YES. RTFT.


Also, no it's not impossible to make ROI. It's impossible to make positive ROI. But it's not impossible to learn more than the asking price worth of basic concepts when you have a tool that is simultaneously powerful, flexible and inexpensive. Beginners are people too. As for what you were trying to ask with your question, see above. Then see the very first post in this thread and then see almost literally every other post in this thread if that doesn't give you a comprehensible answer.

Thanks, Steve.

Also, just to report - the rigged prototype has been running at 200MHz (11GH/s) off 630mV and about 700mA (approximately 0.32W/GH) for 68 hours with 12 HW errors reported. I'm okay with that.

I think I've eaten maybe five McDonalds hamburgers in the last eight years or so. Most of them were either free or discounted, and none of them I was really satisfied with. I tend to not eat fast food burgers because, when you grow up on a farm and there's literally 40 head of Angus living in your backyard your standards for beef quality are a bit different. There really aren't many good burger joints here in town - pretty much none, actually. It's a cheapskate college town so there's lots of franchises (and pizza places, and four Subways) but not a lot of decent dives. The next town over has 1/5 the population and a lot better non-crappy eatery options. The local Casa de Waffle has pretty good burgers (and potato mountains), and I really like that I can watch the food being prepared. I know exactly how fresh it is.

One of these days when I have extra money, I'm thinking of taking one evening a week and going to every restaurant in the county (a different place each week) and ordering the best burger on the menu. So by the end of a year or whatever, I'll have an index of every good (and bad) burger around.

Also, no I haven't talked to Bitmain in a couple weeks. They handed us off some NDA paperwork to look over before they'd talk pricing in detail, and of course right after that we started getting in hardware to build and test so I haven't even read past the first page.

I shifted that 0.3BTC out the other day to pay for celebratory sandwiches after we hit the efficiency goal with some regulator tweaks.

I reckon tomorrow I'll go back over some Bitmain paperwork I've set idling and probably get caught up on heatsinks as well. Fetching chips will be the first big determining factor if this stuff goes beyond prototype.

Thanks, but naw. My ethics don't permit me to get food from clubs I don't participate with. I didn't even get the free pizza from random presentations and stuff while I was in college. As with everything else, I prefer to pay my way. Friday Cheeseburgers are a Waffle House $2 special, but our Tuesday sandwich time at Waffle House came from me feeling bad about only showing up on discount days so I would get lunch there at full price another time during the week to help make up for it.

Also, two hours after the last time I ate a McDonalds cheeseburger is the only time in my adult life that I've had to request a pitstop while on the road. For emergency diarrhea. Fast food is for the most part no longer considered "food" in my book, so don't bother using it in comparisons.

That's the only way to do it. My opinion is, if you can't be polite while also being honest - be honest. Being right doesn't make you bulletproof, but it does make you right.

Well technically, the one time we've done a preorder sale in the past (last June or so, for our DPS2000 first batch) we missed the deadline by a week. But part of that is because the PCBs were delivered from the etch house nine days late, so it's probably pretty good that we only overshot the deadline by seven.

I'll make no decisions for sure until after we have those prototypes in hand. If I have to redesign something it'll add two weeks to whatever expectations we might already have.

As for grabbing the money and running, too many people know where our shop is for that plan to work out if we ever tried. I'll admit I'm a bit nervous about the whole process, partially because of comments like this one. I'll admit Novak and I talked about how much fun it'd be to run a hardware scam like that, coordinated with a trusted member or two to fake a hardware review of a "prototype" and then start taking in preorder money. Then pay it all back with a note saying "you just got scammed, thank goodness it was only a test" to help convince people they needed to be more dilligent. And having said all that, I technically now have no way to convince people that isn't what we're doing here.

Yeah, they were taking more than that much from individuals, more than a few. A Compac preorder I'm not too worried about, but a TypeZero path would probably be an order of magnitude larger so any steps taken now need to be evaluated based on future steps as well.

I should probably get back on the paper trail with Bitmain about chips. If we can't get chips from them fairly readily, nothing else matters.

Compac PCB prototypes were ordered today, only about 1.5 hours behind schedule but a fair amount of that was because I spent the extra time designing a new BM1384 breakout board on which I can more effectively test parallel and string configurations. This coming week I'll be working on beefy regulator design which will end up going on the TypeZero (and probably other things that are way behind schedule), and once the new boards come in and Compacs are tested, I'll start Amita testing with the new breakout board. Hopefully there's no trouble and I can get the Amita design completed soon.

There will be no bulk discounts for the Compac. The price is the price. If you want to middleman and resell on eBay, I reckon that's fine but your inventory cost will be the same as anyone else's. I need to go back over pricing with the new design and get a bead on the actual costs so I can reevaluate the sale price, but hopefully $20 is still within reason. The Amita will have the same regulator as the Compac (I need only change two parts, I think, to get the higher voltage range out of it for a two-chip string), and then a second chip, second heatsink, 40mm more PCB and probably another dollar in support components so if the Compac sells for $20 hopefully the Amita can sell for $30.

