Cellular module & a couple power questions

Archive
1

On the product page for the Cellular module has this note:

  • So when debugging my project would I use both USB and external power? (Have a plugin wall wart for it).

For battery power, when not at a receptacle, I was thinking of using a 6xAA holder and rechargeables.

  • Would this provide ample power for the cell, other modules and a Spider?

To determine the approx run-time:

  • Would I use meter to get the amperage at the battery, and then divide that from the mAh of one of the batteries?

Thanks

2

Yes

[quote]For battery power, when not at a receptacle, I was thinking of using a 6xAA holder and rechargeables.

  • Would this provide ample power for the cell, other modules and a Spider?
    To determine the approx run-time:
  • Would I use meter to get the amperage at the battery, and then divide that from the mAh of one of the batteries?
    [/quote]

You will draw about 400mA I think when you have both.

3

You will draw about 400mA I think when you have both.
[/quote]

Thanks Gus – I’ll actually have a little more than plugged in :slight_smile:

**

If my Gadgeteer is plugged into a vehicle and use 12V to USB adapter, would that be ample to power both? Or would you suggest something that would take the 12V and clean it up and then still use the plug?

4

I think you can use the USB Client DP module directly with a car battery.

5

I would expect that the current for a “standard” car 12v-to-USB adapter will NOT be sufficient. The USB spec says 500ma, but many converters I’ve seen are stable below 400ma and that last little bit is what usually brings devices unstuck if a device draws more current, as the voltage drops rapidly. As Gus says, try to let the DP module handle this problem, or only down-shift to say 7v but with something like a 1000ma capable circuit.

6

@ Gus - I have a FEZ Spider with Cellular Phone, GPS, T_35 screen and have connected to the power plug of the USB_ClientDP module a 7.4V Li-Ion battery. The board started regularly but after few minutes the USB module started to get warm and finally the red LED on the USB board and on the cellular phone blinked. End results: my Spider board is now not working anymore. Are you really sure that one can power these boards from a battery through the USB_ClientDP board??

The set worked correctly from the computer with the USB connection only.

7

Blinking means protection kicked in. This also means you exceeded the allowed 800ma.

We are planning a high current module. I guess now we need to hurry up and finish it.

8

@ Gus - But why is now my FEZ Spider dead? It has probably a short since the USBClientDP blinks and the red LED on Spider is not on

Thanks for your quick reply

9

What you did should not cause any damage! Disconnect all and only use spider. And try power module alone.

10

@ Gus - I disconnected already everything, but it is dead. The USBClientDP alone works with another board and provides 5V and 3.3V correctly.

11

I can’t think of any reason on why this could have happened!

By saying dead, what do you mean? Does the LED on spider board light up? What do you see on USB?

12

@ Gus - LED on USBClientDP is blinking, no LED on Spider. The tensions on Pin 1 and 2 are correct (3.3V and 5V) when no Spider is attached. When the Spider board is attached, they are approximately 0-0.2 V. If I try to upload my program, it is not possible and I get following message

Deploy started: Project: GadgeteerApp1, Configuration: Debug Any CPU ------
Device not found or cannot be opened - USB:Gadgeteer========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========
========== Deploy: 0 succeeded, 1 failed, 0 skipped ==========

13

Time to contact GHI directly for RMA.