Epson Research and Development

Page 11

Vancouver Design Center

 

 

 

3.2 Generic MPU Host Bus Interface Signals

The interface requires the following signals:

BUSCLK is a clock input which is required by the S1D13504 host bus interface. It is separate from the input clock (CLKI) and is typically driven by the host CPU system clock.

The address inputs AB[20:0], and the data bus DB[15:0], connect directly to the CPU address and data bus, respectively. The hardware engineer must ensure that MD4 selects the proper endian mode upon reset.

M/R# (memory/register) may be considered an address line, allowing system address A21 to be connected to the M/R# line.

Chip Select (CS#) must be driven low whenever the S1D13504 is accessed by the host CPU.

WE0# and WE1# are write enables for the low-order and high-order bytes, respectively, to be driven low when the host CPU is writing data to the S1D13504. These signals must be generated by external hardware based on the control outputs from the host CPU.

RD# (RD0#) and RD/WR# (RD1#) are read enables for the low-order and high-order bytes, respectively, to be driven low when the host CPU is reading data from the S1D13504. These signals must be generated by external hardware based on the control outputs from the host CPU.

WAIT# is a signal output from the S1D13504 that indicates the host CPU must wait until data is ready (read cycle) or accepted (write cycle) on the host bus. Since host CPU accesses to the S1D13504 may occur asynchronously to the display update, it is possible that contention may occur in accessing the S1D13504 internal registers and/or display buffer. The WAIT# line resolves these contentions by forcing the host to wait until the resource arbitration is complete.

The Bus Start (BS#) signal is not used for the Generic MPU host bus interface and should be tied low (connected to GND).

Interfacing to the NEC VR4102™ Microprocessor

S1D13504

Issue Date: 01/02/02

X19A-G-007-07

Page 395
Image 395
Epson S1D13504 manual Generic MPU Host Bus Interface Signals