[quote author="jbeale"]I would have thought that power rail noise correlated to USB packets would be mostly because of current drawn from the power supply to drive the USB signaling voltage by the USB transceiver block, rather than just capacitive coupling? But I have not looked at the circuit myself.[/quote]
probably contributing to some of the noise.
the ft232 d+ and d- pins are backwards imho. the usb traces on the board are horrible, it is such a small area to get a good differential pair layout out. one is 2x the length of the other on V3a, it is better on V3b and V3.5 but one trace is still on the bottom.
V4 could use some clean up around the usb lines too, but much better than previous versions.
the usb lines are very close to the main regulator and uneven length and spacing. the noise on the power is time correlated to usb packets, between usb packets the noise is magnitudes better. a layout revision is needed to minimize the capacitive coupling between power and usb.
the usb signals are still far from clean, I recommend using only a usb cable with ferite cores at each end.
I have added a 100nf ceramic cap parallel to C21 and c23, this seems to drop the noise down quite a bit.
C22 and C24 are still tantalum, I have not changed them yet but noise is down on the respective rails.
I have been looking into this using my V3a pirate, there is no doubt in my mind this can be improved with better filter caps. i think i have isolated the source of the noise too, time is short right now but ill update after more testing.
many computers have(or have option) been employing spread spectrum clocking to decrease emi. This type of clocking scheme is difficult to gauge drift.
any wire or trace has resistance, inductance and capacitance to it, in certain circuits the ageing of components, oxidation of traces, or orientation of parts(just to name a few), can affect resonant frequency. However... unless there was immediate and major physical changes to the clocking circuitry or an over abundant supply of cosmic rays, you would not be able to tell the difference just by using it. us humanz don't have the resolution.
it is most likely the standard bloat windows experiences after many hundreds of updates and installed programs and drive fragmentation.
I have used the quick connect fittings(like on back of dispenser) in industrial settings, mostly where there is no movement of tubing. however if your pressures won't exceed 30 or 40 psi you should be alright with using them as long as the cut in the tubing is square and the tubing is flexible enough.
I would also install a excess flow shutoff valve from your supply to the dispenser. this can prevent the wild octopus situation if there is a connector/tubing failure.
several years ago I was maintenance mechanic at a water bottling facility. One day inside the fill room, one of the workers uniform shirt buttons got caught by the conveyor, pulling him around the filler and nearly pulled him through a microwave cap sealer, before I managed to hit the Estop.
as far as I know there is still no Estop in that area, and all uniforms still have buttons.
during a major upgrade, they installed some bossy cart stacking machines that used hydraulics, when we were adjusting the PLC for proper timing the bars that pushed a full shelf of bottles on to the cart would engage during the update process, if there was water on the rack they would be broken and water would soak everyone in a 20ft radius. I could only imagine how bad it could get if someone was clearing a jam and there was an error. needless to say we had installed a second hydraulic shutoff next to the control panel.
from some industry friends I believe California has banned the use of these carts, they will weigh over 1200# when fully filled with one gallon water bottles. I have witnessed several accidents/neglectful situations involving these carts.
[quote author="Zeta"]Do you know if the buspirate can program Silabs' ARM MCUs?[/quote]
from what i have read the SiM3 uses same programmer/debugger in a SWD or JTAG mode. the silabs debugger is fully capable of SWD as it is not significantly different from the C2 interface.
I have found that the smaller connectors can delaminate from the board, otherwise that is a great price, perhaps a test of the ability to resist seperation from shock is in order.
I have found it usually was between 1.5x and 3x. the one i was using never had less then a 150mm focal distance below 3x, I guess it was just the right combination of eyepiece and objective.
at one point I was using it 6+ hours a day for 4 or 5 days a week, regular breaks and stretches were mandatory!
