Cybersecurity and privacy risk assessment of point-of-care systems in healthcare: A use case approach
JTAG is an acronym for Joint Test Action Group and refers to the IEEE 1149.1 standard for Test Access Port and Boundary Scan. JTAG are specifications of a four-pin (plus power/ground) interface designed to test connections between chips. The interface is serial. The clock input is at the TCK pin. Configuration is performed by manipulating a state machine one bit at a time through a TMS pin. Then transferring one bit of data is transferred in and out per TCK clock pulse at the TDI and TDO pins, respectively. Different instruction modes can be loaded to read the chip ID, sample input pins, drive (or float) output pins, manipulate chip functions, or bypass (pipe TDI to TDO to logically shorten chains of multiple chips). The operating frequency varies depending on the chip, but it is typically 10-100MHz TCK (10-100ns per bit time). Note that storage (RAM, disc,etc.) is usually measured in binary thousands, i.e., 1,024 bits,K, Kb or Kilobits.