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201  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open ***full prototype pics*** on: August 02, 2013, 08:21:35 AM
Slightly less than 100 grams for an H-CARD. So a complete system with 16 cards and M-BOARD + Raspi would be under 2 kilograms.
202  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open ***full prototype pics*** on: August 02, 2013, 04:52:15 AM
Its my understanding that the sockets on the m-board are spaced 20mm apart, but how far away is socket "F" from the nearest mounting hole (or from the edge of the board)?
From center of socket "F" to mounting hole is 7.56 mm. From mounting hole to board edge is 5 mm.
203  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open on: July 30, 2013, 03:06:18 PM
Thanks to Cscape for hand-assembling these boards!  This is long, neck-wrenching work to do all this by hand!
Wow, that must of have been painful. Im completely useless with a soldering iron.. but the little I have done makes me appreciate anyone capable of doing work on this scale.
Nearly all the work is done using reflow technique, so there's very little hand soldering involved, but a lot of manual picking & placing with fine tipped tweezers. Each board has 240 capacitors in 0402 size, and about 60 other components.
204  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 30, 2013, 09:10:20 AM
How deep is this queue and what happens if you add one more unit of work than the queue can hold ?
Does it abort the current job ?
The queue is 2 deep. One job it is currently working on, and one job scheduled for later. Every time you poll the chip to see if the job is finished, you supply the next job at the same time (it's in the same SPI transfer), so typically the next job will be sent a few times. I've never seen any evidence of aborted jobs. I figure it just overwrites the next job.
205  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 30, 2013, 09:06:15 AM
Its probably based on ngzhang's original Icarus design which goes to sleep after finding a valid nonce, behavior based on a misunderstanding of the bitcoin hashing algorithm since more than one valid share can be found for any given getwork, though it is relevant for solo mining. I don't know why nobody has fixed this since the FPGA code has been public for quite a while now.
The bitfury design continues searching the nonce space and will report all that it finds. Only when the search is exhausted, it switches to the next job. It has a FIFO with the 15 most recent nonces found. If you don't supply the next job in time, it will restart old work and you end up with dupes.
206  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 30, 2013, 07:47:44 AM
Haven't had time to get a board up yet, but if it behaves like bitfury's fpga, just try sending it the new work prior to completion.  So to test, find a work that does not find a solution and one that returns a nonce very quickly.   Send the one that does not find a nonce, then immediately send the one that does.  Then measure the return time for the expected nonce.

I don't know how the FPGA works, but on the ASIC, the chip is working on job #0, while you send data for job #1. As soon as it finishes job #0, it automatically switches to job #1. Sending job #1 does not abort job #0, so if there's a way to abort #0, it must use a different mechanism.
207  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 30, 2013, 07:18:33 AM
How often does the work change ? I don't know if bitfury chips can be interrupted. For normal mining, I just let them finish the old work (takes on average 1.5 seconds), which is acceptable since the work only changes every new block (nominally every 10 minutes)
...
Wait what?
Work should change at least every 30s at worst every 60 seconds.
Are you designing hardware that is inherently BAD for bitcoin?

I meant a prevhash change of course. Like I said, the firmware uses stratum, so it generates new work all the time.
208  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open ***full prototype pics*** on: July 30, 2013, 07:02:21 AM
What is the size of the mounting holes on the m-board?

Mounting holes in the PCB are 3.2 millimeter, designed for M3 metric thread.
209  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 30, 2013, 06:30:46 AM
Not sure if it resets just the SPI or the entire chip, but you may try using "SPI RESET sequence - rise MOSI and toggle SCK" https://bitcointalk.org/index.php?topic=228677.msg2411738#msg2411738
That just resets the SPI chain. I use that every time before I poll the chips to see if they are ready.

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Is there a doc (or list) of the data commands or the only place is the source?
All I know about is bitfury's postings in this thread and his source code, and neither mentions an 'abort job' feature.
210  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 30, 2013, 05:49:23 AM
How often does the work change ? I don't know if bitfury chips can be interrupted. For normal mining, I just let them finish the old work (takes on average 1.5 seconds), which is acceptable since the work only changes every new block (nominally every 10 minutes)

If there's a way to interrupt bitfury chips, I'd be happy to modify the firmware to support quick work switching.

Edit: I looked it up. Apparently work changes every 10 seconds, which would make the 1.5 second delay too much. So, it all depends on whether the bitfury chips can be interrupt. I don't know that yet.
211  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open on: July 28, 2013, 04:58:42 PM
I was thinking more about shriking the H-boards, not the m-boards. right now, there is a decent gap between each bitfury chip that could surely be reduced with some design revisions or adjustment of resistor placement. However, this would still increase the heat density...

Yes, the gap is purely for spreading heat. There only a few little components, and a few traces between the chips, so, electrically, the gap could be reduced to almost zero. It's the heat that is a concern.
212  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open on: July 28, 2013, 06:17:30 AM
there is a decent amount of PCB space between boards. Is there a reason for that, or will version 2 boards be designed more densely in order to shrink the size?
There are no plans to shrink the size right now. Of course, the closer the boards, the more difficult it will be to get the heat out. Maybe after more real-world data, a size shrink could be done.
213  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 28, 2013, 05:03:36 AM
1. Did the MOSI=1, SCK=1, SCK=0, MOSI=0 sequence change?

By looking at bitfury's source code it seems to be happening in a different order:
(presumes GPIO_10/MOSI is 0), (presumes GPIO_11/SCK is 0), SCK=1, (repeat 16 times  MOSI=1, MOSI=0), SCK=0

or instead of :
"SPI RESET sequence - rise MOSI and toggle SCK"
do:
"SPI RESET sequence - rise SCK and toggle MOSI"

The code is correct. Toggling SCK for a reset wouldn't make sense, because that's the same as writing data.

