GekkoScience BM1384 Project Development Discussion

[philipma1957]

Oh, Mr Sidehack, with your usb miner design, you're using the CP2102 yes? do you have esd/power spike protection on the data lines from the USB to the chip? (i think some smd capacitors from each data line to earth should do it i have to double check the data sheet)

just a thought, since I've has nothing but bad luck with things that run from CP2102s (hand full of usb block eruptors, a zues miner, my "new R-box's" all with fried Silabs chips)

I have had a lot of block eruptors in the hundreds very few failed. My 100gh r-boxes all worked well. 

Do you have power supply issues?
Do you overclock?
Did you fan cool the usb sticks?

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[sidehack]

So, I think I found the problems with the Compac as designed. The ground noise issue was pretty well solved by tying the SGND and PGND together at the ASIC, which neutralized the potentials between local grounds for the VCore and 0.9/1.8V logic power. I also noticed some issues with the regulator occasionally dropping out during startup of the device, because chip init can draw a heft burst current (as noted in previous tests). The output capacitance on the buck was being overwhelmed and tripping out the regulator. I solved that by adding output capacitance in the form of a 470uF tantalum scavenged from a dead Habanero. Which, if anyone's ever stolen parts from a dead Habanero you know that whole PCB is one giant friggin' heatsink. Seriously those things are stout. But with the added output capacitance I was able to start the stick at 650mV all the way up to 250MHz (13.75GH) without issue.

I think the reduced output ripple also caused the ASIC to run more stable, because power consumption was down a bit overall.

Right now the stick is hashing away at 610mV 150MHz (8.25GH) drawing right around 520mA off my test hub. That's 0.32W/GH, not too shabby.

The burst output issue will probably be resolved when we have working dedicated drivers. The S5 code ramps the chips up pretty slowly and I don't see that burst on init like we see with the U3 driver. Hopefully we have working code by the time an Amita is released for testing, since there's no way to test it without working code now is there?

Anyway, so now I have about a dozen PCBs that can be modified to work as a single-chip stick miner. I'm thinking of sending some to my first-wave testers even though it won't be the final product (and probably a homemade heatsink approximating the final) so they can at least start playing with it. I'll be working over the PCB design, checking over the 18-board design, and probably sending off both to fab tomorrow. Once the PCBs for the Compac return and test functional, I can send off for Amita PCBs also since it's an extension of the same design. Boy I sure wish I'd had these errors fixed a couple weeks ago.

The final design will have a different UART level shifter setup, a slightly changed regulator layout (to accomodate the changes in input and output capacitance) and probably a different potentiometer because I don't really trust the one I got right now. If you're playing rough with it and the wiper gets disconnected from the contact surface you'll sorta feed the ASIC with 2V instead of the <0.8V you were going for. I tend to adjust the pot with the Compac unplugged and using a multimeter to set it (which requires the formula for voltage based on pot resistance). I'll probably change the design up a bit to make that fault safer, but probably also spec a new pot anyway.

[OgNasty]

Nice!

[ZenFr]

Very good news :-).
Congratulations !

[philipma1957]

looking forward to testing it!!

[sidehack]

Do you want a jerryrigged one to play with? If I have time tomorrow I might put a few more together, since I already have some mostly assembled that would need to be modified. The end result circuitry would be pretty much identical so efficiency and such would be unchanged.

[philipma1957]

Do you want a jerryrigged one to play with? If I have time tomorrow I might put a few more together, since I already have some mostly assembled that would need to be modified. The end result circuitry would be pretty much identical so efficiency and such would be unchanged.

maybe What software will run it?

[novak@gekkoscience]

Do you want a jerryrigged one to play with? If I have time tomorrow I might put a few more together, since I already have some mostly assembled that would need to be modified. The end result circuitry would be pretty much identical so efficiency and such would be unchanged.

maybe What software will run it?

It detects under the icarus driver as an Antminer U3.

