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154 OpenSPISlave Type Subroutine Invocation OpenSPISlave(flags) Parameter Method Type Description flags ByVal Byte Flags controlling the SPI communication. Discussion This subroutine, available only for native mode devices, immediately activates the SPI interface in slave mode. The flags parameter specifies the characteristics of the SPI communication. They must be set to be compatible with the SPI master with which you want to communicate. See the table below for details. SPI Slave Mode Configuration Bits Function Hex Value Bit Mask Clock Phase False &H00 xx xx x0 xx Clock Phase True &H04 xx xx x1 xx Clock Low at Idle &H00 xx xx 0x xx Clock High at Idle &H08 xx xx 1x xx Bit Order – MSB first &H00 xx 0x xx xx Bit Order – LSB first &H20 xx 1x xx xx The chip select pin for an SPI slave is a dedicated pin; see the table below. If you activate slave mode, you must also provide an interrupt handler for the SPI_STC vector. While slave mode is active, SPICmd() calls are ineffective. Slave mode can be canceled by calling CloseSPI(). Slave Mode CS Pin ZX Models CS Pin ZX-40n 5, B.4 ZX-44n 44, B.4 ZX-24ne 24, B.4 ZX-1281n 10, B.0 ZX-1280n 19, B.0 ZX-128ne, ZX-1281ne 28, B.0 Note that the SPI master sets the SPI clock speed. The highest SPI clock speed that can be used reliably is one quarter of the CPU clock speed of a ZX slave device. Depending on how much computation the slave must perform to prepare data for sending back to the master, a substantially slower SPI clock may need to be used. If a ZX device is being used as the master, it may be useful to set the rxDelay parameter on calls to OpenSPI() on the master to allow additional processing time. Compatibility This subroutine is only supported for native mode devices. See Also CloseSPI, OpenSPI