MEGA128CAN Datasheet, PDF (345/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

AT90CAN128
Programming Enable Register
period (refer to “Clock Sources” on page 35) after releasing the Reset Register. The out-
put from this data register is not latched, so the reset will take place immediately, as
shown in Figure 144 on page 292.
The Programming Enable Register is a 16-bit register. The contents of this register is
compared to the programming enable signature, binary code
0b1010_0011_0111_0000. When the contents of the register is equal to the program-
ming enable signature, programming via the JTAG port is enabled. The register is reset
to 0 on Power-on Reset, and should always be reset when leaving Programming mode.
Figure 165. Programming Enable Register
TDI
Programming Command
Register
D
A
0xA370
=
T
A
D
Q
Programming Enable
ClockDR & PROG_ENABLE
TDO
The Programming Command Register is a 15-bit register. This register is used to seri-
ally shift in programming commands, and to serially shift out the result of the previous
command, if any. The JTAG Programming Instruction Set is shown in Table 136. The
state sequence when shifting in the programming commands is illustrated in Figure 167.
4250E–CAN–12/04
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