GekkoScience BM1384 Project Development Discussion

[valkir]

Sidehack to help you on the founding, I whilling to run some of these USB for you with pleasure.
When ready, I will host them for free (since I paid a fix price for elect) and test them for you.


Just let me know what would be the shipping price and we could manage something.

We could do something similar as NastyFan and make a community around your design. I will be more than happy to help on that!  

[RadekG]

If I had an already-profitable miner I'd probably run it full-bore until it hit breakeven returns, then underclock/volt it about halfway and keep running it until breakeven returns again, and then take it down to the bottom. That's just what I'd do, I haven't checked the numbers to see if it'd be better or not than running it at bottom speed the whole time.

A lot of chips dissipate most heat through the top. ASICMiner's BE300 would have been a top cooler; so is the Rockerbox and all those other big-die chips. There's no requirement for string design to have capacitors on the bottom.
I guess I don't honestly know if it's designedly a top-cooler chip, but one of the reasons for doing that (especially the chip was designed to be string'd) is because in a string design you have multiple local ground planes all at a different absolute ground potential and if they short through your heatsink things can catch on fire if your PSU doesn't trip out first. Maybe I'll test out heatsinking on our breakout board and see if one on top or one on bottom keeps the chip cooler, but that'll only matter for the USB miner. The TypeZero would have to be top-cooled so the heatsink doesn't kill the power planes.

One good thing about building a flexible miner (and by flexible I mean with software-adjustable voltage and clock) is you can make it a high-speed miner or you can make it a super-efficient miner, whichever you want. Our board should have better low-end efficiency than the S2 upgrade's fixed operating point. Actually, two of our TypeZero boards should be just about equivalent to one S2 Upgrade board (by chip count), but ours can operate at both higher speeds and lower speeds because it's not a fixed voltage. A single board can operate like a U3 (that's why we chose our board size and USB connectivity), except you'd be seeing a similar price and quite a bit more hashpower.

There is good demand for not-crappy not-crappily-priced USB sticks. We will do our best.

Also, Guy tells me they actually scrapped out all their Hammer ASICs.

How far are you with testing heat dissipation? AFAIK most of the chips are made bottom dissipated, this is done because high power chips are usually soldered on heatpad, so heat transfer through solder balls (or pads) is better bottom. Don't know if BM1384 is this case. Also, this can be seen on A1 chips or older BM chips... Different situation is with big-die chips, they are upside-down with direct or indirect contact to heatsink.

I thought that string design needs bigger capacitors closer to Vcore pins to bypass transients caused by chips current draw variation.

[sidehack]

Did I miss a post? I never saw that he said he was putting off the 1.3th upgrade kit style for stick miners or to make money to produce others?

We're not putting off the TypeZero, if at all possible. But the USB stick miner is basically a tangible dev milestone between having nothing at all and having the full product. Since there's not a lot of extension required between having a one-chip miner and a two-chip miner, and between a two-chip miner and an eighteen-chip miner, and since our one-chip test bench will already be 80-90% of a working USB stick miner, there's no real reason not to go the extra 10-20% to make the complete product if 1) many people want them and 2) it's an affordable learning tool to introduce noobs to bitcoin.
We haven't stated outright that we'd be using sales profits from the stickminer to fund the TypeZero, but honestly that's what's going to happen. We got a bucket to put money in from whatever sales we have of whatever products and services, and then we pull money out of that bucket to stay in business. Profits won't be much from stickminers; selling 1000 sticks probably won't make enough profit to fund 50 of the TypeZero boards, but it's a start.

Once we have our breakout boards in hand and working, I'll complete a PCB design for stick miners. That'll be sent off to a board house for proto PCBs and while waiting for them, I'll work on TypeZero layouts. Then we'll assemble and sell stick miners while completing TypeZero layouts and getting prototype boards for it. Then once that's tested and working (and verified by some trusted hardware guys, probably talk to Philipma and MrTeal to start) we'll look into taking in money for a full manufacturing batch - contingent on chip availability from Bitmain, which it looks like might have a couple months' lead time. Which ain't exactly the best thing but if we can get everything else ready early and then the final step is dropping the BM1384s on the boards, testing and shipping, shouldn't be the end of the world. But it's not great.

