Datasheet

Data Sheet ADE5166/ADE5169/ADE5566/ADE5569
Rev. D | Page 113 of 156
Enabling Flash Protection by Emulator Commands
Another way to set the flash protection bytes is to use the reserved
emulator commands available only in download mode. These
commands write directly to the SFRs and can be used to duplicate
the operation described in the Enabling Flash Protection by Code
section. When these flash bytes are written, the part can exit
emulation mode by reset and the protections are effective. This
method can be used in production and implemented after
downloading the program. The commands used for this opera-
tion are an extension of the commands listed in Application
Note AN-1074, Understanding the Serial Download Protocol,
available at www.analog.com.
• 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.
Omitting the protocol defined in the uC004 Application Note,
the sequence to load protections is similar to the sequence men-
tioned 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 the
EADRH SFR (Address 0xC7), the following two commands must
be executed:
• Command I with data = value of Protection Byte 0x3FFF
• Command F with data = 0xC7
With this protocol, the protection can be written to the flash
memory using the same sequence described in the Enabling
Flash Protection by Code section. When the part is reset, the
protection is effective.
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 write-/erase-protected for the protection
scheme to work.
To activate the protection settings, the ADE5166/ADE5169/
ADE5566/ADE5569 must be reset after configuring the pro-
tection.
After configuring protection on the last page and resetting the
part, protections that have been enabled can be removed only
by mass erasing the flash memory. The protection bits are never
truly write protected. Protection bits can be program modified
from a 1 to a 0, even after the last page has been protected. In
this way, more protection can be added, but none can be removed.
When the last page is read protected, the protection bits can still
be read by the user code. All other bits on this page are not
available for reading.
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 111.
Table 111. Flash Memory Program and Erase Times
Command Bytes Affected Flash Memory Timing
Write Byte 1 byte 30 µs
Erase Page 512 bytes 20 ms
Erase All
62 kB
2.5 sec
Read Byte 1 byte 100 ns
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, Address 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/timers continue to count, as configured, through-
out this period.
IN-CIRCUIT PROGRAMMING
Serial Downloading
The ADE5166/ADE5169/ADE5566/ADE5569 facilitate 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. Once in
serial download mode, the hidden embedded download kernel
executes. This allows the user to download code to the full 62 kB
of flash memory while the device is in circuit in its target
application hardware.
Protection configured in the last page of the ADE5166/ADE5169/
ADE5566/ADE5569 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. The con-
figuration bits cannot be programmed in serial download mode.