/*
 * This module encapsulates the application function of our board:
 * dual UART with 2.8V outputs.
 */

module application_block (GND, P_3V3, P_2V8, ADBUS, BDBUS);

input GND, P_3V3, P_2V8;

inout [7:0] ADBUS, BDBUS;

/* 2.8V output wires */

wire TxD_2V8_before_R, RTS_2V8_before_R, DTR_2V8_before_R, TxD2_2V8_before_R;
wire TxD_2V8_after_R, RTS_2V8_after_R, DTR_2V8_after_R, TxD2_2V8_after_R;

/* input signal wires */

wire RxD_in, CTS_in, DSR_in, DCD_in, RI_in, RxD2_in;

/* output buffers */

buffer_ic_common output_buf_common (.Vcc(P_2V8),
				    .GND(GND),
				    .nOE1(GND),
				    .nOE2(GND)
	);

capacitor output_buf_bypass_cap (P_2V8, GND);

buffer_ic_slot buf_TxD  (.A(ADBUS[0]), .Y(TxD_2V8_before_R));
buffer_ic_slot buf_RTS  (.A(ADBUS[2]), .Y(RTS_2V8_before_R));
buffer_ic_slot buf_DTR  (.A(ADBUS[4]), .Y(DTR_2V8_before_R));
buffer_ic_slot buf_TxD2 (.A(BDBUS[0]), .Y(TxD2_2V8_before_R));

buffer_ic_slot unused_output_buf1 (.A(GND), .Y());
buffer_ic_slot unused_output_buf2 (.A(GND), .Y());
buffer_ic_slot unused_output_buf3 (.A(GND), .Y());
buffer_ic_slot unused_output_buf4 (.A(GND), .Y());

/* output series resistors */

resistor TxD_series_R (TxD_2V8_before_R, TxD_2V8_after_R);
resistor RTS_series_R (RTS_2V8_before_R, RTS_2V8_after_R);
resistor DTR_series_R (DTR_2V8_before_R, DTR_2V8_after_R);
resistor TxD2_series_R (TxD2_2V8_before_R, TxD2_2V8_after_R);

/* input buffers */

buffer_ic_common input_buf_common (.Vcc(P_3V3),
				   .GND(GND),
				   .nOE1(GND),
				   .nOE2(GND)
	);

capacitor input_buf_bypass_cap (P_3V3, GND);

buffer_ic_slot buf_RxD  (.A(RxD_in),  .Y(ADBUS[1]));
buffer_ic_slot buf_CTS  (.A(CTS_in),  .Y(ADBUS[3]));
buffer_ic_slot buf_DSR  (.A(DSR_in),  .Y(ADBUS[5]));
buffer_ic_slot buf_DCD  (.A(DCD_in),  .Y(ADBUS[6]));
buffer_ic_slot buf_RI   (.A(RI_in),   .Y(ADBUS[7]));
buffer_ic_slot buf_RxD2 (.A(RxD2_in), .Y(BDBUS[1]));

buffer_ic_slot unused_input_buf1 (.A(GND), .Y());
buffer_ic_slot unused_input_buf2 (.A(GND), .Y());

/* input pull-up resistors */

resistor RxD_pullup (RxD_in, P_2V8);
resistor CTS_pullup (CTS_in, P_2V8);
resistor DSR_pullup (DSR_in, P_2V8);
resistor DCD_pullup (DCD_in, P_2V8);
resistor RI_pullup  (RI_in,  P_2V8);
resistor RxD2_pullup (RxD2_in, P_2V8);

/* target interface headers */

target_if target_if (	.GND(GND),
			.UART0_TxD(TxD_2V8_after_R),
			.UART0_RxD(RxD_in),
			.UART0_RTS(RTS_2V8_after_R),
			.UART0_CTS(CTS_in),
			.UART0_DTR(DTR_2V8_after_R),
			.UART0_DSR(DSR_in),
			.UART0_DCD(DCD_in),
			.UART0_RI(RI_in),
			.UART1_TxD(TxD2_2V8_after_R),
			.UART1_RxD(RxD2_in)
	);

endmodule