Continuing to loop the cold value is known behavior as mentioned earlier in the thread. I could have coded the loop to kick out after the second write but it's not hurting anything.

I have not tried writing the firmware back after telling the IPE it's the wrong chip with only 1.75KB of code space instead of the required 3.5KB and also the wrong device ID, but I can see why it would throw the errors you're reporting.

Yeah, it's pretty standard.

I bet 550MHz and 630mV would do you about 800W and give you 3.7TH per machine. 620mV might do that frequency stable but it's the threshold speed for that voltage on my machine. If yours has a bit slower chips it might not run stable without pushing the voltage a bit more. Also consider that it'll run hotter for about a minute and a half (maybe around 850W?) until it drops into cold voltage, so hopefully the PSU is good for that.

Everything's just a standard 0.1" holes; once you pull the fan and look at the board it should be pretty obvious what's what.

Yeah, but text doesn't carry near the data payload of a picture and I don't cater to lazy folks.

http://gekkoscience.com/img_stash/S7LN/S7LN_HEX.zip

The above link is a ZIP archive containing some 17 hex files. The one called "S7LN_PIC_FIRMWARE.hex" is the original unmodified firmware found on the hashboards in my S7LN.

The remaining files are called "S7LN_userselect.X.production.AAA-BBB.hex" where AAA represents the cold running voltage and BBB is the hot running, in millivolts average per node.

I have cold-running files from 580mV to 690mV, where the hot is 30mV higher. I also have three files that set both hot and cold to the same for 700, 710 and 720mV - at those points, a clock rate that would require a higher voltage to start would also draw enough power to smoke out the whole board. Pretty sure anyways. I've tested up to 775MHz and 1020W wall (stock setting was 680W on my unit) without finding an unstable clock on even 710mV and I don't want to catch my boards on fire.

Anyway. If you want to make use of this, find yourself a PIC programer (I use a PICKit 3 that I've had since about 2013) and grab the MPLAB IDE software. What you'll actually need is the IPE side (Programming, rather that Development) but I'm not sure it's possible to download just the IPE without getting the whole thing.

If you remove the outlet fan from the unit, at the end of the boards you will see eight pinholes - one pair, and one set of six. The six are the ISP header into which you'd plug your PICKit.


The lowermost hole of the six corresponds to the header-socket hole on the PICKit that has been flagged (on mine there's a while triangle pointing to it).


You'll want to set the IPE "Device" drop-down to PIC12F1572. Under the "Settings" select Advanced Mode, and once in there click Power, set VDD to 3.3V and check "Power Target Circuit from Tool". For that to work right you're going to want to unplug the 18-pin cable from the board before you program it.

Once that's all configured, plug your PICKit into the board (you might need some wires or pins to connect the header socket of the programmer to the holes on the board) and click "Connect". If you did everything right, there ought not be any errors. Might get a box pop up saying something about low-volt programming and voltage mismatches or some such; just click "OK" and carry on. As far as I can tell it doesn't matter for this application.
You should be able to read existing code off the chip, which you can see in Memory View (View -> Show Memory). If you would like, click "Read" to pull all the existing firmware off and File->Export->Hex to save a backup copy just in case.

Click the "Browse" button associated with the Source path, and navigate to the new hex file of your choosing. Once that's loaded, click "Program" to push the new program to the board.

Make sure you plug the 18-pin cable back in before trying to mine again.

The program will turn on your board to the hot-start voltage value upon power-up of the controller board. The S7's software, once the OS is booted, will run cgminer for about a minute to get things warmed up and then restarts it fresh. My board firmware will start the cold running voltage about 35 seconds into the second cgminer run. If you're watching on a kill-a-watt, the power consumption should drop about 10% or so when it kicks over to cold-running.

I've been killing the miner by killing mains AC into the PSU. My meter box is wired with a switched outlet. I've power-cycled it probably 50 times and it's come back up every time.

Well it's something that's just come up in the last few days, basically I've been asked for assistance on a project with the benefit of being able to piggyback my own project on some of their resources. But since I'm just an assistant and tagalong I don't think I have the right to talk about anything yet. But yeah, it's an exciting possibility if it works.

When I noted I could run 50C boards in a 73F ambient at 20% fan and 2TH, I was at home and running the miner overnight about five feet from my head while sleeping. A lot of the tests have been at the shop, where the ambient has run between 90F and 100F for pretty much the entire time. I'm pushing it about as hard now as I ever have (710mV 775MHz for 1018W of draw) and I'm seeing 63/65 from about 90F ambient, fans 3120/3240

All the S7 hack links are in the first line of my sig - the thread and the group buy.

All things being equal, temperature should be proportional to total power dissipation. As your power input goes down, your heat output goes down. So yes, the thing will stay cooler at lower frequencies.

I'm not sure how much I can talk about, and nothing's official yet, but I may have been given a solution to "no access to chips, no access to specifications and parts".

The thread's linked in my signature. I'll be updating that chart with more values and stuff, and should have a hex file package and flashing instructions posted today or tomorrow. I'm kinda behind on that.

I've done extensive testing on underclocking and undervolting. Got mine to run 2TH at 20% fan and about 415W. Operating at low frequency won't really cause instability; the problems happen when you choose a frequency that is too high for the voltage (or a voltage too low for chips to operate at any frequency, since all semiconductors have a minimum operating voltage).

I cleaned out a computer once that had been run by a chain smoker. There was so much tobacco gunk caked inside that it looked like the case has been filled with Grape Nuts cereal. You couldn't pay me enough to scrub that out with a toothbrush.

That's four or five people now with interest again. I'd say it's enough for another round.

Completely off topic, but "deserve" is one of my least favorite words.

Probably best to try that with something better than S7 chips, especially with the halving and that S7 is going on a year old. But the idea is sound (as it always has been).

With board-level power measurements it would be easy to write a control program that optimizes the voltage and hashrate for a given power dissipation and target error rate.

You want some to play with? I'm already booked solid on stuff I know what it is. And, to be fair, some of them came from your miners anyways. I figured on putting up a sale post sometime to get rid of 'em anyway, I got about a dozen.

Yeah, 620 is a good setpoint. Assuming mine is a representative sample, the group-buy miners will be programmed with 650/620 unless otherwise specified, and shipped set at 450MHz for 2TH at a shade over 400W. That does give the owner still a lot of room to play, including getting close to stock speed (since 550MHz versus 600MHz only costs about 225GH) but saves close to 200W. All those numbers are given with free-running fans, by the way. Turning fans down will save a shade of power on fans, but as chip heat increases the chip-level power requirement increases for a given voltage and frequency. It's a tradeoff.

Once the group-buy batch miners start arriving about Tuesday I'll be able to get measures from a bigger sample set and compare.

This fix does not apply to S7 Batch 1 boards, since it deals with the board's voltage regulator and there is none on the 54-chip boards, just the 45-chip boards from later batches.

Who knows, there might be an all-software option ironed out by then. I did get a PIC firmware dump from an S9 but I'm not quite up to reverse-engineering a 3600-byte PIC program since I just started learning the instruction set last Friday.

Oh, you know it is. And they'll probably continue to ignore the cgminer open-source license terms. It's easier to hide advanced features from peasants like us.