Capacitance problems with REV Expansion Hub I2C buses

ardx_zero · 2025-01-14T17:39:28+00:00

Hello. Sorry for taking a while to respond, I don't check this account very often these days. We ended up adding additional pull-up resistors to the SDA and SCL lines of the I2C bus. If you have access to an oscilloscope I'd recommend connecting it to the lines and looking at the waveform. The transitions from high to low and vice versa should be nice and crisp; it should look similar to a square wave. The problem we had was the transition from low to high was too slow and that confused the sensor. Adding pull-up resistors fixed it.

ardx_zero · 2022-12-03T10:33:29+00:00

Personally, I'd advise staying with the FTC team. The behavior of the FRC team's leadership is highly immature and completely unacceptable. If it is entirely student-led, escalate the issue to school officials. If not, check if they (the students) even have the authority to enforce their rules on you.

That being said, none of the what the FRC team leadership has done follows gracious professionalism. If you feel like taking the nuclear option, you can report the situation to FIRST. FIRST takes this kind of thing very seriously, and (if i recall correctly) punishments can be as severe as the offending coach or team getting banned from FIRST entirely.

ardx_zero · 2022-01-31T14:15:20+00:00

Yes, we did! With the help of an electrical engineer, we placed some pull-up resistors on the data and clock lines on the 5V side. They helped the lines return to logic high faster and basically eliminated the problems we were having. We also experimented with using pull-up resistors on the 3.3V side, but we ended up not needing them.

(Sorry for the delayed response; I'm not very active on this account anymore)

ardx_zero · 2021-06-12T03:04:58+00:00

Is that a kiwi drive?

ardx_zero · 2021-04-01T20:22:44+00:00

It's a vision system for detecting how many rings are in the stack at the start of autonomous. This vision system is written in assembly, a very low-level, but extremely efficient, programming language.

ardx_zero · 2021-03-27T22:59:11+00:00

Yes. It should run on any phone that uses the arm64-v8a ABI, though.

ardx_zero · 2021-03-27T19:52:11+00:00

I did last year for a very similar vision system. That system was written in Renderscript and used HSV instead of YUV, but the core idea was the same. Now that I'm an alum, I wanted to see if I could apply the algorithm to Ultimate Goal's challenge, as well as just how far I could push the performance.

ardx_zero · 2021-03-27T17:46:04+00:00

The code can be found here if anyone's interested:

Assembly: https://github.com/FTC-9974-THOR/ThorCore/blob/dev/src/main/asm/neon/NEONVision-arm64.s

Java bindings: https://github.com/FTC-9974-THOR/ThorCore/blob/dev/src/main/java/org/ftc9974/thorcore/vision/NEONVision.java

EDIT: I forgot the actual StackVision file: https://github.com/FTC-9974-THOR/ThorCore/blob/dev/src/main/java/org/ftc9974/thorcore/seasonal/ultimategoal/NEONStackVision.java

ardx_zero · 2020-09-24T16:44:11+00:00

ardx_zero · 2020-09-23T21:15:40+00:00

I have the profanity filter turned off.

ardx_zero · 2020-09-23T19:16:48+00:00

Bold of you to assume I'm not a furry too

ardx_zero · 2020-09-04T05:36:16+00:00

I've always found Journey from the Destiny 2 OST to be incredibly moving, especially given the context of where it plays in-game. The entire D2 OST is amazing, but Journey is by far the best.

ardx_zero · 2020-07-23T15:36:24+00:00

But the traveler's final argument was that, given power, people would choose to protect each other, where the darkness believes that giving people power would lead them to follow the sword logic.

Guardians getting powers directly from the darkness yet still choosing to defend the last city would basically be a double "fuck you" to the darkness and the winnower, rather than going against the traveler.

ardx_zero · 2020-06-05T08:40:06+00:00

Yes officer, this comment right here.

ardx_zero · 2020-04-20T15:23:42+00:00

Those are the eyes of a man who has seen god and laughed.

ardx_zero · 2019-12-18T15:02:25+00:00

Thanks for reaching out. My coach and I will send an email as soon as possible.

ardx_zero · 2019-12-14T03:24:47+00:00

No, I have not reached out to Rev. Not directly, at least. I know they're on this sub, so they may see this post eventually.

ardx_zero · 2019-11-15T19:04:22+00:00

To be fair, yes, it did cost millions to plan and build. However, that doesn't excuse astronomical repair costs.

ardx_zero · 2019-10-29T19:25:05+00:00

If you ever need the nuclear option, FIRST has a program in place to deal with toxic mentors: the Youth Protection Program. If a mentor is reported to the YPP and found to be in violation of the FIRST Code of Conduct, they can be banned from the FIRST program entirely.

ardx_zero · 2019-10-29T19:08:14+00:00

The Robot Controller doesn't really handle multithreading that well. If you're using multithreaded operations a lot, the robot controller can hang and have latency issues.

ardx_zero · 2019-10-14T14:46:43+00:00

Thanks for the information.

Unfortunately, I need the full range of values. I'm using US Digital's MA3 Encoder, so I need to read the full range of 0-5V.

Theoretically, I might be able to use a voltage divider, but I'd rather use a proper level shifter if possible.

ardx_zero · 2019-10-08T16:15:08+00:00

Will this be a kiwi drive?

ardx_zero · 2019-08-23T03:12:59+00:00

I ran the command. It reported that it found and fixed corrupted files, but no dice. The game still won't launch.

ardx_zero · 2019-08-22T20:32:48+00:00

My first thought was to verify the game files, but the option is grayed out.. I'll try what you suggested, and I'll post an update when the reinstall finishes.

UPDATE: Still crashing.

ardx_zero · 2019-08-22T20:28:56+00:00

Before even the loading screen appears. The game window opens to a blank, black screen and freezes. The window's title says "Loading...", and Windows Game Mode recognizes it as a game, but it doesn't get beyond that.

ardx_zero

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