Maxim Integrated MAXQ Family Users Guide: MAXQ8913 Supplement - Manual (Page 54)

MAXQ Family User’s Guide:
MAXQ8913 Supplement
17-1
ADDENDUM TO SECTION 17: IN-SYSTEM PROGRAMMING (JTAG)
The MAXQ8913 provides a JTAG-compatible debug port interface for in-system programming (bootloader) operations.
In order to use this interface for in-system programming, the SPE bit must be set through the debug port. This is done
while the device is held in reset, using the system programming instruction as described in the MAXQ Family User’s
Guide.
17.1 JTAG Bootloader Protocol
The only bootloader interface supported for the MAXQ8913 is the debug port. When using the debug port, 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 com-
mand 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 character “>” (byte value 03Eh).
Bootloader commands that fail for any reason set the bootloader status byte to an error code value describing the
reason for the failure. This status byte can be read by means of the Get Status command (04h).
Table 17-1. Bootloader Status Codes
All commands in Family 0 can be executed without first matching the password. All other commands (in families 1x
through Fx) are password protected; the password must first be matched before these commands can be executed.
A special case exists when the program memory has not been initialized (following master erase). If the password
(stored in word locations 0010h to 001Fh in program memory) is all 0000h words or all FFFFh words, the bootloader
treats the password as having been matched and automatically unlocks the password bit. This allows access to
password-protected commands following master erase (when no password has been set in program memory).
When providing addresses for code or data read or write to bootloader commands, all addresses run from 0000h to
(memory size – 1).
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 Match Password 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.
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