--
novak

[sidehack]

Yeah, we're still ironing out the details on a driver (novak is busy with some other pretty sexy engineering these days and some cgminer code is labyrinthine) but it enumerates in stock cgminer 4.9 as a U3. Volt setting is irrelevant since that's hardware-implemented, but the frequency setting works and it works with a single chip without issue. Multiple chips we're still working out, and the miner init pulls extra power that wouldn't be a problem with a proper driver, but in general, it works. I've used stock 4.9 for all the single-chip testing so far.

[AJRGale]

Oh, Mr Sidehack, with your usb miner design, you're using the CP2102 yes? do you have esd/power spike protection on the data lines from the USB to the chip? (i think some smd capacitors from each data line to earth should do it i have to double check the data sheet)

just a thought, since I've has nothing but bad luck with things that run from CP2102s (hand full of usb block eruptors, a zues miner, my "new R-box's" all with fried Silabs chips)

I have had a lot of block eruptors in the hundreds very few failed. My 100gh r-boxes all worked well. 

Do you have power supply issues?
Do you overclock?
Did you fan cool the usb sticks?

floating ground to earthed ground (psu connected devices + laptop = esd off laptop to psu via whatever means) i'll PM you the full details if you want, im not going to hijack this thread about it.

[PlanetCrypto]

0.32W/GH is damned impressive/amazing.

Fricking incredible.

[sidehack]

Yeah, it's okay. Pretty great for a stick miner, and our full-scale miner boards would include the same adjustment range.

[AJRGale]

0.32W/GH is damned impressive/amazing.

Fricking incredible.

and thats off a chip that you see been quoted as 0.5~0.6W/GH elsewhere... don't hold me to them numbers though, not fact-check myself here

[sidehack]

I trust the chart in the S5 thread first post (https://bitcointalk.org/index.php?topic=902305.0), which lets you know that the chip is pretty underutilized so far. If my calculations are correct (I need to wear glasses to really pull off that phrase) if the S4+ used BM1384 chips, you could run six strings (instead of 4) getting 4TH (instead of 2.5) off the same PSU. It should be possible to get close to 4TH out of an S2 upgrade kit if done right (by which I mean chip density and such, which is more expensive). The BM1384 is a darn good chip, but since it's better at top clock than anything else is at bottom clock they've felt no real need to increase density and take the W/GH lower. Now that some other outfits are putting out good numbers we might see the bottom end power range actually utilized, or we may see a new chip that's even better.

[SavellM]

Good Job Sidehack!

Cant wait to start USB mining again for fun

[Rabinovitch]

they've felt no real need to increase density and take the W/GH lower

But what about global warming?.. How could you, Bitmain, ignore this?.. 

I don't really care about it, but Bitmain, what about energy bills of your customers?

[sidehack]

If I send any out, I'll send them out to the first-wave testers to start playing with. When the redesigned PCBs come in and I can get an initial test on them, I'll send them out to first- and second-wave testers probably at the same time. Maybe after that I'll auction off some prototypes to help fund the project as a whole.

If you want to help with software, you're gonna have to talk to novak because that's his department. For this project I'm pretty much strictly hardware.

[TheRealSteve]

It detects under the icarus driver as an Antminer U3.

Might be worth setting up a USB PID under openmoko, pid.codes, or some other entity that's not entirely playing by the rules and giving out PIDs.  Makes it easier for various software to know what device it's dealing with and adjust options accordingly.

[valkir]

Great job sidehack and novak! 

[novak@gekkoscience]

It detects under the icarus driver as an Antminer U3.

Might be worth setting up a USB PID under openmoko, pid.codes, or some other entity that's not entirely playing by the rules and giving out PIDs.  Makes it easier for various software to know what device it's dealing with and adjust options accordingly.

Not necessary to detect under cgminer.  Most hardware uses the same USB-UART chips, with factory default PID and VID.  Now, it probably is worth getting a driver together, especially for the larger boards with more options besides clock adjustment.

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novak