So, question. Assuming we can get, say, 1000 chips from Bitmain, how do we want to divide them up? We could do 600x Compac and 200x Amita, or 700x Compac and 150x Amita, or something like that. Where's demand? How should we apportion things? Additionally, if Compacs cost approaching $20 to make, making 600 of them means about a $12K investment to run out the full batch. How much of this should we try to out-of-pocket, and how much should we try to gather - and by what means - before ordering materials for the batch? So basically, should we attempt a pre-order to pay for parts and get everything done in one go, or should we build as resources allow and only sell in-hand miners (at reduced and somewhat drawn-out quantities)?

Not one satoshi will be requested until after prototypes of the final design are dispersed and thoroughly tested by trusted members of the community. Do not trust anyone claiming to represent me if he acts in contradiction to this policy.

I stand by what I said. I just finished going over the PCB design and found a few corrections. Novak might take a look at it this afternoon. I expect by 4PM or so we've placed an order for prototype PCBs. The last batch arrived in a little over a week. So that gives us half a week to assemble and test a handful of boards. In that time I also need to get some heatsinks shipped in but that shouldn't be difficult.

We're already behind on my estimated timeline, mostly because of jacking with that effin' regulator. If I'd done it "right" (and by "right" I mean avoid complex monolithic options and go with modular reduced complexity, which is our general design preference) I'd probably already have protoPCBs in hand.

I won't make any estimate about TypeZero or Amita boards. My task this afternoon will be to conjure up a better BM1384 breakout with integrated parallel and string chips so we can get them in the same proto batch. Next week the focus will be on TypeZero regulator design (about half of which is already done) and testing. I'll probably have a second Compac regulator test board I can refit for Amita voltage levels. If that works, and the string test board works, I'll start modifying Compac PCB to Amita PCB.

For any reference of design steps so far, the first Compac board design was V0.0 and the current is V0.3, so it's undergone three major revisions of circuitry and physical layout. Shouldn't have taken that many changes to get something right. I'm annoyed by this.

Right now I'm planning on sending test Compacs to philipma1957, CrazyGuy and MrTeal (if they'd be willing to help out, and also get me their addresses). I respect their knowledge and opinions regarding market demands, customer use-cases and overall engineering quality.

That is one of our primary goals, always has been. Slow starting on account of we won't take in investor, speculation or dev-preorder money out of principle, but hopefully we can get rolling here soon. First thing in the morning Novak and I need to give the Compac PCB a once-over, and if it checks out we'll be ordering prototypes. With any luck, two weeks from now we'll have sample units in a few hands for testing and review.

I have about half a dozen New R-Box on the shelf that we got busted off CrazyGuy and rebuilt. Those are nice little units, and kinda meet the same niche that we'd like to do with individual TypeZero boards.

I'm not sure how stable the buck driver was at the higher frequency either. My outputs I was seeing pulses in the 800KHz neighborhood. The inductor behaved well at 600KHz off the IR3899.

But yeah, reducing core losses in the inductor was likely a contributing factor in improved efficiency.

So, got some new charts for y'all.



I got to thinking about some of the design choices on the regulator, specifically FETs and operating frequency. I'd been working around 600KHz previously, and the new buck driver had stock setpoints at 500KHz and 670KHz so I opted for 670. Going up in frequency keeps inductor ripple current low, which keeps output voltage ripple low with a given output capacitor ESR. It does, however, introduce increased losses from gate drive switching. So I figured I'd test at 500KHz (where the inductor ripple was still pretty reasonable) and I saw an increased efficiency.
Then I got to looking at the FET transition times compared with the dead times from the controller. If your rise and fall times are long, this increases conduction losses from operating in the linear region (between full-off and full-on). If the delay times are too long, you can get shoot-through losses when both FETs are temporarily on. The FETs we had spec'd for our Chuckwagon project had better transition times, though the delay times weren't that much better. They also had a slightly lower Rdson, which is to say the on-state resistance. The power losses in the top FET, since it's only on about 15% of the time, are dominated by switching losses. The bottom FET, however, is on the other 85% of the time so its conduction losses (resistive losses, current squared times Rdson) dominate the switching losses. The Chuckwagon FETs have a higher gate charge, which increases switching losses in the top FET, but between the lower shoot-through losses and the lower conduction losses in both the top and bottom FETs, I still saw a net efficiency gain over the original FETs at 500KHz. A side benefit was, for some reason the output noise was much better. Possibly this is because of reduced switching noise or shoot-through currents, but the output was cleaner even than all of my tests with the first regulator design (the IR3899). So, it adds about a quarter to the total cost to use the different FETs but I'm pretty sure the benefits outweigh the costs.

Especially when I can operate it at 606mV 150MHz 8.25GH/s with 500mA draw on the port.

Bitmain could probably do it if they wanted, but with a fixed-voltage string it comes down to balancing high hashrate versus chip density. When I first ran the numbers for a potential S2 upgrade kit I was eyeballing something like 3.5TH off 1KW with 100W blades, but their prototype was more like 2.4TH off 6 blades at about 700W probably because you could do it with a lot fewer chips. To get low power means clocking the chips at their bottom end, and to get high hashrate at bottom clock means a jillion chips.

