Kawasaki 80C152 - Manual (Page 48)

KS152JB Universal Communications Controller
Technical Specifications
Kawasaki LSI USA, Inc. Page 48 of 120 Ver. 0.9 KS152JB2
interframe space and the preamble length such that the acknowledge is completed before IFS
expires. This is normally done by programming IFS larger than the preamble.
A transmitting station with HABEN enabled expects an acknowledge. It must receive one prior to
the end of the interframe space, or else an error is assumed and the NOACK bit is set. Setting of
the TDN bit is also delayed until the end of the interframe space. Collisions detected during the
interframe space will also cause NOACK to be set.
If the user software has enabled DMA servicing of the GSC, an interrupt is generated when TDN
is set. TDN will be set at the end of the interframe space if a hardware based acknowledge is
required and received. If the GSC is serviced by the CPU, the user must time out the interframe
space and then check TDN before disabling the transmitter or transmit error interrupts. NOACK
will generate a transmit error interrupt if the transmitter and interrupts are enabled during the
interframe space.