view venus/src/periph/led_mosfet.v @ 70:8bc2aa52fd23

manual RESET button new part: 260 g force, shorter actuator One of the main envisioned use cases for FC Venus is field demonstration: the board will be carried around, mounted on a sheet of acrylic or somesuch, it will have a battery and an antenna connected, there will be a test SIM with active service inserted, and the setup will be ready to demonstrate as a working phone at a moment's notice. But when a demo is not actively in progress, the fully assembled setup will be transported around in a big and loose ESD bag, and it will need to be equivalent to a traditional phone in its switched-off state: battery present, RTC keeping time, but not switched on all the time. Having a RESET button of the same keyswitch type as used for the regular keypad and PWON would cause a problem for such field transport scenarios: any spurious press of this button would cause a "misc boot" switch-on. Short spurious presses of PWON are filtered out by the firmware (automatic power-off if the button isn't held down long enough), but the same cannot be done for super-low-level nTESTRESET. However, a button with significantly greater operating force and a shorter actuator (not sticking out to the same height as the regular keypad buttons) should be much safer.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 02 Dec 2021 22:40:39 +0000
parents 06e95ff0023b
children
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/*
 * This module captures the circuit for showing the state of a digital signal
 * on a LED without loading that digital signal by driving the LED from VBAT
 * and using a MOSFET to control it.
 */

module led_mosfet (GND, VBAT, Signal);

input GND, VBAT, Signal;

wire R_to_LED, LED_to_Q;

resistor R (VBAT, R_to_LED);
basic_LED led (.A(R_to_LED), .C(LED_to_Q));
mosfet Q (.G(Signal), .S(GND), .D(LED_to_Q));

endmodule