Rainbow Electronics DS3134 - Manual (Page 169)

DS3134
169 of 203
10.2 LOCAL BUS BRIDGE MODE CONTROL REGISTER DESCRIPTION
Register Name: LBBMC
Register Description: Local Bus Bridge Mode Control Register
Register Address:
0040h
Note: This register can only be accessed via the PCI Bus and hence only in the PCI Bridge Mode. In the
Configuration Mode, this register cannot be accessed. It will be set to all zeros upon a hardware reset
issued via the PRST* pin. It will not be affected by a software reset issued via the RST control bit in the
Master Reset and ID (MRID) register.
7 6 5 4 3 2 1 0
n/a LBW LRDY3 LRDY2 LRDY1 LRDY0 LARBE LCLKE
15 14 13 12 11 10 9 8
n/a n/a n/a n/a LAT3 LAT2 LAT1 LAT0
Note: Bits that are underlined are read only, all other bits are read-write; default value for all bits is 0.
Bit 0 / Local Bus Clock Enable (LCLKE).
0 = tri-state the LCLK output signal pin
1 = allow LCLK to appear at the pin
Bit 1 / Local Bus Arbitration Enable (LARBE). When enabled, the LHOLD(LBR*), LBGACK*, and
LHLDA(LBG*) signal pins are active and the proper arbitration handshake sequence must occur for a
proper bus transaction. When disabled, the LHOLD(LBR*), LBGACK* and LHLDA(LBG*) signal pins
are deactivated and bus arbitration on the Local Bus is not invoked. In addition, the Arbitration Timer is
enabled (see the description of the LAT0 to LAT3 bits) when LARBE is set to a one.
0 = Local Bus Arbitration is disabled
1 = Local Bus Arbitration is enabled
Bit 2 / Local Bus Ready Control Bit 0 (LRDY0). lsb
Bit 3 / Local Bus Ready Control Bit 1 (LRDY1).
Bit 4 / Local Bus Ready Control Bit 2 (LRDY2).
Bit 5 / Local Bus Ready Control Bit 3 (LRDY3). msb
These control bits determine the duration of the Local Bus transaction in the PCI Bridge Mode. The bus
transaction can either be control via the external LRDY* input signal or via a predetermined period of 1
to 11 LCLK periods.
0000 = use the LRDY* signal input pin to control the bus transaction
0001 = bus transaction is defined as 1 LCLK period
0010 = bus transaction is defined as 2 LCLK periods
0011 = bus transaction is defined as 3 LCLK periods
0100 = bus transaction is defined as 4 LCLK periods
0101 = bus transaction is defined as 5 LCLK periods
0110 = bus transaction is defined as 6 LCLK periods
0111 = bus transaction is defined as 7 LCLK periods
1000 = bus transaction is defined as 8 LCLK periods
1001 = bus transaction is defined as 9 LCLK periods
1010 = bus transaction is defined as 10 LCLK periods