Could anyone tell what is the advantages/disadavantages of using half duplex SPI over full duplex SPI communication. I know using half duplex, we can save one pin. But is this the only advantage of using half duplex? Is the rate at which master reads the data from the slave same for both mode of communication? Please reply
Regards
Half duplex unidirectional or write only mode could be used when master don't need data from slave. For example when working with most LCD it is usually OK to do writes only (although by reading status, framebuffer etc master can detect misbehavior and reset the slave, but LCD is usually not critical component and scheduled blind resets might be enough). The advantage is, as you mentioned, saving 1 pin.
Read/write clock rates are always same, since it is done simultaneously. MCUs SPI read and write buffers are shift registers with same clock, so when master is writing it is also reading (even if slave is not sending, in that case HIGH bits are received).
Mostly its a method for allowing a simpler design that has fewer pins on the CPU and allows for lower signal count on cables. Effectively you're trading speed and complexity for cost and simplicity.
