
22.12.1.3
Password setting, cancellation and authentication
·
Password setting
Because a password is created by using part of a user program, a special password setting routine
is unnecessary. A password can be set by simply writing a program to flash memory.
·
Password cancellation
To cancel a password, Chip Erase (all erase) must be performed on flash memory. A password
is canceled when flash memory is all initialized to 0xFF.
·
Password authentication
If there is data other than 0xFF in any one byte of data written to the address 0xFFE0 through
0xFFFF of the TMP89FM42, a product is considered a non-blank product, and password authen-
tication is required to execute an operation command. In this password authentication process,
PNSA, PCSA and a password string are used. An operation command is executed only if a pass-
word has been successfully authenticated. If a password is unsuccessfully authenticated, the
TMP89FM42 goes into an idle state.
If all data written to the address 0xFFE0 through 0xFFFF are 0xFF, a product is considered
blank, and no password authentication is performed. To execute some special operation com-
mands, however, PNSA and PCSA are still required (a password string is not required) even if a
product is blank. In this case, the addresses defined in
Table 22-21 must be selected as PNSA and
PCSA.
Whether a product is blank or non-blank can be confirmed by executing the status output com-
mand.
The operation commands that require PNSA and PCSA (password string) for them to be exe-
cuted are as follows:
-
Flash memory erase command (0xF0)
-
Flash memory write command (0x30)
-
Flash memory read command (0x40)
-
RAM loader command (0x60)
-
Flash memory security setting command (0xFA)
22.12.1.4
Password values and setting range
A password must be set in accordance with the conditions shown in
Table 22-21. If a password created
without meeting these conditions is used, a password error occurs. In this case, the TMP89FM42 does not
transmit data and goes into an idle state.
Table 22-21 Password Values and Setting Range
Password
Blank product (note 1)
Non-blank product
PNSA
(password count storage address)
0x8000 ≤ PNSA ≤ 0xFEFF
PCSA
(password comparison start ad-
dress)
0x8000 ≤ PCSA ≤ 0xFEFF
0x8000 ≤ PCSA ≤ 0xFF00 - N
N
(password count)
*
8 ≤ N
Password string
Not required (notes 4 and 5)
Required (note 3)
Note 1: *: Don’t care.
Note 2: When addresses from 0xFFE0 through 0xFFFF are filled with "0xFF", the product is recognized as a blank product.
TMP89FM42
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