SPI Interface only one line for MOSI and MISO

Projects Networking, Protocols, and Devices
1

Hi guys.
I‘m currently using a display driver that communicates with SPI protocol, it only uses one line to communicate with the microcontroller.
I now have to add more I/O so I looked into using an mcp23s17.
I have used the I2C variant before but never the SPI one.
To minimize usage of my I/O I thought about using only one line for the MISO and MOSI line, so basically connecting them.
Is that possible?

2

The display driver is a stled616s, it communicates through only one line but can read and send data through that one line

3

Some STM32 has built-in support for half-duplex SPI on a single line

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If there is no hardware support, you can always create a software bit-bang driver.

4

Possible but will not actually work. In the same way as anything is possible in terms of wiring but only correct wiring will work.

For using multiple devices on the SPI the trick is to use a different pin on the enable pin for each device. You put that low for the one device you want to communicate with before you start and only that device will respond.