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Preliminary Technical Data

ADE7566/ADE7569

Rev. PrA | Page 99 of 136

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. Once 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

implemented after downloading the program. The commands

used for this operation are an extension of the commands listed

in the Application Note uC004: Understanding the Serial

Download Protocol.

•

Command with ASCII code I or 0x49 write the data into R0.

•

Command with ASCII code F or 0x46 write R0 into the

SFR address defined in the data of this command.

By omitting the protocol defined in the uC004: Understanding

the Serial Download Protocol application note, the sequence to

load protections are 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:

•

Command I with data = value of protection byte 0x3FFF.

•

Command F with data = 0xC7.

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.

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 ADE7566/ADE7569

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.

Protection bits can be 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.

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 97.

Table 97.

Command

Bytes Affected

Flash Memory Timing

Write Byte

1 byte

30 μs

Erase Page

512 bytes

20 ms

Erase All

16 kB

200 ms

Read Byte

1 bytes

100 ns

Erase Page and

Write Byte

512 bytes

21 ms

Verify 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, 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 ADE7566/ADE7569 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. When in serial download

mode, the hidden embedded 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 ADE7566/ADE7569

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 configuration bits

cannot be programmed in serial download mode.

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