KS152JB Universal Communications Controller Technical Specifications
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( ) ;
4.5 Summary of DMA Control Bits
DCONs
DAS IDA
SAS
ISA
DM
TM
DONE
GO
DAS 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
GO is the enable bit for the DMA Channel itself. The DMA Channel is inactive if GO= 0.
Kawasaki LSI USA, Inc. | Page 91 of 120 | Ver. 0.9 KS152JB2 |