Topic: GekkoScience 2Pac/Compac BM1384 Stickminer Official Support Thread - page 69. (Read 177467 times)

Are the last few comments actual solutions directed at multi 2Pac owners, or are they plausible solutions but untested? I have a macOs and opened a second terminal window to run a second instance of cgminer from the same directory. I also tried duplicating cgminer-gekko directory and ran a different process of cgminer from the duplicated directory. Since all ASICs are recognized in all instances, how do you propose binding a specific ASIC to a specific process of cgminer?

Just run the same cgminer in second session with different parameters - you don't need two copies, and even if you did need two copies, why would you clone/make again when you can just copy the one that's already built...

I don´t know if it´s common here, but I use the deb package screen to login to a session via SSH. With screen you can keep the session running even if you log off. When reconnecting you can resume the session with the command screen -r. I don´t know if cgminer is able to run two instances in two different sessions. If it is you could start two instances with two frequencies.
Otherwise I would git clone cgminer in a second folder, maybe cgminer2, and compile it there. Then maybe you could start two cgminers in two sessions using screen.

I have some sticks where the ASIC performance is unbalanced enough I need to install a parallel resistor around one chip to get enough idle current for the node voltages to balance out and allow a stable startup when the reset RC goes high. A lot of those end up being "factory seconds" though - the chips are unbalanced enough that one'll choke out the other and go "zombie" at what should be a stable running voltage, so to work properly the whole thing has to be turned up past stock specs.

That's one of the issues with a single-wide string. The more chips you have in parallel on a single node, the more stable your string will be due to averaging. Node voltages will tend to average themselves out as weaker chips are randomly paired with stronger chips.

There's no mechanism for zombie recovery on the 2Pac. The string reset is a hardware RC delay that waits a fixed amount of time after the stick is plugged in and then enables the ASICs. The only way to re-reset is to unplug and replug, unless you know exactly what parts to short around on the stick. The original Compac had a reset testpad on the back which could be used for this, but the 2Pac is a bit denser and also has a heatsink on the back so I did away with those testpads.

The new pod miner in development has auto-recovery hardware that'll detect a string lockup (zombie condition) and power-cycle the string without manual intervention. The software to make this work properly is still being ironed out. It's a bit much for a stickminer though, but we'll see. Maybe on the next one.

I think you'll find they were all built with the same components, but electronic components have tolerances with which they are allowed to vary. The ASICs themselves will have some variation too, because at the sharp edge of processor implementation and design there are differences in the behaviour of individual processor dies cut from the same wafer.

Consider Intel for a moment. They fab a full wafer of Xeon chips intended for the high profit margin server sector. They slice the wafer and set each die in a substrate and wire it up, and drop the resulting chip in a test assembly. The test assembly runs each die at a variety of clock speeds and voltages, and the results of this testing identify a few dies as outright duds, and they are turfed. Some cores in a multicore die don't perform well, so Intel disables them and releases the chip as a hex core instead of an oct core. Some chips perform well on all cores, Depending on the clock speed and voltage each die will tolerate happily, the individual chips are "binned" as various frequencies. Some of the chips will run stably at crazy clock speeds, and these are binned as engineering samples or Extreme Edition CPUs, for which a huge profit margin is commanded.

The Bitmain ASIC chips will be the same. Some of them will go gangbusters and put up with ridiculous clock speeds without going wonky. Others will operate at more pedestrian speeds without failure. I seem to have a pair that will run at 500 MHz without complaint if I give them enough voltage and keep them properly cooled. I'm currently running them at 300 MHz because that produces the most work for my setup.

Philosophical waffling from me aside, if you have one 2Pac that has hardware errors at the same speed as another, and you have adequate cooling, turn the voltage up a little bit on the error-prone stick so it stops erroring. It's simpler than multiple cgminer instances if that's even a thing that works.

