Datasheet
229
2466T–AVR–07/10
ATmega16(L)
controller state. The Bypass Register can be used to shorten the scan chain on a system when
the other devices are to be tested.
Device Identification
Register
Figure 114 shows the structure of the Device Identification Register.
Figure 114. The Format of the Device Identification Register
Version Version is a 4-bit number identifying the revision of the component. The JTAG version number
follows the revision of the device. Revision A is 0x0, revision B is 0x1 and so on. However, some
revisions deviate from this rule, and the relevant version number is shown in Table 87.
Part Number The part number is a 16-bit code identifying the component. The JTAG Part Number for
ATmega16 is listed in Table 88.
Manufacturer ID The Manufacturer ID is a 11 bit code identifying the manufacturer. The JTAG manufacturer ID
for ATMEL is listed in Table 89.
Reset Register The Reset Register is a Test Data Register used to reset the part. Since the AVR tri-states Port
Pins when reset, the Reset Register can also replace the function of the unimplemented optional
JTAG instruction HIGHZ.
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 set-
tings 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.
MSB LSB
Bit 3128271211 1 0
Device ID Version Part Number Manufacturer ID 1
4 bits 16 bits 11 bits 1 bit
Table 87. JTAG Version Numbers
Version JTAG Version Number (Hex)
ATmega16 revision G 0x6
ATmega16 revision H 0xE
ATmega16 revision I 0x8
ATmega16 revision J 0x9
ATmega16 revision K 0xA
ATmega16 revision L 0xB
Table 88. AVR JTAG Part Number
Part Number JTAG Part Number (Hex)
ATmega16 0x9403
Table 89. Manufacturer ID
Manufacturer JTAG Manufacturer ID (Hex)
ATMEL 0x01F