What is the timing relationship between TDI/SDIN and TDO/SDOUTBS?

TDI is fed into a D-type Flip Flop, clocked by the rising edge of TCK. The output of this Flip Flop is presented on SDIN. If one of the user added scan chains is selected, SDOUTBS is fed asynchronously through from the user added scan chain to TDO.

The same applies to the ARM7TDMI, only there SDIN in the above picture is called SDINBS. Data is clocked out of the ARM core and out of each scan chain element on the rising edge of TCK. Data is clocked into a scan chain element at the falling edge of TCK.

See also:

• App Note 28 The ARM7TDMI Debug Architecture (370KB) (DAI 0028A)
• How do I add scan chains to the ARM TAP controller?
• Is RTCK required as a dedicated output?