SLAU320AJ July 2010 – May 2021
This instruction enables setting of the MAB to a specific value, which is shifted in with the next JTAG 16-bit data access using the DR_SHIFT16 (16-bit Data) macro or the next JTAG 20-bit address word access using the DR_SHIFT (20-bit Address) macro. The MAB of the MSP430 CPU is set to the value written to the JTAG MAB register. The previous value stored in the JTAG MAB register is simultaneously shifted out on TDO while the new 16- or 20-bit address is shifted in through TDI.
In MSP430X devices, a 16-bit shift to update the JTAG MAB register does not automatically reset the upper four bits (19:16) of the JTAG MAB register. Always use the 20-bit shift macro to ensure that the upper four bits (19:16) are set to a defined value.