57.9.4.2.1 TWI as Host Only

In this mode, the TWI is considered as a host only (MSEN is always at one) and must be driven like a host with the ARBLST (ARBitration Lost) flag in addition.

If arbitration is lost (ARBLST = 1), the user must reinitiate the data transfer.

If the user starts a transfer (ex.: DADR + START + W + Write in THR) and if the bus is busy, the TWI automatically waits for a STOP condition on the bus to initiate the transfer (see figure "User Sends Data While the Bus is Busy" below).