AN4365, Qorivva MPC56xx Flash Programming Through Nexus/JTAG

1.2 TAP controller state machine
The TAP controller state machine controls the JTAG logic. The TAP controller state machine is a 16-state
finite state machine (FSM) as shown in Figure 1. The TCK and TMS signals control transition between
states of the FSM. These two signals control whether an instruction register scan or data register scan is
performed. Both the TDI and TMS inputs are sampled on the rising edge of TCK while the TDO output
changes on the falling edge of TCK. The value shown next to each state of the state machine in Figure 1
is the value of TMS required on the rising edge of TCK to transition to the connected state. Five rising
edges of TCK with TMS at logic 1 guarantees entry into the TEST LOGIC RESET state.
Qorivva MPC56xx Flash Programming Through Nexus/JTAG, Rev. 0
JTAG
Freescale Semiconductor 3