be disabled by the EA bit in the
IE register (see Table 58). Even if all of the other interrupts are
disabled, the watchdog is kept active to watch over the program.