the 120 VAC is coming from the passenger jet bridge. From there it's coming from the airport so I don't know the actual details there.

 

https://bcourses.berkeley.edu/files/66911235/download?download_frd=1 some interesting stuff.

● Contactor closure times are between 15-25 ms and opening times are between 10-20
ms.
● Essential AC buses can never be unpowered for more than 50 ms. This requirement is
necessary in order for contactor switches to open or close to avoid paralleling of
sources. DC buses shall never be unpowered under no fault conditions.

This is "in the aircraft". No mention of external interfaces.

The laptop charger may be better able to ride through the event.

 

That’s helpful. Somewhere in there though either the VBus drops to kill enumeration or the iPad lightning logic (NXP203s??) thinks there is a potential threat.

Either way I know some planes with newer gen control units don’t do any of this.

The re-plugging of the cable (or waiting until there are no more transfers to plug in) will most likely be the decision.


The older planes have an issue with transfers that can interrupt steering controls on the ground. As a result those controls must be neutral before bringing another generator online. As parts are replaced they get the newer ones with faster times. My guess is these older ones are what’s affecting the USB times.

 

I noticed something else I had not tried in earlier observations:

During a power transfer, when the Suspend state is reached between the TIM and the iPad you cannot simply turn off the TIM and re-power it. Doing so went to a 5V & 400 milliamps.

The powered state of the USB is simply 100 milliamps, which is what I get after the transfer (actually it's only pulling about 80).

However, 500 mA is the max for a standard downstream port, and I'm again getting shy of that @ 400 mA. SDP is if the bus is not suspended and configured.

So, after the transfer:

0. it enters the 'powered' state (max 100 mA and pulling only 80); but
1. resetting the TIM power puts it into a SDP mode (max 500 mA) and pulling about 400); and
2. pulling the lightning from the iPad and doing a re-plug gets it back to a CDP mode (charging downstream port) with the 1.5A needed for charging.

I just found it entertaining that re-setting the lightning handled enumeration, but re-setting the power button on the TIM did not.

So there is something going on with the Vbus rising edge that it does in fact need; and staying connected doesn't return the D+/D- to their pulled up or down states?

I wonder if this has something to do with the [E75 & NX20P3] ICs in the lighting cable and the Tristar in the iPad. They need to drop off completely to begin their handshakes as well as enumeration?


Since I know the powers that be will lean toward just doing a lightning re-plug, I wanted to make sure that resetting the TIM would or wouldn't work in the event someone just decides to toggle that thing off and on.

Tomorrow morning (since I forgot) I'll try pulling the USB from the TIM instead of the lightning to see what results it gets.

BTW, the USB IF BC specs book is a real, I mean a REAL, page-turner.

 

https://www.beyondlogic.org/usbnutshell/usb2.shtml

#1. Make sure you try an decent amount of off time like 30s.

If VBUS is lost, the device has a lengthy 10 seconds to remove power from the D+/D- pull-up resistors used for speed identification.

I just found it entertaining that re-setting the lightning handled enumeration, but re-setting the power button on the TIM did not.

So there is something going on with the Vbus rising edge that it does in fact need; and staying connected doesn't return the D+/D- to their pulled up or down states?

When reading "something" about USB, I remember something about where the pull-ups can be removed by the IC. Doubt I can find it again, but it looks like I did.

Your USB meter, looks like it can interact.

Suspend mode is mandatory on all devices. During suspend, additional constrains come into force. The maximum suspend current is proportional to the unit load. For a 1 unit load device (default) the maximum suspend current is 500uA. This includes current from the pull up resistors on the bus. At the hub, both D- and D+ have pull down resistors of 15K ohms. For the purposes of power consumption, the pull down resistor at the device is in series with the 1.5K ohms pull up, making a total load of 16.5K ohms on a VTERM of typically 3.3v. Therefore this resistor sinks 200uA before we even start.

 

https://www.beyondlogic.org/usbnutshell/usb2.shtml

#1. Make sure you try an decent amount of off time like 30s.

If VBUS is lost, the device has a lengthy 10 seconds to remove power from the D+/D- pull-up resistors used for speed identification.



When reading "something" about USB, I remember something about where the pull-ups can be removed by the IC. Doubt I can find it again, but it looks like I did.

Your USB meter, looks like it can interact.

Yeah I reset the TIM power and it would go to connected (100mA) almost right away, then SDP (500mA) at 10 seconds, and finally DCP (or apple charging) at about 20-22 seconds.

Interesting.

That’s good though. Re-plug can be done on either end it seems or by resetting the TIM

 

That’s good though. Re-plug can be done on either end it seems or by resetting the TIM

So, you don;t have to wait an extraordinary amount of time at off?

This https://www.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00004193.pdf article is interesting.

One of the USB Compliance Checklist for Peripherals items asks the following question:
“Is the device’s pull-up active only when VBUS is high?”.

it might be worthwhile to monitor D+ to ground after a transfer?

This http://www.techunboxed.com/2013/06/usb.html would be useful. You can order the board. The components have to be ordered separately from the BOM. Bill of Materials.


