ATMEGA169 ATMEL [ATMEL Corporation], ATMEGA169 Datasheet - Page 233

• Manufacturer Part Number: ATMEGA169
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Bypass Register
Device Identification Register
Version
Part Number
Manufacturer ID
Reset Register
2514P–AVR–07/06
The Bypass Register consists of a single Shift Register stage. When the Bypass Regis-
ter is selected as path between TDI and TDO, the register is reset to 0 when leaving the
Capture-DR controller state. The Bypass Register can be used to shorten the scan
chain on a system when the other devices are to be tested.
Figure 107 shows the structure of the Device Identification Register.
Figure 107. The Format of the Device Identification Register
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.
The part number is a 16-bit code identifying the component. The JTAG Part Number for
ATmega169 is listed in Table 101.
Table 101. AVR JTAG Part Number
The Manufacturer ID is a 11-bit code identifying the manufacturer. The JTAG manufac-
turer ID for ATMEL is listed in Table 102.
Table 102. Manufacturer ID
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 settings for the clock options, the part will remain reset for a reset time-out
period (refer to “Clock Sources” on page 24) 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 108.
Bit
Device ID
Part Number
ATmega169
Manufacturer
ATMEL
MSB
31
Version
4 bits
28
27
Part Number
16 bits
JTAG Manufactor ID (Hex)
JTAG Part Number (Hex)
12
11
0x9405
Manufacturer ID
0x01F
ATmega169/V
11 bits
1
LSB
1-bit
1
0
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