How far are you with testing heat dissipation? AFAIK most of the chips are made bottom dissipated, this is done because high power chips are usually soldered on heatpad, so heat transfer through solder balls (or pads) is better bottom. Don't know if BM1384 is this case. Also, this can be seen on A1 chips or older BM chips... Different situation is with big-die chips, they are upside-down with direct or indirect contact to heatsink.

I thought that string design needs bigger capacitors closer to Vcore pins to bypass transients caused by chips current draw variation.

I am nowhere with testing heat dissipation. All I know is, every existing BM1384 miner uses heatsinks on the chip tops. I'm assuming the manufacturer knows what it's doing, and since the S5 seems to have no problem drawing 10W per chip out the top (and supplemented by airflow over the board with the aid of the side panels) I'm gonna assume it works that way until I have the setup to do direct testing.

String design does need large capacitors to buffer current transients (and therefore voltage transients) at a node level, and the S5 does have smaller caps immediately tied to the VDD pads probably to compensate for trace and lead inductance and ESR of the node-level caps. Keeping a constant node voltage and current is a stiffer requirement for string designs than for parallel VRM designs.

[chiguireitor]

We likely will be building one- and two-chip stickminers. They're great for learning, which is one reason we want to make even the USB sticks with adjustable clock and voltage. Noobs can learn the basics of pools and wallets and cgminer CLI and even a bit of hardware tweaking for $20 instead of having to buy a $400 machine.

Sure it makes no financial sense to buy a stick miner if all you're looking at is the bottom line profitability. But not everyone looks only at the bottom line profitability - myself included. I made more coin from learning about the hardware itself and using that knowledge for repairs and upgrades than I ever made mining. Some folks just want a first-tier tool to play with and try to understand how a thing works before going big. Why tear down a Corvette to learn about engines when you can take apart a lawn mower first?

That's some true homebrew dedication! I believe some people have been scared away from mining because of this.

We're not putting off the TypeZero, if at all possible. But the USB stick miner is basically a tangible dev milestone between having nothing at all and having the full product. Since there's not a lot of extension required between having a one-chip miner and a two-chip miner, and between a two-chip miner and an eighteen-chip miner, and since our one-chip test bench will already be 80-90% of a working USB stick miner, there's no real reason not to go the extra 10-20% to make the complete product if 1) many people want them and 2) it's an affordable learning tool to introduce noobs to bitcoin.
We haven't stated outright that we'd be using sales profits from the stickminer to fund the TypeZero, but honestly that's what's going to happen. We got a bucket to put money in from whatever sales we have of whatever products and services, and then we pull money out of that bucket to stay in business. Profits won't be much from stickminers; selling 1000 sticks probably won't make enough profit to fund 50 of the TypeZero boards, but it's a start.

I'd buy some from you! Probably one or two, just to help funding and give them away to my relatives. I believe that you could do a better miner than bitmain, and would love to see some high density products coming out from your lab. Maybe oil cooled from the start, etc.

[SFMiner]

I'm in for a small batch of stick drives to help fund development of the TypeZero.  Hopefully you can do quantity discounts; I would love to be able to give these to friends/family so they can get into Bitcoin on a small scale.  Helping BTC adoption one USB stick at a time.

Regarding the TypeZero - I haven't mined with S1s since last August, so perhaps someone with the technical knowledge feels like designing an inexpensive DIY frame/housing for TypeZeros.  I would love to be able to rack mount these.

Any thoughts? 

[RadekG]

How far are you with testing heat dissipation? AFAIK most of the chips are made bottom dissipated, this is done because high power chips are usually soldered on heatpad, so heat transfer through solder balls (or pads) is better bottom. Don't know if BM1384 is this case. Also, this can be seen on A1 chips or older BM chips... Different situation is with big-die chips, they are upside-down with direct or indirect contact to heatsink.

I thought that string design needs bigger capacitors closer to Vcore pins to bypass transients caused by chips current draw variation.

I am nowhere with testing heat dissipation. All I know is, every existing BM1384 miner uses heatsinks on the chip tops. I'm assuming the manufacturer knows what it's doing, and since the S5 seems to have no problem drawing 10W per chip out the top (and supplemented by airflow over the board with the aid of the side panels) I'm gonna assume it works that way until I have the setup to do direct testing.

