47.7.3.8 Mode Fault Detection

The MCSPI has the capability to operate in multihost environment. Consequently, the NPCS0/NSS line must be monitored. If one of the hosts on the SPI bus is currently transmitting, the NPCS0/NSS line is low and the MCSPI must not transmit any data. A mode fault is detected when the MCSPI is programmed in Host mode and a low level is driven by an external host on the NPCS0/NSS signal. In multihost environment, NPCS0, MOSI, MISO and SPCK pins must be configured in open drain (through the PIO controller). When a mode fault is detected, the Mode Fault Error (MODF) bit in MCSPI_SR is set until MCSPI_SR is read and the MCSPI is automatically disabled until it is reenabled by setting the MCSPI_CR.SPIEN bit.

By default, the mode fault detection is enabled. The user can disable it by setting the Mode Fault Detection (MODFDIS) bit in MCSPI_MR.