SED1354 Datasheet, PDF (382/472 Pages) Epson Company – Color Graphics LCD/CRT Controller

Page 12
Epson Research and Development
Vancouver Design Center
3.2 Generic MPU Host Bus Interface Signals
The interface requires the following signals:
• BUSCLK is a clock input which synchronizes transfers between the host CPU and the
SED1354. It is separate from the pixel 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.
• Chip Select (CS#) is driven by decoding the high-order address lines to select the proper
IO or memory address space.
• M/R# is driven high for memory accesses, or low for SED1354 register accesses. On
CPUs which implement memory-mapped IO, this pin is typically tied to an address line;
on CPUs with separate IO spaces, this pin is typically driven by control logic from the
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 SED1354.
• RD# and 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 SED1354.
• WAIT# is a signal which is output from the SED1354 to the host CPU which indicates
when data is ready (read cycle) or accepted (write cycle) on the host bus. Since host
CPU accesses to the SED1354 may occur asynchronously to the display update, it is
possible that contention may occur in access to the 1354 internal registers and/or refresh
memory. The WAIT# line resolves these contentions by forcing the host to wait until the
resource arbitration is complete. This signal is active low and needs to be inverted using
MD5 since the MCF5307 wait state signal is active high.
• The Bus Status (BS#) signal is unused in general purpose bus mode, and should be tied
high (connected to IO V_DD).
SED1354
X19A-G-011-06
Interfacing to the Motorola MCF5307 "Coldfire" Microprocessor
Issue Date: 99/12/23