1 entering a password -6, 5 jtag bootloader protocol -6, Table 12-3. bootloader status codes -6 – Maxim Integrated MAXQ7666 User Manual
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12.4.1 Entering a Password
A password can be entered via the TAP interface directly by issuing the unlock-password debug-mode command. The unlock-password
command requires 32 follow-on transfer cycles, each containing a byte value to be compared with the program memory password.
12.5 JTAG Bootloader Protocol
When communicating with the bootloader using the JTAG interface, the clock rate (TCK) must be kept below 1/8 the system clock rate.
All bootloader commands begin with a single command byte. The high four bits of this command byte define the command family (from 0
to 15), while the low four bits define the specific command within that family. All commands (except for those in Family 0) follow this format:
After each command has completed, the loader outputs a “prompt” byte to indicate that it has finished the operation. The prompt byte
is the single chararacter “>”.
Bootloader commands that fail for any reason set the bootloader status byte to an error code value describing the reason for the fail-
ure. See Table 12-3. This status byte can be read by means of the Get Status command (04h).
MAXQ7665/MAXQ7666 User’s Guide
12-6
BYTE 1
BYTE 2
BYTE 3
BYTE 4
(LENGTH) BYTES/WORDS
Command
Length
Param 1
Param 2
Data
STATUS VALUE
FUNCTION
00
No Error. The last command completed successfully.
01
Family Not Supported. An attempt was made to use a command from a family the bootloader does not support.
02
Invalid Command. An attempt was made to use a nonexistent command within a supported command family.
03
No Password Match. An attempt was made to use a password-protected command without first matching a valid password.
Or, the Password Match command was called with an incorrect password value.
04
Bad Parameter. The parameter (address or otherwise) passed to the command was out of range or otherwise invalid.
05
Verify Failed. The verification step failed on a Load/Verify or Verify command.
06
Unknown Register. An attempt was made to read from or write to a nonexistent register.
07
Word Mode Not Supported. An attempt was made to set word mode access, but the bootloader supports byte mode access
only.
08
Master Erase Failed. The bootloader was unable to perform master erase.
Table 12-3. Bootloader Status Codes
Maxim Integrated