relay with spi interface

[kunal123]

hi everyone,
i want to interface more than one relay to micrcontroller with spi interface, please help me how i can do this?

thanks & regards

 

[barry]

Could you ask a more specific question? Or do you just want us to do ALL your work for you.

 

[alexan_e]

I suppose he wants to control multiple relays using SPI so one solution is using a 74HC595 and then use the outputs to drive transistors (or a ULN2003) that drive the relays.
The 74HC595 can work either with normal pins or the SPI peripheral of the mcu.

 

[kunal123]

hi alexan_e,
if i want to control 256 relay & also want to read status of relay, then how i can do this.

thanks & regards

I suppose he wants to control multiple relays using SPI so one solution is using a 74HC595 and then use the outputs to drive transistors (or a ULN2003) that drive the relays.
The 74HC595 can work either with normal pins or the SPI peripheral of the mcu.

 

[alexan_e]

How do you mean the status read?
Since all the commands are given by the mcu you can keep the last status in a variable and read from there when you need to read the status.

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To control multiple replays you can use a few port expanders controlled by SPI like MCP23S17 **broken link removed** ans the appropritae driver for each relay