Assume a 32-bit write-only register resides in a black box module. As a silicon validation engineer, you have write access to the register through the 32-bit configuration bus, but you do not have read access. Instead, you know what is the bit-XOR value of all 32 bits from the black box. If there is a random bit of the register that has a stuck-at fault, how can you identify which bit has the fault?
The simplest approach is the linear search. In the 1st step, you can write 32’h0000_0001 to the register and get the bit-XOR value, and then write 32’h0000_0000 and get the bit-XOR value again. All possible read values are shown in the table below: