354
7679H–CAN–08/08
AT90CAN32/64/128
25.9.1.1
AVR_RESET (0xC)
The AVR specific public JTAG instruction for setting the AVR device in the Reset mode or taking
the device out from the Reset mode. The TAP controller is not reset by this instruction. The one
bit Reset Register is selected as data register. Note that the reset will be active as long as there
is a logic “one” in the Reset Chain. The output from this chain is not latched.
The active states are:
• Shift-DR: The Reset Register is shifted by the TCK input.
25.9.1.2
PROG_ENABLE (0x4)
The AVR specific public JTAG instruction for enabling programming via the JTAG port. The 16-
bit Programming Enable Register is selected as data register. The active states are the
following:
• Shift-DR: The programming enable signature is shifted into the data register.
• Update-DR: The programming enable signature is compared to the correct value, and
Programming mode is entered if the signature is valid.
25.9.1.3
PROG_COMMANDS (0x5)
The AVR specific public JTAG instruction for entering programming commands via the JTAG
port. The 15-bit Programming Command Register is selected as data register. The active states
are the following:
• Capture-DR: The result of the previous command is loaded into the data register.
• Shift-DR: The data register is shifted by the TCK input, shifting out the result of the previous
command and shifting in the new command.
• Update-DR: The programming command is applied to the Flash inputs
• Run-Test/Idle: One clock cycle is generated, executing the applied command (not always
required, see
25.9.1.4
PROG_PAGELOAD (0x6)
The AVR specific public JTAG instruction to directly load the Flash data page via the JTAG port.
An 8-bit Flash Data Byte Register is selected as the data register. This is physically the 8 LSBs
of the Programming Command Register. The active states are the following:
• Shift-DR: The Flash Data Byte Register is shifted by the TCK input.
• Update-DR: The content of the Flash Data Byte Register is copied into a temporary register.
A write sequence is initiated that within 11 TCK cycles loads the content of the temporary
register into the Flash page buffer. The AVR automatically alternates between writing the low
and the high byte for each new Update-DR state, starting with the low byte for the first
Update-DR encountered after entering the PROG_PAGELOAD command. The Program
Counter is pre-incremented before writing the low byte, except for the first written byte. This
ensures that the first data is written to the address set up by PROG_COMMANDS, and
loading the last location in the page buffer does not make the program counter increment into
the next page.
25.9.1.5
PROG_PAGEREAD (0x7)
The AVR specific public JTAG instruction to directly capture the Flash content via the JTAG port.
An 8-bit Flash Data Byte Register is selected as the data register. This is physically the 8 LSBs
of the Programming Command Register. The active states are the following:
