First batch received, but need some troubleshooting assistance

[tremmert81]

Hello,
We just received our first batch of SnapperGPS units and need some assistance...

1. I successfully flashed the latest firmware

2. When I plug the device into the computer, I can configure the device to start recording immediately every 20 second.

3. Battery voltage is showing 4.17v

4. When I disconnect the Snapper from the computer, the green LED flashes several times.

5. I leave the unit alone for 1 hour.

6. Disconnect the battery

7. Plug the device back into the computer, but it shows zero snapshots.

Any thoughts? GPS antenna is connected and the device is outside.

[JonasBchrt]

• Does the green LED flashes (very briefly) every 20 s during recording? (That would be desired.) Or do both LEDs flash occasionally? (That would not be desired because it means that the receiver hasn't started recording yet.) Or is none of the LEDs flashing during the recording? (That would mean that the device turned off.)
• If the second option holds true, then double-check that you configured start and end time for the recording on the configuration page correctly. (Or unchecked one or both options.)

[tremmert81]

snapper.bin.zip This is the same as the normal firmware, except that it does not check the HF oscillator frequency. If you want, you can try it, and it might allow you to record data and read it back via USB. However, with a likely non-functional oscillator, the recorded data would probably just be random noise rather than actual satellite signals.

I tested this new firmware, and the device seems to behaving exactly the same as before. In other words, I configure the unit, disconnect the unit, then it blinks a few times but that is all. When I plug it back into the laptop, it is NOT detected. I must disconnect the battery, then re-connect the USB cable.

[tremmert81]

The function that measures the frequency of the HF oscillators is pretty short. It has a single while loop where it waits for the oscillator frequency being calibrated/measured. Basically, it "counts" the frequency of the HF oscillator w.r.t. to the frequency of the LF oscillator and this while loop waits until the counting is complete. If this does not happen, that suggests that something is wrong with one of the oscillators, most likely with the HF one, i.e., the one with 16.384 MHz.

The BOM offers three options for this oscillator, the Connor Winfield D32G-016.368M, the EPSON X1G005441030112, and the TXC Corporation 7Q-16.368MBG-T. Which one did you use?

The D32G is a bit more challenging to orientate correctly because the dot that indicates pin 1 is very faint according to my experience. Can you have a look at the picture below and check whether the faint dot on top of the IC is at the corner that is indicated by the red arrow? Sometimes it is easier to check the part orientation by looking at the text rather than the dot. There should be 2 lines of text on the D32G, one in the middle and one at the bottom on the side towards the 4150L radio IC, but there should not be a line of text at the top next to the battery connector. I tried to shoot a photo that shows this, but failed...

Regarding the oscillator, we selected the Connor Winfield D32G-016.368M. I have been trying to take a photo to identify pin 1, but am unable to get a 100% confident picture.

I have reviewed 5 different boards, and they all seem to have a darker spot. From the data sheet, I assumed the pin 1 dot would be closer to the edge of the chip. Tomorrow I will ask around to see if I can find a microscope to get a better image of the chip.

[JonasBchrt]

I'm pretty sure that I can see the pin-1 dot on your photo at the corner of the IC that is indicated by your red arrow. That would mean that is mounted the wrong way. The files on GitHub show that pin 1 with the dot shall be on the opposite corner. Closer to the PCB edge.

[JonasBchrt]

Here is a board with the dot in the correct corner.

[JonasBchrt]

Just curious, any updates regarding this @tremmert81 ?

[tremmert81]

First off, thank you for your help. You did identify and correct our issue. I watched a few videos on using a SMD heat gun and was able to flip the IC. The boards are working perfectly now.

Looking forward to some successful deployments!