DS2703K Maxim Integrated, DS2703K Datasheet - Page 6

• Manufacturer Part Number: DS2703K
• Description: Battery Management
• Manufacturer: Maxim Integrated
• Series: DS2703r

DS2703EVKIT
MAIN PROGRAM WINDOW
All functions of the program are located in Main Program Window. These functions of the DS2703 are
divided into three sections: SHA-1 Commands, 1 Wire Commands, and Other Commands.
SHA-1 COMMANDS
The DS2703 uses an 8 byte Secret, the 8 byte ROM ID code of the device and an 8 byte Challenge to
generate a 20 byte Message Digest (also called the MAC) using the SHA-1 encryption algorithm.
The Secret
The user is able to update the 8 bytes of the Secret by entering the new Secret into the 8 text boxes below
the Secret label. The top-right text box is the LSB of the Secret, and the bottom-left text box is the MSB
of the Secret. (All text boxes are displayed in this same format.) With the desired Secret in place, left-
click on the Load Secret button.
This will write the new Secret to the DS2703 and provide a
programming pulse to store the Secret to the device.
The user can also permanently lock the Secret by left-clicking on the Lock Secret button. Once the Secret
is locked, it cannot be changed and cannot be read from the DS2703. The software will prompt the user
to make sure the Secret is ready to be permanently locked.
Another feature of the DS2703 is to generate the Next Secret from the existing Secret, ROM ID and
Challenge. It is important to Write the Challenge (see below) before left-clicking the Compute Next
Secret or Compute Next Secret with ID button. The device will perform the SHA-1 calculation and
create the Next Secret. The software will perform a SHA-1 calculation based on the values in the text
boxes for the Secret, ROM ID (if desired) and Challenge and place the new Secret, as calculated by
software, in the Secret text boxes. The new Secret is never read back from the device.
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