Rainbow Electronics ATmega64L - Manual (Page 273)

273
ATmega16(L)
2466B–09/01
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 140. Programming Enable Register
Programming Command
Register The Programming Command register is a 15-bit register. This register is used to serially
shift in programming commands, and to serially shift out the result of the previous com-
mand, if any. The JTAG Programming Instruction Set is shown in Table 118. The state
sequence when shifting in the programming commands is illustrated in Figure 142.
Figure 141. Programming Command Register
TDI
TDO
D
A
T
A
=
D Q
ClockDR & PROG_ENABLE
Programming enable
$A370
TDI
TDO
S
T
R
O
B
E
S
A
D
D
R
E
S
S
/
D
A
T
A
Flash
EEPROM
Fuses
Lock Bits