atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 340

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

27.3.1
27.3.2
27.3.2.1
27.3.2.2
27.3.2.3
27.3.3
340
ATmega32U4
Bypass Register
Device Identification Register
Reset Register
Version
Part Number
Manufacturer ID
The Bypass Register consists of a single Shift Register stage. When the Bypass Register 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 27-1
Figure 27-1. 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
ATmega32U4 is listed in
Table 27-1.
The Manufacturer ID is a 11-bit code identifying the manufacturer. The JTAG manufacturer ID
for ATMEL is listed in
Table 27-2.
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
Sources” on page
not latched, so the reset will take place immediately, as shown in
Bit
Device ID
Part Number
AVR USB
Manufacturer
ATMEL
MSB
31
Version
4 bits
shows the structure of the Device Identification Register.
AVR JTAG Part Number
Manufacturer ID
27) after releasing the Reset Register. The output from this Data Register is
28
Table
27
Part Number
16 bits
Table
27-2.
27-1.
JTAG Manufacturer ID (Hex)
JTAG Part Number (Hex)
12
Manufacturer ID
11 bits
11
0x9782
0x01F
Figure
27-2.
1
LSB
1
1-bit
7766A–AVR–03/08
0
“Clock