KS152JB Universal Communications Controller
Technical Specifications
Kawasaki LSI USA, Inc. Page 91 of 120 Ver. 0.9 KS152JB2
4.5 Summary of DMA Control BitsDAS specifies the Destination Address Space. If DAS = 0, the destination is in External Data
Memory. If DAS = 1 and IDA = 0, the destination is a Special Function Register (SFR). If DAS =
1 and IDA = 1, the destination is in Internal Data RAM.
IDA (Increment Destination Address) If IDA= 1, the destination address is automatically incre-
mented after each byte transfer. If IDA = 0, It is not.
SAS specifies the Source Address Space. If SAS = 0, the source is in External Data Memory. If
SAS = 1 and ISA = 0, the source is an SFR. If SAS = 1 and ISA = 0, the source is an SFR. If SAS
= 1 and ISA = 1, the source is Internal Data RAM.
ISA (Increment Source Address) If ISA = 1, the source address is automatically incremented after
each byte transfer. If ISA = 0, it is not.
DM (Demand Mode) If DM = 1, the DMA Channel operates in Demand Mode. In Demand Mode
the DMA is initiated either by an external signal or by a Serial Port Flag, depending on the value
of the TM bit. If DM = 0, the DMA is requested by setting the GO bit in software.
TM (Transfer Mode) If DM = 1 then TM selects whether a DMA is initiated by an external signal
(TM = 1) or by a Serial Port flag (TM =0). If DM = 0 then TM selects whether the data transfers
are to be in bursts (TM = 1) or in alternate cycles (TM = 0).
DONE indicates the completion of a DMA operation and flags an interrupt. It is set to 1 by on-
chip hardware when BCRn = 0, and is cleared to 0 by on-chip hardware when the interrupt is vec-
tored to. It can also be set or cleared by software.
GO is the enable bit for the DMA Channel itself. The DMA Channel is inactive if GO= 0.
hold_holda ( ):
if (ARB = 0 .AND. REQ = 0) return 1;
if SARn = XRAM .OR. DARn =XRAM)
{
if (ARB =1 .AND. HLDA = 1) return 1;
if (REQ = 1 .AND. HLDA = 0) return 1;
else return 0 ;
}
return 1;
end hold_holda( ) ;
DAS IDA SAS ISA DM TM DONE GO
DCONs