view venus/src/periph/sim_socket_block.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 5b18183f55bf
children d33cb696b335
line wrap: on
line source

/*
 * This module encapsulates the complete SIM socket block:
 * the actual socket, the bypass cap and our SIM_CD circuit.
 */

module sim_socket_block (GND, Vio, VSIM, SIM_CLK, SIM_RST, SIM_IO, SIM_CD);

input GND, Vio, VSIM;
input SIM_CLK, SIM_RST;
inout SIM_IO;
output SIM_CD;

wire SIM_CD_inverted;

sim_socket_wrap socket (.C1(VSIM),
			.C2(SIM_RST),
			.C3(SIM_CLK),
			.C5(GND),
			.C6(VSIM),
			.C7(SIM_IO),
			.SW1(GND),
			.SW2(SIM_CD_inverted)
		);

/* cap per Leonardo schematics */
capacitor C306 (VSIM, GND);

/* pull-up on the switch line */
resistor switch_pullup (SIM_CD_inverted, Vio);

/* inverting buffer for SIM_CD */
inv_buffer_74LVC1G04 inv (.GND(GND),
			  .Vcc(Vio),
			  .A(SIM_CD_inverted),
			  .Y(SIM_CD)
		);

endmodule