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I would like to connect several boards to the microcontroller and send data to shift registers placed on the boards. I'm cascading all the shift registers for the data sending from the SPI. But I would like to latch the values individually as the output of the shift register to the board is time controlled and asynchronous to the other registers.

I found this schematic to connect the SPI to the shift register :

Example of SPI connection to 74*595 shift register IC

(Schematic source)

With this connection I'm latching the signal directly after the transmission.

Is it possible to just use the clock and the data out of the SPI to connect to the register and choose my own latch signal ? the CS will "exist" in the software but will not be connected to the shift​ register.

thanks

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Is it possible to just use the clock and the data out of the Spi to connect to the register and choose my own latch signal ?

yes.

but there is a software alternative to that: keep a ram of data output. change the right bits, shift the data out and latch them all. that's equivalent to having individual latches if your changes to limited to individual bytes / bits.

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  • \$\begingroup\$ Hi Danny, thank you for the response. I don't exactly understand what you mean with the software alternative. Could you clarify? thanks! \$\endgroup\$ – nesrine ghajati Mar 9 '17 at 13:48
  • \$\begingroup\$ Let's say that you have three registers outputting 0x55, 0x22 and 0x11. And you just wanted to hanger the middle one to 0x33 and latch it. Instead of individual latches, you write 0x55, 0x33 and 0x11 and latch all three registers. \$\endgroup\$ – dannyf Mar 9 '17 at 14:49

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