
II CORE BLOCK: BCU (Bus Control Unit)
B-II-4-2
EPSON
S1C33T01 FUNCTION PART
User interface signals
Table 4.2
List of User Interface Signals
Signal name
I/O
Cell
name
Function
U_ADDR [0]
O
XBF4
When address bus (A0)/SBUSST (D3/0x4812E) = "0" (default)
When the bus strobe (lower byte) signal (#BSH)/SBUSST (D3/0x4812E) = "1"
U_ADDR [23:1]
O
XBF4
Address bus (A1 to A23)
U_DOUT [15:0]
O
XBF4
Output data bus
This bus is used when the CPU writes data to user logic.
U_DIN [15:0]
I
XAO22V
Input data bus
This bus is used when the CPU reads from user logic.
U_CE10_X
U_CE9_X
U_CE8_X
U_CE7_X
U_CE6_X
U_CE5_X
U_CE4_X
O
XBF4
Areas 4 to 10 chip enable signals
These signals go lowwhen the CPU accesses the user logiccircuits allocated to areas4 through
10.
U_WRL_X
O
XBF4
When the write (lower byte) signal (#WRL)/SBUSST (D3/0x4812E) = "0" (default)
When the write signal (#WRL)/SBUSST (D3/0x4812E) = "1"
This signal goes low when the CPU writes the low-order 8 bits of data to the user logic.
U_WRH_X
O
XBF4
When the write (upper byte) signal (#WRH)/SBUSST (D3/0x4812E) = "0" (default)
When the bus strobe (upper byte) signal (#BSH)/SBUSST (D3/0x4812E) = "1"
This signal goes low when the CPU writes the high-order 8 bits of data to the user logic.
U_RD_X
O
XBF4
Read signal
This signal goes low when the CPU reads data from the user logic.
U_WAIT_X
I
XAO22V
Wait cycle request input
User logic can request wait cycles by setting this signal low.
U_P3_PIN [5:0]
U_P2_PIN [7:0]
U_P1_PIN [6:5]
U_P1_PIN [4:3]
U_P1_PIN [2]
U_P1_PIN [1:0]
U_P0_PIN [7:0]
U_K5_PIN [4:0]
O
XBF2
The port P 3x, 2x, 1x, and 0x signals, and the port K 5x signal
These signals report the values of the ports to the user logic.
U_BUSMD [2:0]
O
XBF2
Bus cycle test data signal
U_BUSSZ [1:0]
O
XBF2
Bus size signal
U_BCLK
O
XBF4
Bus clock
The user logic can use the bus clock (BCLK) signal.
U_OS1CLK
O
XBF4
Low-speed oscillator circuit (OSC1) output
This signal can be used as the user logic clock source.
U_OS3CLK
O
XBF4
High-speed oscillator circuit (OSC3) output
This signal can be used as the user logic clock source.
U_PLLCLK
O
XBF4
PLL circuit output
U_CPUCLK
O
XCRBF6
CTS clock
U_RST_X
O
XBF4
Reset signal
This signal reports the reset timing to the user logic.
TST_USER
O
XBF2
User circuit test mode
TST_TA
O
XBF16
I/O cell TA pin connection signal
TST_TE_X
O
XBF16
I/O cell TE pin connection signal
TST_TS
O
XBF16
I/O cell TS pin connection signal
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.