Editing Serial Peripheral Interface (section)

=== Valid communications ===
Some slave devices are designed to ignore any SPI communications in which the number of clock pulses is greater than specified. Others do not care, ignoring extra inputs and continuing to shift the same output bit. It is common for different devices to use SPI communications with different lengths, as, for example, when SPI is used to access an IC's [[scan chain]] by issuing a command word of one size (perhaps 32 bits) and then getting a response of a different size (perhaps 153 bits, one for each pin in that scan chain).