ATmega32A Datasheet - Sunrom Technologies

ATmega32A24.3.1 Bypass RegisterThe Bypass Register consists of a single Shift Register stage. When the Bypass Register isselected as path between TDI and TDO, the register is reset to 0 when leaving the Capture-DRcontroller state. The Bypass Register can be used to shorten the scan chain on a system whenthe other devices are to be tested.24.3.2 Device Identification RegisterFigure 24-1 shows the structure of the Device Identification Register.Figure 24-1.The Format of the Device Identification RegisterMSBLSBBit 31 28 27 12 11 1 0Device ID Version Part Number Manufacturer ID 14 bits 16 bits 11 bits 1 bit24.3.2.1 VersionVersion is a 4-bit number identifying the revision of the component. The JTAG version numberfollows the revision of the device. Revision A is 0x0, revision B is x1 and so on.24.3.2.2 Part NumberThe part number is a 16-bit code identifying the component. The JTAG Part Number forATmega32A is listed in Table 24-1.Table 24-1.AVR JTAG Part NumberPart NumberATmega32AJTAG Part Number (Hex)0x950224.3.2.3 Manufacturer IDThe Manufacturer ID is a 11 bit code identifying the manufacturer. The JTAG manufacturer IDfor ATMEL is listed in Table 24-2.Table 24-2.Manufacturer IDManufacturerATMELJTAG Man. ID (Hex)0x01F24.3.3 Reset RegisterThe Reset Register is a Test Data Register used to reset the part. Since the AVR tri-states PortPins when reset, the Reset Register can also replace the function of the unimplemented optionalJTAG instruction HIGHZ.A high value in the Reset Register corresponds to pulling the External Reset low. The part isreset as long as there is a high value present in the Reset Register. Depending on the Fuse settingsfor the clock options, the part will remain reset for a Reset Time-Out Period (refer to “ClockSources” on page 26) after releasing the Reset Register. The output from this Data Register isnot latched, so the reset will take place immediately, as shown in Figure 24-2.8155C–AVR–02/11235