From 9c6284cdde0b832dd61a2a4b16b6c87f8dbc8a9d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?King=20K=C3=A9vin?= Date: Mon, 27 Jun 2022 15:19:28 +0200 Subject: [PATCH] doc: update for v1 --- README.md | 33 ++++++++------------------------- 1 file changed, 8 insertions(+), 25 deletions(-) diff --git a/README.md b/README.md index bdd4d44..84ba187 100644 --- a/README.md +++ b/README.md @@ -1,14 +1,14 @@ the USB bug detector identifies USB type-A cables (or devices) with integrated circuits. - - + + 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.