thanks marto,
you did a great work in regard of overclocking!

hex16 running at 450MHz (52°C on asic, ~90W, 1350mV, 7GH, 1-2% HW erorrs) quite well,
500MHz works but a little bit hot (63°C on asic, ~110W, 1460mV, 7,6GH, 2-3% HW errors).
510MHz (1440mV) works, but hw errors go up.

1500mv has not worked. try undervolting the suggestions from:
https://bitcointalk.org/index.php?topic=303538.0


is there a temp sensor or at least a overheat protection at the board?
(if not - I will build something external)

if you see problems with more than 1 hex16a on cgminer startup - get a better hub! specially "genesis" usb hub chip seems to be bad.
symptomes: after usb device reset by cgminer it never comes back, in dmesg you see many usb errors
I use a raspberry pi as with cgminer 3.6.6.

try to use a power-cable for each hex16, I had quite hot cables when running 3 of them at a wire; also hw errors goes up because of voltage drop.
I use a corsair 650tx power supply for 5 miners, connected to the 2 pcie plugs.


used power connector from an old mainboard:
http://upload.confusion.at/bt/power.jpg

mounted the hex16a like a tunnel in a old pc case; one fan on each side, so one fan could die
http://upload.confusion.at/bt/case.jpg

2 days later - still no response from technobit as promised

Order IFYYLZIML from 2013-09-23, chips send to marto by SebastianJu at 2013-09-27
Order changed to "backorder" at 2013-10-15 - because out of stock?
As I changed from oder VPQSLLFPS / klondike design to hex16 design - also a overpayment of about 70eur exists.

But I never got any reply to my emails to technobit or messages to marto.

is this the next one who fools me?

yes (hopefully) the idle buck regulator do the noise.
You can try to hookup a small load (resistor, 50-100mA) to the regulator.

remove the shield of the usb cable.
only let red (5V), black( GND), white and green (data) go to the board.
the at least the ground-loop is cut off.

ferrite bead: perhaps you have a old mainboard lay around?

600khz buk reg: do you have mounted both asic bukregs? but only use 1 for the asics and the other one is "idle"

@bkkoins:
regarding the signal trace with inverters:
better place a capacitor near at each gate

the "new" signal looks good, pic spec states:
rx input pin have to be stable 10ns before falling clock and 15ns after falling clock.

How have you connected the outer shield of the usb plug to gnd?
I have often seen at various hubs - that the other shield is also connected via some ferrite beads to gnd.

usart timing is at page 375 of the pic datasheet - not what you searched in detail -but still interesting.

page 270 and page 271:
Maximum set-able baud-rate:
Desired Baud Rate = FOSC / (4 * (SPBRGH:SPBRGL +1))

48MHZ / 4 = 12MHz - thats "fast"

the dead-zone could be avoided if the nonce is read from the sram and then rearm the sram.
only after this send the next hash to the asic.
(and not much "time" is lot as not every hash gives a nonce?)

I will give it a try (already ordered the part)

regarding cpld:
There are no small pincount but many macrocell cplds available.
The smallest I have found is from latice with QFN 32, that has enough space to fit a i2c slave and the receive logic.

But if it's possible to go without cpld it would be the better way - but will need some rework of the isr handling.

for efficient cooling with water better use small pipes to achieve a turbulent flow (see Reynolds number).
german users find all neede info in this book:
VDI Wärmeatlas

another aproach is to use heatpipes, perhaps also fanless.

what about placing some connectors on the v2 design of K16 to piggypack a stronger powersupply on a addon board later?

@Vigil: buck regulator switches of at 145°C +/- 20°C
see page 39 of the pdf, the IRF will be very hot.
http://www.irf.com/product-info/datasheets/data/ir3895m.pdf

@nekonos:
see https://bitcointalk.org/index.php?topic=190731.msg2329781#msg2329781

serials come from each pic, read directly (master) or via i2c (slaves).

some updates from the i2c front (a little bit technical):

connect to pic with serial #1, notice the 3 attached slaves:
connect to 1st slave:
connect to 2nd slave:
connect to 3rd slave:


and now unplug usb and plug usb to pic with serial #2, without reset of the system, notice the 3 attached slaves:
connect to 1st slave:
connect to 2nd slave:
connect to 3rd slave:

I will forward the i2c code now to bkkcoins.

regarding I2C:

Hardware supported (which is the only possibilty at the slave) I2C is a pain - all states must be handled correctly else I2C will stall.
This means testing & debugging each step on master and slave (which is a lot of work because I have only 1 pickit).

Today I have finished the I2C code, seems to work now very well and without race conditions - fixed them today.
For tomorrow a test with 3 slave pics (currently only 1 during development) is planned.
If everything works - I will send the code to bkkcoins.

math

price at rs-components is 30,56eur for 1 with 12V fan.
not really "cheap" but I will give them a try when everything is ready.

k16 is too big (100x100) and heatsink is max 50x50:
http://www.fischerelektronik.de/pim42/upload/fischerData/image/web/lam5.jpg
http://www.fischerelektronik.de/web_fischer/de_DE/K%C3%BChlk%C3%B6rper/D02/Miniaturl%C3%BCfteraggregate/PR/LAM5_/index.xhtml

or sub-optimal solution:
http://www.fischerelektronik.de/pim42/upload/fischerData/image/web/la5.jpg
http://www.fischerelektronik.de/web_fischer/de_DE/K%C3%BChlk%C3%B6rper/D04/L%C3%BCfteraggregate%20mit%20Axiall%C3%BCfter/PR/LA5_/index.xhtml

yiha!
batch 5 ist endlich voll!

the nxp i2c buffers are cool - did i2c at 300m cat5 some years ago