FreeCalypso > hg > freecalypso-schem2
view venus/src/usb/usb_domain_bctl.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 | 9309cebe07b8 |
line wrap: on
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/* * This module encapsulates the USB domain circuit for boot control. */ module usb_domain_bctl (GND, P_3V3, ChanB_RTS, ChanB_DTR, CTL1_out, CTL2_out); input GND, P_3V3; input ChanB_RTS, ChanB_DTR; output CTL1_out, CTL2_out; /* pull-up resistors on FT2232D outputs */ resistor ChanB_RTS_pullup (ChanB_RTS, P_3V3); resistor ChanB_DTR_pullup (ChanB_DTR, P_3V3); /* open drain buffers */ logic_ic_common od_buf_common ( .Vcc(P_3V3), .GND(GND) ); capacitor od_buf_bypass_cap (P_3V3, GND); buffer_slot_basic buf_CTL1 (.A(ChanB_RTS), .Y(CTL1_out)); buffer_slot_basic buf_CTL2 (.A(ChanB_DTR), .Y(CTL2_out)); endmodule