String design does need large capacitors to buffer current transients (and therefore voltage transients) at a node level, and the S5 does have smaller caps immediately tied to the VDD pads probably to compensate for trace and lead inductance and ESR of the node-level caps. Keeping a constant node voltage and current is a stiffer requirement for string designs than for parallel VRM designs.

I used IR thermometer to check S5 chip temps and I discovered big difference between chips and also temp sensor. Chip variation is about 15 degrees, but diff between temp sensor and chip temp is up to 25C which shows high thermal resistance Rthjc and also imperfect heatsink mounting. I am sure small USB miner will not see such troubles.

I see that when one pair of chips draws less (and voltage increases) whole chain goes down. I've seen diode array which I guess is OV protection of each pair, do you plan to add this protection also or it is not necessary for 2 chips string? How about to add balancer like Li-Po batteries? Or simple capacitor divider? My S5 has voltage variation from 0.77V to 0.81V what makes it less efficient I think.

[sidehack]

I think we are specifically not going to offer bulk discounts on miners. Recall that one point of this project is to aid home miners, which means we're not going to incentivize bulk buyers to make things worse for home miners. We'll keep the price reasonable and the price will be the price regardless of the quantity.

The S5's screws are pretty spread out, so there's lots of room for board warping which would gap some chips. Unfortunately that's not something we'll be able to really get around since it's basically the same as the S1, but we can maybe arrange our chips in a better stagger formation to keep loads even. I'm gonna try to rig a temp sensor to measure the actual heatsink instead of the board, and base fan speed control on that. The diode array I think you're talking about is actually the inter-node level shifters for IO. We're looking at a three-chip-wide string instead of two-chip-wide so any one chip won't have as much effect on the node's voltage. Capacitor dividers will also be implied by each node's buffer cap, which won't be small. The Prisma used a node-level FET as a backup current shunt to help keep voltages down on underperforming nodes. This doesn't really help efficiency since the power is being burned off in a FET instead of the ASIC, but it does help manage node-level voltages. I'm not sure how necessary it really is.

A 2-chip string miner will require decent node-level capacitors but proper regulation will be at the mercy of each chip's functionality.

[MrTeal]

Interesting, I don't have a Prisma to look but I always assumed the FET functioned as a shunt regulator to conduct if the voltage exceeded a certain threshold. Is the Prisma FET always conducting?

[MCHouston]

What exactly counts as a home miner?  Someone mining at home with residential electricity?

[valkir]

In my opinion Home miner is a miner that can run on a normal electricity plug. 120V 15AMP (around that )

With normal sound and heat. Something that you can (almost) plug and forget.

The S5 or the Avalon 4.1 are good example right now. The only problem is S5 sound.

I will be ready to paid a lot more for a good miner with max 1300 watt and quiet.

I prefer more chip ,less watt/gh, quiet and less heat!   

Go Go Go sidehack!

[sidehack]

Interesting, I don't have a Prisma to look but I always assumed the FET functioned as a shunt regulator to conduct if the voltage exceeded a certain threshold. Is the Prisma FET always conducting?

That's what I intended to say the FET was doing. I doubt it's conducting all the time. But if a node voltage starts to go up because the chips aren't running full current, the FET will take the rest of the current and pull the node voltage back down. It's a safety feature to make sure your chips don't overvolt, but the power it's draining would have been burned off in the chips anyway so it doesn't really improve efficiency.

What exactly counts as a home miner?  Someone mining at home with residential electricity?

Sub-KW miners I'd call home miners. S5, Avalon4.1, SP20 are examples of this. Though the SP20 is pushing it given that stock settings request over 1KW and they're balls loud at that speed. Something more like the S3 would be a "definitive" home miner for me. And let's not overlook the entry-level quiet desk miner like the R-Box or U3.

[notlist3d]

Interesting, I don't have a Prisma to look but I always assumed the FET functioned as a shunt regulator to conduct if the voltage exceeded a certain threshold. Is the Prisma FET always conducting?

That's what I intended to say the FET was doing. I doubt it's conducting all the time. But if a node voltage starts to go up because the chips aren't running full current, the FET will take the rest of the current and pull the node voltage back down. It's a safety feature to make sure your chips don't overvolt, but the power it's draining would have been burned off in the chips anyway so it doesn't really improve efficiency.

