ATmega32(L)
Reset Register
The Reset Register is a Test Data Register used to reset the part during programming. It
is required to reset the part before entering programming mode.
A high value in the Reset Register corresponds to pulling the external Reset low. The
part is reset as long as there is a high value present in the Reset Register. Depending
on the Fuse settings for the clock options, the part will remain reset for a Reset Time-out
Period (refer to “Clock Sources” on page 25) after releasing the Reset Register. The
output from this Data Register is not latched, so the reset will take place immediately, as
shown in Figure 115 on page 227.
Programming Enable Register The Programming Enable Register is a 16-bit register. The contents of this register is
compared to the programming enable signature, binary code 1010_0011_0111_0000.
When the contents of the register is equal to the programming enable signature, pro-
gramming 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 139. Programming Enable Register
TDI
$A370
D
D
Q
A
T
A
Programming Enable
=
ClockDR & PROG_ENABLE
TDO
Programming Command
Register
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 116. The
state sequence when shifting in the programming commands is illustrated in Figure 141.
277
2503J–AVR–10/06
ATMEL [ ATMEL ]