Not all 2Pac were built the same. Same voltage, but one throws many HW errors, another does a few HW errors, and the last one throws 0 HW errors. This is why I asked if I could run each device with their own frequency (Mhz). Rather than device number, the serial number seems like a better unique identifier and maybe use the GSx hardware model if necessary. Maybe something for cgminer-gekko 4.11

Good work. That suggests your trimpot is still in the default position as configured by sidehack during the initial test. At that voltage it should reliably run at 100 MHz, and possibly a bit higher.


Good choice.


Yes, the trimpot configures the voltage regulator stage on the PCB, and the voltage regulator controls the voltage supplied to each ASIC. You move the pot, the voltage changes, and this happens irrespective of the clockspeed you're running at.

At a given voltage, increasing the clock speed will increase the heat output of the chip, and put more load on your cooling solution. My understanding is that each time a transistor in a high density integrated circuit like a CPU switches from one state to the other, it loses or wastes a bit of electrical energy as heat. The more times per second you have the switches oscillating (ie. the higher the clock speed) the more times per second the transistors have to lose a unit of heat energy. So, running at a higher voltage but low clock speed will put less strain on the heat sink than running at that same voltage and a higher clockspeed.
Running at low clockspeed and low voltage will produce less waste heat than running at low speed with high voltage, so we choose the former condition if we can get reliable operation that way.

Generally speaking, CPUs require a lower supply voltage to run at a lower clockspeed. Modern PCs have power saving methods that automatically ramp down your computer's clock speed and voltage when the OS detects that the CPU isn't doing much. A bit like your car engine idling at traffic lights; no point running at redline if you're not doing any work with the engine.

When the workload increases, your PC will ramp up the CPU voltage and frequency, producing more waste heat, and consuming more power. The voltage is increased because operating at a higher clock speed needs a higher voltage supply to ensure reliable switching of the transistors in the CPU. I think this is due to inherent resistance and capacitance in the chip's die, but it's been a long time since I studied this and I am a barely educated buffoon in this discipline.

Your 2Pac stick does not have space age fancy automated voltage control systems which would increase cost and complexity. It does have a trimpot that lets you alter the ASIC voltage between a safe minimum and maximum range, letting you tune each stick for the minimum voltage at which it will stably run at your chosen clock speed. You need to make sure you can keep the chips cool at the voltage and clock speed you've chosen, because a hot CPU wears out more quickly, and a too hot CPU will just fry its delicate electronic circuitry.

Armed with your multimeter, a thermometer, and cgminer logs, you can determine the minimum stable voltage that your 2Pac will continuously and stably run at. Any higher voltage and you're wasting power and have to deal with more heat. Any lower voltage and your stick won't run continuously without errors.

It's possible to run a stick, and dial down the voltage until cgminer starts reporting hardware errors. (HW:0 in the cgminer status line will start increasing to HW:1 and above.) When you see this, you increase the voltage a bit until the HW errors stop incrementing. Then run it for a few hours and ensure you still have no additional HW errors, and you'll probably have found your stable voltage for that clock speed.

I haven't been able to restart a zombie without a replug. I intend to build a relay board controlled by the Pi3's GPIO pins so I can have a script detect a zombie and replug it automatically.


Not with a single instance of cgminer. cgminer takes a single --gekko-2pac-freq parameter and applies it to all detected sticks. It might be possible with multiple instances of cgminer and a cgminer.conf for each to limit which 2pacs a particular instance of cgminer controls, but with the cgminer conf Write function currently broken I haven't played with this. Oh, and I also only have one 2Pac at present.

1) When a 2Pac becomes a zombie, is there a way to restart it without having to manually unplug the USB device? Is there a parameter in cgminer, or USB Management setting that will do this for you?

2) Is it possible to configure different frequencies for each 2Pac attached to the computer?

^ this only if you have both compac and 2Pac
If only 2pac, then
On Linux PC or Rasp pi (this will donate to sidehack :
#work with freq table and power to see what voltage settings (see relevant links) you need to use if you want to adjust freq to 175, 200, 225, etc by replacing "150" with a different number

On windows PC

Hi there. Newbie to mining here but having fun with some frustration.

