Datasheet

ATmega32A
 2018 Microchip Technology Inc. Data Sheet Complete DS40002072A-page 225
25.3.1 Bypass Register
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 Regis-
ter can be used to shorten the scan chain on a system when the other devices are to be tested.
25.3.2 Device Identification Register
Figure 25-1 shows the structure of the Device Identification Register.
Figure 25-1. The Format of the Device Identification Register
25.3.2.1 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 x1 and so on.
25.3.2.2 Part Number
The part number is a 16-bit code identifying the component. The JTAG Part Number for ATmega32A is listed in
Table 25-1.
25.3.2.3 Manufacturer ID
The Manufacturer ID is a 11 bit code identifying the manufacturer. The JTAG manufacturer ID is listed in Table 25-
2.
25.3.3 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 32) 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 25-2.
MSB LSB
Bit 31 2827 1211 1 0
Device ID Version Part Number Manufacturer ID 1
4 bits 16 bits 11 bits 1 bit
Table 25-1. AVR JTAG Part Number
Part Number JTAG Part Number (Hex)
ATmega32A 0x9502
Table 25-2. Manufacturer ID
JTAG Manufacturer ID (Hex)
0x01F