ADE7166_15 datasheet(114/152 Pages) AD

114 / 152 page

ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/ADE7569

Rev. B | Page 114 of 1

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 operation are an extension of the commands listed

in Application Note uC004, 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 uC004, the sequence to load

protections is similar to the sequence mentioned 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 (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 as 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 ADE7116/ADE7156/

ADE7166/ADE7169/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 be removed only

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.

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

16 kB

200 ms

Read Byte

1 byte

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, 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 counter/timers, continue to count, as

configured throughout this period.

IN-CIRCUIT PROGRAMMING

Serial Downloading

The ADE7116/ADE7156/ADE7166/ADE7169/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. Once 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 ADE7116/ADE7156/

ADE7166/ADE7169/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.

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