Last known issue fixed

[FlapJack]

Very interested in this shitty cable notification feature. Other than that, I can see it being useful for those of us that want to be able to check all our system info (for whatever reason). That one in particular would be good for the people that only use one charger for all their devices.

Could be a program that's always running in the background, and then when a "peripheral" is plugged into any port, it tests the viability of it? It tries varying voltages on the cheap Chinese plugs...giving actual statistical feedback. Good be a beneficial program to those that have been burnt by internet buys gone wrong.

 

[Ocean112]

Wow. I'm surprised that the equivalent resistance for the charging circuit is so low that a 1 Ohm cable can lower the voltage so much. Since for a simple voltage divider circuit Vx = (Rx/Req)*Vs, 4.4v=(Rx/(1+Rx))5.0V (Assuming the resistance in your usb cable is 1 ohm.) This places your equivalent resistance for your charging circuit at only about 7.3 ohms. I had no clue the resistances in these circuits were so low. I'll have to look a bit more into this.
[doublepost=1475458528,1475457490][/doublepost]

Okay, 5.5V with 1.3A clearly provides more power than 5V with 1.3A. But why does the charger chip limit the current?

True, but then again from my understanding of things the charger chip can't limit the current. Current is a function of mostly voltage and resistance, with capacitance and inductance contributing over time. The charging chip would be able to change its equivalent resistance, like most ICs, thus changing the current. It's not a case of the charger chip limiting the current, but a case of your equivalent resistance being to high to allow for the current you need. Simple ohms law (V/R=I), right?

 

[FlapJack]

Wow. I'm surprised that the equivalent resistance for the charging circuit is so low that a 1 Ohm cable can lower the voltage so much. Since for a simple voltage divider circuit Vx = (Rx/Req)*Vs, 4.4v=(Rx/(1+Rx))5.0V (Assuming the resistance in your usb cable is 1 ohm.) This places your equivalent resistance for your charging circuit at only about 7.3 ohms. I had no clue the resistances in these circuits were so low. I'll have to look a bit more into this.
[doublepost=1475458528,1475457490][/doublepost]

True, but then again from my understanding of things the charger chip can't limit the current. Current is a function of mostly voltage and resistance, with capacitance and inductance contributing over time. The charging chip would be able to change its equivalent resistance, like most ICs, thus changing the current. It's not a case of the charger chip limiting the current, but a case of your equivalent resistance being to high to allow for the current you need. Simple ohms law (V/R=I), right?

It's obvious. The charger chip limits the appropriate volts and amps as required by the spec of the bus. It's THERE, if you care to read. It would be helpful if we knew if you were talking about USB 1.1, 2.0 or 3.0......and therein might be the problem.

 

[Ocean112]

It would be helpful if we knew if you were talking about USB 1.1, 2.0 or 3.0

It's clear that you didn't quite understand what I was saying. What USB revision I was talking about doesn't matter in the slightest. What I was saying applies to all electric circuits (at least that I know of). I made it simple and didn't account for capacitance and inductance or the rest of the network, as it would take me plugging the entire model into Altium to figure it out properly. I was only talking about the equivalent resistance of the Pyra from the USB port's Vcc and gnd which is irrelevant of the USB port itself...

 

[FlapJack]

It's clear that you didn't quite understand what I was saying. What USB revision I was talking about doesn't matter in the slightest. What I was saying applies to all electric circuits (at least that I know of). I made it simple and didn't account for capacitance and inductance or the rest of the network, as it would take me plugging the entire model into Altium to figure it out properly. I was only talking about the equivalent resistance of the Pyra from the USB port's Vcc and gnd which is irrelevant of the USB port itself...

There is no reason to be defensive. You probably know more than I do in this regard. I laid it out 5 posts ago. It's a universal program that could test all the ports and plugs(wires) into them. We're on the same team here, friend.
[doublepost=1475461970,1475460851][/doublepost]By default it can drain upto 600-700mA if charging empty battery, the current is slowly limited by the charging chip when battery charge goes up, so typically it's closer to 500mA or lower.I guess so, if the device can't provide enough current usually voltage drops, and when voltage drops below some threshold (4.5V I think) charger stops charging, which causes voltage to rise again (no more load) and charger to try charging again, which again dips the voltage, so this goes on and on, which is why you see the light flash.
[doublepost=1475462187][/doublepost]Note, that is according to the Pandora's best expert, and related to the Pandora, but we don't have space aliens making these tiny computers, we have the (relative) same team. We have electric engineers and they know their stuff.
[doublepost=1475462274][/doublepost]"I was only talking about the equivalent resistance of the Pyra from the USB port's Vcc and gnd which is irrelevant of the USB port itself".

Oh, my bad.

 

[Yoyobuae]

True, but then again from my understanding of things the charger chip can't limit the current. Current is a function of mostly voltage and resistance, with capacitance and inductance contributing over time. The charging chip would be able to change its equivalent resistance, like most ICs, thus changing the current. It's not a case of the charger chip limiting the current, but a case of your equivalent resistance being to high to allow for the current you need. Simple ohms law (V/R=I), right?

I think the charger chip just controls the current it pulls. The apparent resistance from the USB port's Vcc to Gnd is just a side effect of pulling some amount of current at some voltage.

 

[Ocean112]

The apparent resistance from the USB port's Vcc to Gnd is just a side effect of pulling some amount of current at some voltage.