If I can work out strings at those voltages, it means the bottom-end efficiency for the TypeZero should be comparable, if not better.

Yeah, it's pretty much what I was expecting. The Amita numbers should be slightly better, since the regulator will probably be around 90% efficient at 1.2-1.4V and auxilary losses (CP2102, LEDs and such) will be constant per stick, so halved per chip.

Also, 150MHz is 8.25GH, so yes 8.63GH is better than what's possible and whoever told you those numbers is wrong.

Tomorrow my priority will be to finish the Compac PCB design and give it a good once-over. Hopefully we can get those ordered on Friday. If possible I'll draw up a two-chip breakout board so we can test parallel and string better, which will be good for Amita and TypeZero work. While waiting for that stuff, I'll probably shift back to inline regulator design and stuff for the TypeZero. Depending on how much I like the buck chip on the Compac, I may try to build around it for the TypeZero as well.

So, I ran efficiency lines for 675mV and 700mV today. But it's super boring and I could discern general trends - plus running above 700mV is not "recommended" as at that point you can already push a chip far enough to draw over 1A from the USB. Suffice to say, it appears to work well.

And now the moment you've all been waiting for - actual performance data. The breakout board I used for testing has a bad RF pin so the LED doesn't work properly, but other than that sporadic flashing load (which is probably more than made up for by the LEDs on the USB/UART adapter) I have what should be a pretty accurate mockup of the final Compac circuit running behind my USB meter. Apparently the U3 code in cgminer only recognizes 100-250MHz so that's the range I tested in until we are able to alter the code.



Specified hashrate vs measured power for 600-675mV. Testing above this voltage range was moot, as I could not take the hashrate higher than 250MHz (13.75GH) with the software available.



Here we have a chart of the actual measured W/GH for the Compac. I was surprised but I did get the chip to light up 200MHz (11GH) off 625mV so I'll leave it there for the night and see how it works. This corresponds to 3.52W or 0.32W/GH on the performance data. My ideal stock setpoint, 150MHz 600mV, yielded me 511mA draw which puts it at 2% higher than USB power technically allows. I think the final board should be slightly more efficient which may pull this into acceptable range though 511mA is actually probably good enough. If we're able to adjust the code for arbitrary clocks, 8GH corresponds to 145MHz which should pull about 495MW and I'd just stick it there for defaults.

I did get the chip to start at 150MHz off 595mV, which dropped my current consumption to 504mA as measured. And once started, the running voltage should be adjustable to a bit lower setpoint.

The turn-on current burst for higher frequencies continues to be a killer; I need to adjust the overcurrent limit resistor on the regulator board because when I tried to start 675mV at 200MHz and above it actually dropped out and had to be power-cycled a few times before it survived the burst. I think I saw the bench supply tap 2.4A out briefly, which is pretty toasty.

So yeah, here's the raw data.

600mV	GH	Iin	Pin	W/GH
100MHz	5.5	372	1860	0.34
125MHz	6.88	448	2240	0.33
150MHz	8.25	511	2555	0.31
625mV
100MHz	5.5	390	1950	0.35
125MHz	6.88	464	2320	0.34
150MHz	8.25	544	2720	0.33
175MHz	9.63	620	3100	0.32
200MHz	11	704	3520	0.32
650mV
100MHz	5.5	410	2050	0.37
125MHz	6.88	495	2475	0.36
150MHz	8.25	575	2875	0.35
175MHz	9.63	660	3300	0.34
200MHz	11	760	3800	0.35
225MHz	12.38	850	4250	0.34
250MHz	13.75	945	4725	0.34
675mV
100MHz	5.5	440	2200	0.4
125MHz	6.88	530	2650	0.39
150MHz	8.25	610	3050	0.37
175MHz	9.63	715	3575	0.37
200MHz	11	810	4050	0.37
225MHz	12.38	915	4575	0.37
250MHz	13.75	1020	5100	0.37

It's not difficult, especially if you have a dummy hub without built-in power protection. Cut the 5V trace from the upstream jack, add beefy wire (preferably in a star pattern) from your power input to the 5V pin on each port. Ideally, make sure there's some good buffer caps (470uF or so) near each port. There's surely enough information running around here (and who knows where else on the internet) from the last two years of stickminers being a thing, so I'm not going to gather and encapsulate information that's probably already readily available.

We're definitely going to add power pads to the Amita for running in external 5V at higher current. I haven't decided yet if we'll do that on the Compac, but probably not. Should be able to get around 16GH out of it off the 1.5A the USB jack is rated for, which is pretty toasty. Stock settings for the Amita will probably be in the 800-1000mA range, but it'll probably be built to take up to 2.5-3A if you can keep it cool. That'll be a step for another week, is recalibrating my regulator prototype for 1.2-1.6V output and seeing how well it behaves.

I've already got code written to calculate the PLL hex values for close-to-arbitrary clocks. Software's Novak's job, and if we implement a cgminer driver for these instead of just using the U3 driver already there, we can put that code in it and get about an order of magnitude more granularity in clock setpoints.

Right now it looks like 11GH should be possible on 750-800mA of hub power. That's sturdy, but not difficult.