SN74HC595: SPI Address

Hi Brian,

The SN74HC595 does not communicate via SPI, but it is common to read and load shift registers via SPI.

The application note Designing with Shift Registers is an excellent resource about how shift registers work and how to incorporate them into designs, and it is applicable to SN74HC595. Section 2.5 Software Overview discusses software control of shift registers. Section 3.3 Software Examples shows an example using SPI to read and load a shift register.

Regards,

Nikki

SPI devices do not have addresses. When connecting multiple SPI slaves to an SPI master, you use separate /CS signals for them.

With the '595, you would typically connect the master's /CS signal to the RCLK pin so that the shifted-in value becomes visible at the outputs at the end of the SPI transmission. (This implies that all values sent to any slave over the SPI bus are read into the shift register, but without the RCLK edge, that does not have any visible effect.)