SLAU320AJ July 2010 – May 2021
The SBW interface serial communication uses time-division multiplexing and allocates three time slots: TMS_SLOT, TDI_SLOT, and TDO_SLOT. To clock TCLK through the SBW interface in a similar method as it is clocked through TDI during 4-wire JTAG access, an alternative JTAG timing method is implemented. This implementation makes use of the fact that the TDI and TMS signals are captured with the falling edge of SBWTCK in their respective slots as shown in Figure 2-8.
The logic that translates between the 2-wire and 4-wire interfaces is shown in Figure 2-9.
The advantages of this implementation are:
After power up, as long as the SBW interface is not activated yet, TMS and TDI are set to logic 1 level internally.