2 SPI Configurations sharing MOSI & MISO

[Milad]

Hello There, I want to connect two slaves to my nRF51422 PCA10028. I came up with the idea of using two master communications which share MOSI AND MISO but have different clocks and chip selects. I want to make sure that I can share the MISO and MOSI. Meanwhile, Is it another hard ware configuration for RX and TX buffers on different pins or that the only ones are 28 and 25?

Thank You

switch (spi_master_instance)
    {
        
        case SPI_MASTER_0:
        {
            spi_config.SPI_Pin_SCK  = 29;
            spi_config.SPI_Pin_MISO = 28;
            spi_config.SPI_Pin_MOSI = 25;
            spi_config.SPI_Pin_SS   = 24;
        }
        break;
				
			  case SPI_MASTER_1:
        {
            spi_config.SPI_Pin_SCK  = 27;
            spi_config.SPI_Pin_MISO = 28;
            spi_config.SPI_Pin_MOSI = 25;
            spi_config.SPI_Pin_SS   = 23;
        }
        break;
        

        default:
            break;
    }

[Hung Bui]

@Milad: I don't really understand why you want to have 2 masters. You can have one master and several slave. Just have to use the SS (Slave Select) pins to control which one should be active. It's described in this figure.

You can use any GPIO pin as MOSI, MISO etc.

[Hung Bui]

@Milad: Still I don't understand why you need 2 SPI master instance ?

You only need 2 SPI master when you need to have 2 slave working at the same time.

If they can take turn you can use just one master and use the SS pin to control them.

If you need to use 2 masters instance, and they work at the same time, you can't share any pin between them.