ATmega16 datasheet(223/315 Pages) ATMEL

223 / 315 page

223

ATmega16(L)

2466E–AVR–10/02

Bypass Register

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.

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 relevant version

number is shown in Table 86.

•Part Number

The part number is a 16-bit code identifying the component. The JTAG Part Number for

ATmega16 is listed in Table 87.

•Manufacturer ID

The Manufacturer ID is a 11 bit code identifying the manufacturer. The JTAG manufac-

turer ID for ATMEL is listed in Table 88.

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 settings for the clock options, the part will remain reset for a Reset Time-

Out Period (refer to “Clock Sources” on page 23) 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

271211

Device ID

Version

Part Number

Manufacturer ID

4 bits

16 bits

11 bits

1 bit

Table 86. JTAG Version Numbers

Version

JTAG Version Number (Hex)

ATmega16 revision G

0x6

ATmega16 revision H

0x6

Table 87. AVR JTAG Part Number

Part Number

JTAG Part Number (Hex)

ATmega16

0x9403

Table 88. Manufacturer ID

Manufacturer

JTAG Man. ID (Hex)

ATMEL

0x01F

ATMEGA16 Datasheet(PDF) 223 Page - ATMEL Corporation

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