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doc: update for v1

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King Kévin 2022-06-27 15:19:28 +02:00
parent 2006dc0a0a
commit 9c6284cdde
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README.md
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@ -1,14 +1,14 @@
the USB bug detector identifies USB type-A cables (or devices) with integrated circuits.
<img src="picture/v0_front.webp" title="front" height="250"/>
<img src="picture/v0_back.webp" title="back" height="250"/>
<img src="picture/v1_front.webp" title="front" height="250"/>
<img src="picture/v1_back.webp" title="back" height="250"/>
usage
=====
to use the USB bug detector, follow the steps provided on the back of the board:
- insert a CR2025 or CR2032 coin cell battery in the USB bug detector for it to be operational
- insert a CR1220 coin cell battery in the USB bug detector for it to be operational
- press on the RESET button to arm the test
- the BUGGED LED should be off
- plug the USB cable in the USB receptacle
@ -17,32 +17,15 @@ to use the USB bug detector, follow the steps provided on the back of the board:
after the test, to save power, press again on the RESET button.
to ensure that the USB bug detector works, after pressing on the RESET button, press on the TEST button.
to ensure that the USB bug detector works, after pressing on the RESET button, press on the SIMULATE button.
this will simulate a USB plug with integrated circuit.
the BUGGED LED should switch on.
this also ensures the battery is not empty.
when the LED is on, the USB bug detector draws 3 mA.
when the LED is off, the USB bug detector draws 64 nA.
this results in a idle battery life of 419 years (for a typical 235 mAh CR2032 battery).
this is more than the self life of the battery (~ 1%/year).
fabrication
===========
the board has an optional READY LED (with accompanying resistor located next to it).
only populate it to debug the board.
the READY LED will we on when the BUGGED LED isn't.
this allows to always check if the battery is empty, but this also drains the battery even when not testing because an LED is always on.
the first prototype of the board (v0) offers three populating options, depending on the available NOR gate part and package:
- 1x SOIC-14 package: U1+C1
- 2x SOT23-5 pachgae: U2+C2, U3+C3
- 2x SOT-353 package: U3+C3, U5+C5
only populate one of the options, depending on the availability of the NOR gate part.
note: the Cx decoupling capacitor is not really necessary and is just present for good design.
this results in a idle battery life of 62 years (for a typical 35 mAh CR1220 battery).
this is on par with the self life of the battery (~ 1%/year).
mode of operation
=================
@ -61,8 +44,8 @@ this minimum 1.6 mA current draw is often caused by the decoupling/bypass capaci
when charging, the capacitor acts as a short for a small time, allowing current to flow.
on USB plugs with just resistors, or LEDs, the resulting current flow is not large enough.
the TEST circuit simulates an integrated circuit by putting a 100 nF capacitor across the USB receptacle.
the SIMULATE circuit simulates an integrated circuit by putting a 100 nF capacitor across the USB receptacle.
because of the 1 k Ohm inline resistor, and limited 3.3 V provided by the battery, a maximum of 3.3 mA can be drawn by the USB plug.
because of the 1 kOhm inline resistor, and limited 3.3 V provided by the battery, a maximum of 3.3 mA can be drawn by the USB plug.
this is often not enough to power up integrated circuit properly, particularly if they use a radio interface.
thus it is safe to use the USB bug detector on bugs, without activating it.