| SPI Disadvantages Requires more pins on IC packages than PC, even in the three-wire variant
 No in-band addressing; out-of-band chip select signals are required on shared buses
 No hardware flow control by the slave
 No hardware slave acknowledgment
 Typically supports only one master device
 No error-checking protocol is defined
 Only handles short distances compared to RS-232, RS-485, or Can-bus
 Many existing variations
 
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