What exactly counts as a home miner?  Someone mining at home with residential electricity?

Sub-KW miners I'd call home miners. S5, Avalon4.1, SP20 are examples of this. Though the SP20 is pushing it given that stock settings request over 1KW and they're balls loud at that speed. Something more like the S3 would be a "definitive" home miner for me. And let's not overlook the entry-level quiet desk miner like the R-Box or U3.

What spec miner is your goal is it a all in one like the S5, SP20.  Or more small like R-box and U3 like?

[sidehack]

Please RTFT before asking questions that have already been answered all over the place.

FROM POST #140

Please RTFT before asking questions that have already been answered all over the place.

FROM POST #1:

The primary goal is to build a simple board which would be USB-connected to a controller, and capable of adjusting both core voltages and clock speeds using cgminer flags. We're looking at a single board capable of 300GH at 150W, downclockable to around 150GH 50W. At mid- or low-range settings it could be run off a brick with a quiet 120mm fan and heatsink and be a decen Jalapeno-formfactor home desk miner. The board will be designed specifically so that four of them would mount to an S1 chassis. Couple that with a 4-port USB hub and a Pi or something as the controller, and you have an "S1 Upgrade Kit" which will aim for 1.3TH at 600W clockable down to 600GH about 160W.
...
A secondary goal would be to design another board which could mount to a Prisma chassis. Modifying our design to a similar power density as a Prisma (1KW board-level) we could see a 2.4GH miner downclockable to about 1.1TH at 300W.

[richardamullens]

In my opinion Home miner is a miner that can run on a normal electricity plug. 120V 15AMP (around that )

Don't forget us in Europe.  I know it is premature to say this but why not also manufacture in Europe or China.  Perhaps Olimex could make miners.  I seldom purchase from America as the delivery charges are often excessive.

[valkir]

Yeah I understand that but normally you can run on 240 with lower amp so its better to make it for 120v 15amp so that everyone can use it. 

Dont worry you are lucky and you have 240v

[sidehack]

As long as the United States still has people that need jobs, we will never outsource manufacture to a different country.

[vs3]

Just my 2c - let's do less politics and more business

And one thing at a time - I guess it will have to start from somewhere, so if it is 120V - so be it. At the end of the day you will plug a power supply unit that will convert from whatever AC you have to (most likely) 12V or 5V which is what the board will use. I'm sure you can find a suitable PSU for every single country in the world. But that's a completely separate issue.

[sidehack]

Not outsourcing labor is one of the standard policies we've had since the beginning. The only reason to sell jobs overseas when people right here need work is greed, and some folks might have noticed that's not how we operate.

Also we're not building anything with a built-in PSU. So it doesn't matter if you use 120V or 240V. Just use whatever PSU you have.

[RadekG]

The Prisma used a node-level FET as a backup current shunt to help keep voltages down on underperforming nodes. This doesn't really help efficiency since the power is being burned off in a FET instead of the ASIC, but it does help manage node-level voltages. I'm not sure how necessary it really is.

I thought that Prisma's FETs are simplified on S5's by using few schottky diodes like zener, each regular diode has 0.7V treshold, but using two in series can restrict maximum voltage to 1.4V approx. per chip, or using three schottky can adjust max. voltage at different level, but temperature will affect it significantly. So I wish you good luck tuning this circuit.

Regarding size and power - I think there might be a demand for passive or ultra quiet miners for home miners - remember that most of us upgraded from Girlfriend 7.1 to Wife 1.0a who is very sensitive about our hobbies, especially when they are noisy. A heating panel with 450W can be good starting point, output power can be "programmed" by switch with pre-defined voltage/freq. Just on fly idea. Nowadays best eff vs ROI is around 0.75W/GHs.

[richardamullens]

I understand what you are saying and it is perfectly fair, but I said "why not also manufacture in Europe or China"

If you can't sell into Europe or elsewhere because of taxes or delivery charges then you lose nothing by also manufacturing elsewhere.

However, I applaud what you are doing.  Bitmain's U3 device used items that the home miner could easily source for themselves making it uneconomic to ship.  Do what you do best of all.