First page says I should input following on cmd line to overclock frequency

--gekko-compac-freq 200 --gekko-2pac-freq 150

Where do exactly do i put this?
after the word url appears or should i write as follows
url
stratum+tcp://stratum.slushpool.com:3333 --gekko-compac-freq 200 --gekko-2pac-freq 150

Thanks for advice in advance

Thanks for the instructions. I touched on each side of the capacitor. At rest, all three are 0.5 (furthest away from USB), and 0.75. Running, I'm seeing 0.62, 0.63.

I set multimeter on DCV 20. Centech: https://manuals.harborfreight.com/manuals/98000-98999/98025.pdf - page 5

Even if I change the frequency from 100, 150, 200, or 250 Mhz the reading is always 0.62 for both. So, this value only changes if I turn the trim pot clockwise? What is the role of voltage? Allow 2Pac to run more without HW errors in the higher Mhz?

make a folder and exclude it from your anti virus software

then  put the download in the folder.

I do a double  nest

folder 1
inside folder 1 I make  folder 2


inside folder 2 I drop the download

Apologies if off-site images are bad etiquette.


Set your multimeter to DC Voltage. This multimeter autodetects AC and DC voltage. Many multimeters require you to select AC or DC.

https://i.imgur.com/WRLMglT.jpg

Touch the multimeter probes on each side of the capacitor.

https://i.imgur.com/YBAf1Cq.jpg

Read the voltage on the multimeter's readout. ASIC N1 reads 0.7643 volts.

https://i.imgur.com/O8geaqV.jpg

Touch the probes on the second ASIC's capacitor.

https://i.imgur.com/EFw7opj.jpg

ASIC N0 reads 0.7490 volts.

https://i.imgur.com/vFdvI52.jpg

These measurements were taken with the trimpot in this position.

https://i.imgur.com/U1DY1ax.jpg

Turning the trimpot anticlockwise lowers the ASIC voltage.

https://i.imgur.com/ae02w0g.jpg

Lower voltage measured on ASIC N1.

https://i.imgur.com/pydVlRi.jpg


To reduce PCB flex and improve heat transfer from the ASICs to the heatsink I machined a small aluminium piece and attached heat transfer rubber insulator where the clamp presses against the back side of the PCB where the ASIC chips are located.

https://i.imgur.com/ECVY7Wz.jpg

Side view of the back side clamp, PCB, and heatsink.

https://i.imgur.com/nxPhgS2.jpg

cgminer running.

https://i.imgur.com/4IMz2PE.jpg

Are you on ckpool? You made 0.00047122 BTC or $2.78 USD so far?

Trying 175Mhz at 1.25A 4.89 V. Kept getting zombie sticks yesterrday running at 1.5A. I'm running 3 GekkoScience 2Pac on Port 1, 3, and 5.

Nothing, the led goes to the purplish colour and is not recognised.

My thoughts exactly.

Would have thought it more likely to 'fail' whilst running it, due to heat stress etc, but i've had it fan cooled the entire time and the heat-sink rarely got warmer than 'ooh thats warm'. To fail on start-up is unexpected.

That's disappointing. Does 1 faulty chip render the whole unit defective? Is it possible to be repaired? Thanks for the quick reply btw.

Poor little ASIC. You shouldna done that; here were jist a boy.

I'd bet one of the chips is roasted.

Hoping sidehack or vh can help me out here, or if someone else has an insight.
I've had two 2pacs running at 250Mhz (with a slight turn of the trimport) with fair stability for the past few weeks, all hunky dory. Up until today all was fine (bar the odd restart every few days), but earlier, i shut down both 2pacs for a system reboot and on firing them up again, one of the 2pacs is only displaying the blue led (it might be a mix of blue and green, so purplish) and is not detected by cgminer. The other is functioning normally (green with flashing blue). Can anyone comment on what this 'purple led' state might mean? Nothing out of the ordinary occurred when i shut them down today: stopped cgminer, removed 2pac... start cgminer, insert 2pac. Have tried on 2 known-good power supplies and also tried with a laptop (previously confirmed as working).
At a bit of a loss right now... grateful for any assistance.