HAHAHAHAHA! Oh how I wish this were true! Current is defined as dq/dt (instantaneous). It is the rate of change of charge (in Coulombs) over time. If devices could "pull" electrons on their own we probably wouldn't need a means of creating voltage and current in the first place. Lets use water as an analogy. There's a dam which feeds a river. The dam itself creates a separation in the water. It can hold back billions of gallons of water. (Your voltage source) Resistance in this case would be the gates that open to allow the water to flow from a higher potential energy state to a lower one. The flow rate is your "current" measured in this case in Litres/sec. Voltage is separation of charge, resistance is resistance to that flow of charge, and current is the flow rate of said charge.

 

[bzar]

HAHAHAHAHA! Oh how I wish this were true! Current is defined as dq/dt (instantaneous). It is the rate of change of charge (in Coulombs) over time. If devices could "pull" electrons on their own we probably wouldn't need a means of creating voltage and current in the first place. Lets use water as an analogy. There's a dam which feeds a river. The dam itself creates a separation in the water. It can hold back billions of gallons of water. (Your voltage source) Resistance in this case would be the gates that open to allow the water to flow from a higher potential energy state to a lower one. The flow rate is your "current" measured in this case in Litres/sec. Voltage is separation of charge, resistance is resistance to that flow of charge, and current is the flow rate of said charge.

I suggest reading up on how USB charging works. It's not a simple circuit. There's all kinds of sensing and negotiation going on. The host may limit the current in various ways, sometimes depending on how the device requests. Even wikipedia speaks of the device pulling current. While the terminology used above may not be strictly correct, your case only applies only at the lowest level, after all the sensing, negotiation and limiting is done.

 

[Ocean112]

First of all, please don't quote wikipedia as a valid source.

You're correct. There are few more factors to take into account, according to the whitepapers I found here and an example implementation I found here and here. But here's where we probably disagree. In essence it is still a fairly simple circuit from a high level implementation even assuming the Pyra uses a charging downstream port.

Maybe there's something I'm missing. But we're not talking about something like QC 2.0; it's just BC 1.2, right?
[doublepost=1475475929,1475474487][/doublepost]Here's another good article I found, even if it doesn't go into the details.

 

[elwing]

Very interested in this shitty cable notification feature. Other than that, I can see it being useful for those of us that want to be able to check all our system info (for whatever reason). That one in particular would be good for the people that only use one charger for all their devices.

I'm not so sure... I hate when my laptop tells me that I should use a 70W+ charger and that my currently used "dell 90W" charger is not recognized and might prevent my laptop to charge...
If that warning is only triggered when there's real instability risks, it's nice, if not it's quite bad, too much warning, notification or popup just kills it...

 

[Zink]

Does the Pyra have any means of measuring the input voltage? If so, it could warn us that we have a shitty cable.

Like this?

 

[bzar]

First of all, please don't quote wikipedia as a valid source.

I didn't. I merely used it as an example to demonstrate the common phrasing of a device "pulling" current.

On that note, though wikipedia is not by any means irrefutably accurate, it does provide a reasonable informational basis for discussion. Any qualms about its correctness can be dealt with as they arise. Though it isn't "proof" of anything, I'd count it as "supporting evidence" that can be validated or invalidated further. It has informational value as much as any other random link supporting a point of view. Much of the time it even lists references for the claims it makes, which can be further examined if the content is disputed.

You're correct. There are few more factors to take into account, according to the whitepapers I found here and an example implementation I found here and here. But here's where we probably disagree. In essence it is still a fairly simple circuit from a high level implementation even assuming the Pyra uses a charging downstream port.

Maybe there's something I'm missing. But we're not talking about something like QC 2.0; it's just BC 1.2, right?
Here's another good article I found, even if it doesn't go into the details.

As an aside, the linked article also uses the phrase "Once CDP has been established, peripheral devices are allowed to draw up to 1.5A".

I guess it depends on the definition of "fairly simple". My point is mainly that you can't just throw Ohm's law at it with some constant values and call it a day. The people above had a point in talking about the device "pulling" various currents, namely the result of the current limiting negotiation. Sure, it's the host end that does the limiting, but in the end the effect is there.

 

[Ocean112]

"Once CDP has been established, peripheral devices are allowed to draw up to 1.5A"

Spoiler

That's when the port is acting as the source of the current, not the recipient. And its not just... never-mind, forget I said anything at all.

 

[Klumpen]

we fixed it

 

[EvilDragon]

Well, don't ask me exactly how it works, but the charger chip CAN control the currency it draws.
You can set the limit to 500mA, for example, via configuration (though usually it's being negotiated via USB)

What I know is that it then tries to switch to the battery as power source.
So if the currency drawn from the USB port is reaches the limit, it grabs the rest from the battery.

It can easily mix both sources for the needed amount of power.

 

[ekianjo]

Ed does that mean that the preorder vouchers notused for purchasr were cancelled ?

 

[EvilDragon]

Preorder vouchers weren't created before the payment had been finished, so they didn't even exist yet.

 

[ekianjo]

Preorder vouchers weren't created before the payment had been finished, so they didn't even exist yet.

So if i did receive a preorder voucher from the first 200 units preorder timing it is still valid ?

 

[EvilDragon]

Of course, that's a paid voucher, why should it become invalid?

 

[shaddim]

First of all, please don't quote wikipedia as a valid source..

what da fu** ? This prejudice/FUD is still around?

Wikipedia is among the best sources around: it has good policies in place (mostly derived from the academic domain), is community/peer reviewed, is transparent about the origin of information, processes, policies and doesn't try to sell "truth" but "agreed on state of the art". Not more not less, the best possible approximation of truth. If you looking for definitive answers from authorative sources which give you "truth" .... you do it wrong.

(Sorry for this rant... but I'm quite shocked... is this a prevalent opinion? I mean Wikipedia has problems, but do we have something better? I don't see it...)