Can't launch BG95 main UART. Maybe wrong baud on some special init required?

Technical Subjects Software General Function
1

Hi,

So, I have few prototypes in test now and on devices where BG95 is used with external MCU I can’t get any reaction on main uart. BG96 on same board works well while BG95 gives nothing.
Starting on 115200 baud, using TX,RX and DTR only.
Before I will try to resolder (or solder some new boards) I would be happy to hear there are no special AT commands required on init (or maybe datasheet is wrong and default baud is different ? )

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2

Hi Grisha,
BG95 should work fine as BG96, default baudrate is 115200. Did you RDY after power up? If possible, please scope the signal on TX/RX with sending one AT command.

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3

No data from modem at all, no RDY or other. I will solder one more prototype now to check, maybe just bad luck… If will not work then will capture signals. Overall looks like TX pin of modem is not connected or is in three-state condition.

4

Found issue. BOOT_CONFIG on GNSS uart TX. After level translator there is RX pin so that is floating and looks at some point that was accepted as pull up by modem (or translator made some pull). Checking further, but feels better already

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5

Great. Thank you feedback.

6

I think this issue should be more stressed in the Hardware Design document. It should be even mentioned in the pin description, because it can be easily missed.

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Hi Grisha, what issue it is? I don’t get it but I have the same problem.

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@Cloud_Dev If you cannot communicate with BG95 and it seems as if you cannot wake it up, first thing to try is to disconnect anything from GNSS_TXD pin and restarting. If that helps then you know the problem is with this pin being pulled up during boot (which you shouldn’t).