APB

PSTRB is a write strobe, allowing the requester to update only some bytes of the PWDATA bus.

For read transfers the requester knows which bytes it wants to read, so can ignore/mask any additional bytes returned on PRDATA, and so no need for a strobe signal which would just be unnecessary complication for read transfers.

PSTRB is a write strobe, allowing the requester to update only some bytes of the PWDATA bus.

For read transfers the requester knows which bytes it wants to read, so can ignore/mask any additional bytes returned on PRDATA, and so no need for a strobe signal which would just be unnecessary complication for read transfers.