You would need a short AB cable like: https://www.superwarehouse.com/Belk..._A_to_4_Pin_Type_B,_6_/F3U133-06INCH/p/484968

I think it also means that you could easily breadboard the "reset" circuit I suggested earlier.

The breakout adapter by itself, should also work, just by removing the VBUS jumper and re-inserting the jumper.

If that works, there is a excellent possibility that the reset gizmo would work.

Prove that and then try to get the MFR of the TIM to make the appropriate changes.

 

So, you don;t have to wait an extraordinary amount of time at off?

This https://www.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00004193.pdf article is interesting.

One of the USB Compliance Checklist for Peripherals items asks the following question:
“Is the device’s pull-up active only when VBUS is high?”.

it might be worthwhile to monitor D+ to ground after a transfer?

This http://www.techunboxed.com/2013/06/usb.html would be useful. You can order the board. The components have to be ordered separately from the BOM. Bill of Materials.


You would need a short AB cable like: https://www.superwarehouse.com/Belk..._A_to_4_Pin_Type_B,_6_/F3U133-06INCH/p/484968

I think it also means that you could easily breadboard the "reset" circuit I suggested earlier.

The breakout adapter by itself, should also work, just by removing the VBUS jumper and re-inserting the jumper.

If that works, there is a excellent possibility that the reset gizmo would work.

Prove that and then try to get the MFR of the TIM to make the appropriate changes.

That’s neat. I’ll see if I can get approval to keep testing it.

On a side note:


If you had to choose between resetting the lightning cable at the iPad or resetting the usb-a tip in the TIM charger, is there a preference?

Safety?

They seem the same at this point as far as signals are concerned.

 

I'd pick the power switch on the TIM.

Any cable is going to break. https://discussions.apple.com/thread/6185323 So do USB ports. They have a giant Lever arm on them. My laptop likes to fall on the plugged in cable which means a bad port on the laptop.

Socket savers exist: http://www.l-com.com/usb-usb-20-type-a-and-b-socket-savers but that just makes the lever arm longer.

I did have a Microsoft wireless mouse that kept breaking the base. I used this http://www.l-com.com/surge-protecto...pe-a-type-a-panel-mount-style-with-pigtail-12 surge suppressor to stop it. It just depends how the stuff is designed. The pigtail cable can also act as a socket saver too, but it's probably as expensive as a lightning cable.

With constant plugging, something is going to break. I've had USB cables break.

You have mating cycles. This https://www.iconnsystems.com/blog/connector-mating-cycles mentions USB and you have the flexing of the cord at the ends.

Litz wire https://www.coonerwire.com/litz-wire/ is probably the most flexible. Old telephone station wire was really flexible too. It was a flat multi-strand wire spirally wrapped around a core.

So, the wires break at the ends.

It might make sense to have a means of detecting cable faults. A lightning breakout is here: https://www.ebay.com/i/381376155289 . You can find ones for USB. So, you can wire something together with a bunch of LEDs, adapter or whatever so you can flex and test the cables or maybe adopt a replacement interval or keep a spare cord handy.

 

I'd pick the power switch on the TIM.

Any cable is going to break. https://discussions.apple.com/thread/6185323 So do USB ports. They have a giant Lever arm on them. My laptop likes to fall on the plugged in cable which means a bad port on the laptop.

Socket savers exist: http://www.l-com.com/usb-usb-20-type-a-and-b-socket-savers but that just makes the lever arm longer.

I did have a Microsoft wireless mouse that kept breaking the base. I used this http://www.l-com.com/surge-protecto...pe-a-type-a-panel-mount-style-with-pigtail-12 surge suppressor to stop it. It just depends how the stuff is designed. The pigtail cable can also act as a socket saver too, but it's probably as expensive as a lightning cable.

With constant plugging, something is going to break. I've had USB cables break.

You have mating cycles. This https://www.iconnsystems.com/blog/connector-mating-cycles mentions USB and you have the flexing of the cord at the ends.

Litz wire https://www.coonerwire.com/litz-wire/ is probably the most flexible. Old telephone station wire was really flexible too. It was a flat multi-strand wire spirally wrapped around a core.

So, the wires break at the ends.

It might make sense to have a means of detecting cable faults. A lightning breakout is here: https://www.ebay.com/i/381376155289 . You can find ones for USB. So, you can wire something together with a bunch of LEDs, adapter or whatever so you can flex and test the cables or maybe adopt a replacement interval or keep a spare cord handy.

Well the good news is plugging the iPad to the TIM isn’t even mandatory so long as the iPad has a specific charge prior to starting the trip. So, you could go a day without touching one. I had never heard of mating cycles.

Amazing.

 

When it comes to contacts, some can be rated for AC or DC or both. You have switching and carrying currents. Had a relay that was rated at 30 kV at say 3A, but you had to switch at 0 Amps.

There is something called wetting current and that's the minimum current it can switch. The gray area is 1-10 mA. Some contacts develop an oxide and the wetting current assures removal of the oxide, otherwise you have to revert to exotic materials.

Your project is actually interesting.