ADE5166 datasheet(105/148 Pages) AD

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ADE5166/ADE5169

Rev. 0 | Page 105 of 148

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 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 the 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 ADE5166/ADE5169

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 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 110.

Table 110. 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 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

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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