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II CORE BLOCK: BCU (Bus Control Unit)
B-II-4-2 EPSON S1C33L03 FUNCTION PART
User interface signals
Table 4.2 List of User Interface Signals
Signal name I/O Function
Internal_addr0 O•Address bus (a0) when SBUSST(D3/0x4812E) = "0" (default)
•Bus strobe (low byte) signal (#BSL) when SBUSST(D3/0x4812E) = "1"
Internal_addr[23:1] OAddress bus (a1 to a23)
Internal_dout[15:0] OOutput data bus (dout0 to dout15)
This data bus is used when the CPU writes data to the on-chip user logic.
Internal_din[15:0] IInput data bus (din0 to din15)
This data bus is used when the CPU reads data from the on-chip user logic.
Internal_ce4_x
Internal_ce5_x
Internal_ce6_x
OAreas 6–4 chip enable signals
These signals go low when the CPU accesses the user logic circuits that are mapped to Areas 6–4.
Internal_rd_x ORead signal
This signal goes low when the CPU reads data from the user logic.
Internal_wrl_x O•Write (low byte) signal (#WRL) when SBUSST(D3/0x4812E) = "0" (default)
•Write signal (#WR) when SBUSST(D3/0x4812E) = "1"
This signal goes low when the CPU write 8 low-order bit data to the user logic.
Internal_wrh_x O•Write (high byte) signal (#WRH) when SBUSST(D3/0x4812E) = "0" (default)
•Bus strobe (high byte) signal (#BSH) when SBUSST(D3/0x4812E) = "1"
This signal goes low when the CPU write 8 high-order bit data to the user logic.
Internal_osc3_clk OHigh-speed (OSC3) oscillation clock output
This can be used as a source clock for the user logic.
Internal_pll_clk OPLL output clock
This can be used as a source clock for the user logic.
Internal_wait_x IWait cycle request input
The user logic can request to insert wait cycles by setting this signal to low.
Internal_irrd_x OInstruction fetch indicator signal
This signal goes low when the CPU is in an instruction fetch cycle.
Internal_k60-k67 IInput signals
These signals are connected to the input ports K60–K67. The user logic can request HSDMA, IDMA and
interrupts using these signals. The user logic can also be used as input ports with these signals.
The internal bus signals are available when an internal access area is set using the BCU register.
The bus conditions can be programmed using the BCU registers similar to the external bus.