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2. SPI configuration - Does the chip read the MOSI data on SCK rising or falling edge? Judging from the code above it seems that while SCK is high MOSI shouldn't change, so it is likely on the rising edge - is that correct?

Also, does the chip output date on the MISO on SCK falling edge?

You can see in the code that the initialization code says mode=0, so it's using SPI mode 0 (data valid on rising edges)

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3. SPI speed - is there a minimum speed? Can I clock the chip (SCK) at 10-50kHz? Or even lower?

Also - what is the maximum speed? (or what is the fastest observed one - that anyone has successfully tested with?)
AFAIK there's no minimum speed.  Not sure what max speed is (I think it's > 10 MHz). I'm running the SPI bus at 500 kHz, which is about the fastest you can get for 16 chips in fasync mode.

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4. Does the piece of code below work because the 0x04 value (100 command) is preceded by a bunch of zeros? (e.g. chip is reading 000 and treating it as NOP)?
Code:
void spi_emit_break(void) { spi_emit_buf("\x4", 1); }
void spi_emit_fsync(void) { spi_emit_buf("\x6", 1); }

Yes.
214  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 28, 2013, 04:50:44 AM
The only limitation is the 4KB memory set aside for the coinbase data, which may be too small in some cases.

can you explain further what you mean by this?

If you look at the stratum documentation, you see it involves merging together coinbase strings plus the extranonce, and then performing a double SHA256 hash over the result. Now, the coinbase strings can -- in theory -- be very large, and this will overwhelm the limited memory inside the embedded device. Right now, I have a 4KB buffer for the total coinbase data.

In practice, most mining pools have coinbase strings that are just a few hundred bytes.

Also note that really large coinbase data may also not work very well on devices like the Raspberry Pi. Even though they have more memory, the hashing speed is still limited, and performing the SHA256 hash over a megabyte of data to generate a piece of work may slow down the device to the point where it has an effect on total hashing speed.
215  Bitcoin / Hardware / Re: [ANN] US/North American Bitfury sales now open on: July 27, 2013, 06:31:10 PM
I think an upper edge slot brace is a good idea.  These are hand made prototypes, so Cscape used the caps he had on hand - I know he recommended a larger cap along the way too, so perhaps you are seeing the newer assembled boards vs the boards he made a couple weeks ago.

There was a mismatch between the capacitor shape on the board, and the capacitor mentioned in the parts list. I ordered the (smaller) caps on the BOM, but noticed it didn't really fit well on the footprint on the board. I put the small ones on anyway (with hand soldering it is just possible to do that), but ordered the bigger ones for a better fit, and used those on later boards.

Electrically they both work, so there was no need to replace the smaller ones on the first couple of boards.
216  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 27, 2013, 08:34:17 AM
I don't know how p2pool works, but the firmware only supports stratum right now.

Does p2pool require a ton of memory ? Because that's probably going to be the limiting factor on the small CPU.

Edit: Note that every network connection also requires buffers, so maintaining connections with multiple peer doesn't sound like it would fit. However, you may still run the main p2pool software on a PC, and just offload the hashing to the board using getwork protocol.
217  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 26, 2013, 12:07:36 PM
The problem with a completed embedded solution is that the pool management portion sucks (based on reading about asicminer blades). They dont support stratum, and lack rich pool management features that cgminer offers, like switching pools using API, having more than 2 failovers, and so on..

The firmware already supports stratum and 4 different pools with automatic switching if a pool is non-responsive. The only limitation is the 4KB memory set aside for the coinbase data, which may be too small in some cases.
218  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 26, 2013, 12:05:02 PM
If properly designed you need only one type of board. One populated fully, other 8 just with regulator. And this also opens perspective to make other communication solutions like USB to SPI bridge and control via PC (or RPi).
Yes, you could make the same board, and populate one partly. It still means you have to interconnect them some way. Suppose someone makes a case for it, that case will also need an extra opening for the interconnect, and then you'll have unprotected 3.3V CMOS level signals going from one board to another, with potential ESD and EMI problems.

The board already has an option for RS-485 interconnect (it's on the unpopulated 3 pin connector along the side). That would be more suitable for board-to-board communication. Of course, that would still require the CPU, but that's only $5 @ qty 1000. I'm not too convinced the RS-485 is so great either. This board, with 16 chips, is targeted towards the small home miner with a limited budget. Put it in a nice case with power supply, and you have a neat little standalone unit.
219  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 26, 2013, 11:39:23 AM
The LPC + Ethernet is more like $15. That's less than a single ASIC. For a complete system with fan, heatsink, maybe a case, 12V power supply, the difference in cost is hardly worth the effort of having two types of PCBs and a new interconnect.

For lots of chips, the M/H board system is a better solution. Of course, an interesting option would be to replace the Raspberry Pi with an integrated CPU/Ethernet on the M-BOARD.
220  Bitcoin / Hardware / Re: [ANN] Bitfury is looking for alpha-testers of first chips! FREE MONEY HERE! on: July 26, 2013, 11:13:46 AM
Another question. What is CPU load at your board? If it's not to big you may consider to place expansion port on your board and split SPI to more simpler boards (only with DC/DC regulator). I think that good switcher can be this part http://www.digikey.com/product-detail/en/SN74CBTLV3251PWR/296-9129-1-ND/378104.
CPU load is less than 10%, so it could easily drive a lot more chips. However, most of the cost is in the DC/DC regulator and the ASICs, so it wouldn't actually save that much money.
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