uFL GPS Antenna mod


#1

Anyone have any info/whitepaper for populating the uFL pads on the GPS antenna? Specifically what value inductor should be used to enable this connection?

Thanks


#2

You will need to populate the U.FL connector at J11. This is Molex part number 0734120110 available from Digikey.

next you need to disconnect the onboard antenna and connect the U.FL connector to the circuit. Here you have two options on how to do it. 1) for a non-powered antenna, remove R126 (zero ohms) and short the pads at C217. 2) for a powered antenna you will need to install a 22pF capacitor at C216.

R126 and C216 share a common pad and are placed at right angles to each other so only one of the two can be populated at any given time.

The inductor (L19) should be 100nH and the capacitor (C217) should be 1uF. C217 is a filter capacitor. These two components provide power to your active GPS antenna. If you are not using an active antenna (no internal amplifier) then you don’t need these components installed. Not all powered GPS antennas will run from 1.8V make sure you select one that does. Also check that the SW turns on regulator L4 at 1.8V to power an active antenna.

It should be noted that I haven’t tried this out so I am not sure it will work!. Good Luck.

Full Disclosure: I am an employee of Qualcomm Canada and any opinions I may have left in any post do not necessarily match the opinions of my employer.


#3

Wow thanks for the research/info!


#4

oops, I made a typo up above. option 1) (non-powered antenna) you should short C216, not C217.


#5

Hey,
@ljking
I’m using Taoglas AP.25E.07.0054/ 5v antenna and I have capacitors at R216 and inductor at L-19 but don’t have a capacitor at which has to be placed at C217.
Should the antenna work properly without that capacitor if I install active antenna?


#6

Hi @nageshkar

C217 is not that important, particularly if you are using a 5V antenna. Because you are using a 5V antenna you need to stand L19 on end on the pad that connects to the U.FL connector. From the top of L19 you need to run a jumper wire to a 5V supply.

Full Disclosure: I am currently an employee of Qualcomm Canada and any opinions I may have left in any post do not necessarily match the opinions of my employer. As of May 22nd/2018 I will no longer be employed by Qualcomm Canada. Currently looking for new opportunities, you can contact my personal email through the forums at 96Boards.


#7

Hey,
Do you mean I have to soulder the wire on L-19 whose one end connected to 5 v supply at low speed expansion slots?


#8

Hi @nageshkar

Yes correct, the wire will go from the top of the inductor to the 5V supply somewhere on the board. The 5V supply is eay to find at the low-speed connector.

Full Disclosure: I am currently an employee of Qualcomm Canada and any opinions I may have left in this or any other post do not necessarily match the opinions of my employer. As of May 22nd/2018 I will no longer be employed by Qualcomm Canada. Currently looking for new opportunities, you can contact my personal email through the forums at 96Boards.


#9

Hey,
@ljking, @danielt, @Loic
As per guidelines given in the release note for adding active GPS antenna, I soldered component at
L-19, C-216 and removed R-126 with component given in the note. As above discussed i am using 5v taoglas GPS active antenna and i soldered wire from 5 V power supply from low speed expansion connector.The soldering work is done by professionals.
After the rework when I switched on the board the bluetooth LED glown for moment and board is not working now.
when I checked the power supply with multi-meter at J-1 it is showing 12 v supply at J-1 and at 5V supply at low speed expansion connector there also I am getting power 5V. Same with both USB ports and HDMI port.
But when I am connecting board to HDMI monitor it showing “No HDMI connection”. And i tried to connect it with Wi-Fi it also not gettiing connected. and everytime i give power to board bluetooth LED is glowing for a moment.
can you please tell what would have happened with board?
Thanks in advance.


#10

I’m afraid it sounds like it might be broken.

However you should certainly try one of the board recovery approaches:

Do you have a serial adaptor for the board? The main clues to what might be broken would probably come out via the serial port.


#11

Hey,
Thanks for replying @danielt.
I gone through the recovery methods but for that also I need to access HDMI monitor for visuals. But when I am giving power to dragon board it is not showing anything on screen.
I didn’t got the serial adaptor method, Do you mean via UART ports?
can you please explain recovery methods which I can perform without HDMI monitors?


#12

If you have attempted the SD card recovery method and even the heartbeat LED doesn’t work then this is pretty clear evidence that your board is broken (i.e. we can be fairly confident we are looking a physical damage rather than “bad luck” with software).

I’d also note that the (admitedly less robust) fastboot method doesn’t require HDMI monitor.

Serial adaptor is not a method, it is merely that there might be clues about what has been broken coming out of the UART.


#13

Before writing the board off, first try undoing the modifications made to it.


#14

I agree with @doitright, before writing off the board undo the mods. However the most likely error was standing the inductor on the wrong pad. If you did this then 5V supply was applied to the 1.8V rail on the board and would have caused at least part of the PMIC to fail if not more…

Full Disclosure: I am currently an employee of Qualcomm Canada and any opinions I may have left in this or any other post do not necessarily match the opinions of my employer. As of May 22nd/2018 I will no longer be employed by Qualcomm Canada. Currently looking for new opportunities, you can contact my personal email through the forums at 96Boards.


#15

Hey,
I tried with fastboot method but it is not showing my board in fastboot devices.
even i tried by removing the modifications but still it is not working.
when I power on board only bluetooth LED is blinking for moment and then it not showing anything on screen.
is there any recovery center or service center where I can check what is the problem?
Can you tell me other methods by which I can recover my board?


#16

I’m afraid I’m not aware of any kind of service centre.

Having undone the mod and attempted both software recovery methods I don’t think there is much more you can do. If you have a 1.8v UART you could check for clues on LS-UART1 but it might not add anything new (there could be no output).


#17

And on top of that, considering the price of these boards, I doubt that you would save any money by fixing it. Perhaps one of the more expensive boards (hikey 960/970, db820), but db410 just means no morning coffee for a couple of weeks.


#18

And on top of that, considering the price of these boards, I doubt
that you would save any money by fixing it. Perhaps one of the more
expensive boards (hikey 960/970, db820), but db410 just means no
morning coffee for a couple of weeks.

That might depend where you are in the world, what the import duty is,
and what the local market is like for repair services (these are
related, very high duty tends to stimulate the market for repair
services).

However I agree, for me in the UK, repairing a DB410C is unlikely to be
economically viable.