view venus/src/usb/usb_core.v @ 36:c1256c8757c3

eliminate R209 and tie Iota VLMEM directly to UPR We already eliminated R210 (VLMEM pull-down option) earlier, because our simplified LCD power supply and reset line wiring is incompatible with 1.8V MEMIF. But with VLMEM always needing to be high, a pull-up resistor offers no advantage over a direct tie to UPR, so let's eliminate the superfluous resistor.
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 22 Nov 2021 19:19:59 +0000
parents 4722b265cb8c
children
line wrap: on
line source

/*
 * This module encapsulates the USB connector, the FT2232D block and
 * the glue components between them.
 */

module usb_core (GND, VBUS, P_5V, VCCIOA, VCCIOB,
		 ADBUS, ACBUS, SI_WUA, BDBUS, BCBUS, SI_WUB, PWREN);

input GND;
output VBUS, P_5V;

input VCCIOA, VCCIOB;
inout [7:0] ADBUS, BDBUS;
inout [3:0] ACBUS, BCBUS;
input SI_WUA, SI_WUB;
output PWREN;

/* interconnecting wires */

wire DM_connector_side, DM_chip_side;
wire DP_connector_side, DP_chip_side;
wire RSTOUT;

usb_conn conn  (.GND(GND),
		.VBUS(VBUS),
		.Dminus(DM_connector_side),
		.Dplus(DP_connector_side),
		.ID()	/* no connect */
	);

/* ferrite bead on the power supply */

inductor VBUS_ferrite (VBUS, P_5V);

/* series resistors on USB data lines */

resistor DM_series_R (DM_connector_side, DM_chip_side);
resistor DP_series_R (DP_connector_side, DP_chip_side);

/* we can now bring in the FT2232D block */

FT2232D_block FT2232D  (.GND(GND),
			.VCC(P_5V),
			.VCCIOA(VCCIOA),
			.VCCIOB(VCCIOB),
			.USBDP(DP_chip_side),
			.USBDM(DM_chip_side),
			.RESET(P_5V),
			.RSTOUT(RSTOUT),
			.PWREN(PWREN),
			.ADBUS(ADBUS),
			.ACBUS(ACBUS),
			.SI_WUA(SI_WUA),
			.BDBUS(BDBUS),
			.BCBUS(BCBUS),
			.SI_WUB(SI_WUB)
	);

resistor DP_pullup_R (DP_chip_side, RSTOUT);

/* power bypass caps */

capacitor P_5V_cap (P_5V, GND);
capacitor P_5V_cap2 (P_5V, GND);

endmodule