Device identification. To distinguish the ARM1156T2-S processor from other processors, the DBGTAP controller ID is unique for each. This means that a DBGTAP debugger such as RealView ICE can easily see which processor it is connected to. The Device ID register version and manufacturer ID fields are routed to the edge of the chip so that partners can create their own Device ID numbers by tying the pins to HIGH or LOW values. The default manufacturer ID for the ARM1156T2-S processor is b11110000111. The part number field is hard-wired inside the ARM1156T2-S to 0x7B56. All ARM semiconductor partner-specific devices must be identified by manufacturer ID numbers of the form shown in c0, Main ID Register.

32 bits.

When the ID code instruction is current, the shift section of the device ID register is selected as the serial path between DBGTDI and DBGTDO. There is no parallel output from the ID register. The 32-bit device ID code is loaded into this shift section during the Capture-DR state. This is shifted out during Shift-DR (least significant bit first) while a don’t care value is shifted in. The shifted-in data is ignored in the Update-DR state.

The order of bits in the ID code register is shown in Figure 14.4.