ade7518 Analog Devices, Inc., ade7518 Datasheet - Page 92

• Manufacturer Part Number: ade7518
• Description: Single-phase Energy Measurement Ic With 8052 Mcu, Rtc, And Lcd Driver
• Manufacturer: Analog Devices, Inc.

ADE7518
Enabling Flash Protection by Emulator Commands
Another way to set the flash protection bytes is to use some
reserved emulator commands available only in download mode.
These commands write directly to the SFRs and can be used to
duplicate the operation mentioned in the Enabling Flash Protection
by Code section. When these flash bytes are written, the part
can exit emulation mode by a reset and the protections are
effective. This method can be used in production and imple-
mented after downloading the program. The commands used
for this operation are an extension of the commands listed in
Application Note uC004, Understanding the Serial Download
Protocol, available at www.analog.com.
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By omitting the protocol defined in Application Note uC004,
Understanding the Serial Download Protocol, the sequence to
load protections is similar to the sequence presented in the
Enabling Flash Protection by Code section, except that two
emulator commands are necessary to replace one assembly
command. For example, to write the protection value in
EADRH, the two following commands need to be executed:
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Notes on Flash Protection
The flash protection scheme is disabled by default so that none
of the pages of the flash are protected from reading or writing/
erasing.
The last page must be read and write/erase protected for the
protection scheme to work.
To activate the protection settings, the ADE7518 must be reset
after configuring the protection.
After configuring protection on the last page and resetting the
part, protections that have been enabled can only be removed by
mass erasing the flash memory. The protection bits are read and
erase protected by enabling read and write/erase protection on the
last page, but the protection bits are never truly write protected.
Following this protocol, the protection can be written to the
flash using the same sequence as mentioned in the Enabling
Flash Protection by Code section. When the part is reset, the
protection is effective.
Command with ASCII Code I or 0x49 writes the data into R0.
Command with ASCII Code F or 0x46 writes R0 into the
SFR address defined in the data of this command.
Command I with data = value of Protection Byte 0x3FFF.
Command F with data = 0xC7.
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Protection bits can be modified from 1 to 0, even after the last
page has been protected. In this way, more protection can be
added but none can be removed.
The protection scheme is intended to protect the end system. Pro-
tection should be disabled while developing and emulating code.
Flash Memory Timing
Typical program and erase times for the flash memory are
shown in Table 90.
Table 90. Flash Memory Program and Erase Times
Command
Write Byte
Erase Page
Erase All
Read Byte
Erase Page and Write Byte
Verify Byte
Note that the core microcontroller operation is idled until the
requested flash memory operation is complete. In practice, this
means that even though the flash operation is typically initiated
with a two-machine-cycle MOV instruction to write to the
Flash Control SFR (ECON, 0xB9), the next instruction is not
executed until the Flash/EE operation is complete. This means
that the core cannot respond to interrupt requests until the
Flash/EE operation is complete, although the core peripheral
functions, such as counters and timers, continue to count as
configured throughout this period.
IN-CIRCUIT PROGRAMMING
Serial Downloading
The ADE7518 facilitates code download via the standard UART
serial port. The parts enter serial download mode after a reset or
a power cycle if the SDEN pin is pulled low through an external
1 kΩ resistor. When in serial download mode, the hidden embed-
ded download kernel executes. This allows the user to download
code to the full 16 kB of flash memory while the device is in-circuit
in its target application hardware.
Protection configured in the last page of the ADE7518 affects
whether flash memory can be accessed in serial download mode.
Read protected pages cannot be read. Write/erase protected pages
cannot be written or erased.
Bytes
Affected
1 byte
512 bytes
16 kB
1 byte
512 bytes
1 byte
Flash Memory
Timing
30 μs
20 ms
200 ms
100 ns
21 ms
100 ns