39.2.2 Data Registers
Once an instruction is shifted in and updated into the Instruction register,
the TAP controller places certain data registers between the TDI and TDO pins.
Additional data values can then be shifted into these data registers as needed. The PIC18-Q83 device family supports two data
registers:
- Bypass register: A single-bit
register which allows the boundary scan test data to pass through the selected
device to adjacent devices. The Bypass register is placed between the TDI and
TDO pins when the
BYPASSinstruction is active. - Device ID Register: A 32-bit part
identifier. It consists of an 11-bit manufacturer ID assigned by the IEEE (29h
for Microchip Technology), device part number and device revision identifier.
When the
IDCODEinstruction is active, the Device ID register is placed between the TDI and TDO pins. The device data ID is then shifted out onto the TDO pin, on the next 32 falling edges of TCK, after the TAP controller is in the Shift-DR.