NEW Brymen Bluetooth BM787BT Multimeter

[joeqsmith]

Just checked and the new software is now available.   Looks like they have not yet appended my notes on programming the FLASH.   

I'll setup a few tests later today.  Hoping they now stream that data.  Last time I ran it, I once again lost all of my data.   

[joeqsmith]

Appears the new cell phone application can download the programming files.  The first time I tried it, it failed.  The second attempt, it downloaded the file and updated the meter correctly. 

There is no change log, so I really have no idea what was changed.  I can tell you that when I started the log, it still does not ask for a file.  They continue to try and collect the data in RAM rather than steaming it to NVRAM.   I'll let it run overnight and see if I can get it to save the data without loosing it.     

[joeqsmith]

Batteries failed in the one meter over night causing a disconnect. Oddly enough, the software actually saved the data.     I went ahead and installed a fresh set of AAs into my hacked battery holder.   Time for some extended testing.   The other meter/phone continues to run.  Odd, when I restarted the second meter I noticed that the other phone has not slowed down at all.  After 12 hours, I would normally notice it.   

I'll continue letting these run for the remainder of the week and report back, but it does appear they have made some improvements.

[joeqsmith]

Funny, just noticed Brymen provide me with a change log for their latest software.  It appears they have addressed all my concerns.  I'll post an update at the end of the week.  If I don't loose any data, that's going to be a huge deal!!

Graphic Display Smoothness
Improved UI performance by displaying one page at a time without retrospective rendering to prevent overload. The application's sampling rate remains unchanged, even during extended logging periods.

BLE Connection Stability
Resolved an issue with BLE disconnections by debugging a low-level infinite loop in the BLE communication layer.

Reconnection Reliability
Improved reconnection behavior by addressing the same low-level BLE loop issue as above.

Real-Time Logging and Data Saving
Each reading is now written directly to the database immediately upon receipt from the meter, without using RAM buffering. This enhances both performance and reliability.

Data Loss Prevention
As readings are saved directly to the database file in real time, data remains intact even if the phone powers off unexpectedly during logging. Data loss is effectively
prevented.

Data Saving Completion
Data saving now completes automatically once logging ends. No additional processing is required afterward.

CSV File Format Consistency
Improved consistency in the CSV data file format for better compatibility and ease of use.

[EEVblog]

Funny, just noticed Brymen provide me with a change log for their latest software.  It appears they have addressed all my concerns.  I'll post an update at the end of the week.  If I don't loose any data, that's going to be a huge deal!!

Graphic Display Smoothness
Improved UI performance by displaying one page at a time without retrospective rendering to prevent overload. The application's sampling rate remains unchanged, even during extended logging periods.

BLE Connection Stability
Resolved an issue with BLE disconnections by debugging a low-level infinite loop in the BLE communication layer.

Reconnection Reliability
Improved reconnection behavior by addressing the same low-level BLE loop issue as above.

Real-Time Logging and Data Saving
Each reading is now written directly to the database immediately upon receipt from the meter, without using RAM buffering. This enhances both performance and reliability.

Data Loss Prevention
As readings are saved directly to the database file in real time, data remains intact even if the phone powers off unexpectedly during logging. Data loss is effectively
prevented.

Data Saving Completion
Data saving now completes automatically once logging ends. No additional processing is required afterward.

CSV File Format Consistency
Improved consistency in the CSV data file format for better compatibility and ease of use.

Those are huge updates, will try it today.

[EEVblog]

My android app is now 1.0.70 but it no longer connects at all.
The apple app hasn't updated from 1.0.64 yet, but it still connects within seconds.
Something is up...

[joeqsmith]

My android app is now 1.0.70 but it no longer connects at all.
The apple app hasn't updated from 1.0.64 yet, but it still connects within seconds.
Something is up...

Were you able to update your meter to the latest firmware for both the radio and meter first?  Does the app detect the meter advertising?  Does it hang during the connection phase (where you see the %)?   

I am testing with the Motorola and BLU phones as these were the most problematic in the past.  Both meters have the latest updates.  Both phones should also have the latest Android updates.   I've not had any problems connecting.   

***
If you are not able to update the firmware following my previous instructions, at what step did you run into problems? 

Also, if you provide the current firmware revisions, I may be able to downgrade my meter and see if I can replicate what you are seeing and maybe find a work around for updating yours. 

[joeqsmith]

Brymen has provided details on how their application obtains the CYACD files.   I plan to add this to my custom software.   I tried a quick test from where I work but FortiGuard blocks them.  One advantage to using your own cell phone provider over a corporate LAN. 

[joeqsmith]

1)Application's sample rate slows down while logging for extended periods *3
2)Phone drops connection at random (not battery, low signal or outside RF interference)
3)Unable to reconnect after a connection was made (requires restarting the application) *3
4)Recorded data is 10x higher than actual and outside of meters range *1
5)If phone powers off due to low battery, data is lost *2
6)Application hangs when trying to save data *3
7)Cell phone data file format (units after value) is inconsistent in different functions/ranges *3
Cell phone will not connect to DMM

*1 Fixed as of 7/11/25
*2 I am not sure why they don't ask for the file name first, then stream it to NVRAM rather than keeping the data in RAM
*3 Fixed as of 9/8/25

One feature I have asked them for is a way to flush the database.  During this extended testing, I have ran into various problems but I had no data loss!!!   

While I am not sure what version of firmware is in Dave's meter,  it appears that while my Motorola and BLU phones connect, the UNNECTO no longer will.  During the scan process, it never sees the DMM advertising.   I have made Brymen aware of this.

Brymen was also able to replicate problem #2.   They believe that notifications and not being received and this seems to be what I am seeing as well when running my custom application. 

I have added support to my software to download the CYACD files from their site.  Works like a charm.  Because corporations may block this service, Brymen will provide a direct link allowing customers to manually download the files.   

[joeqsmith]

Brymen had asked about using WireShark to see what was going on at the time the phone stops logging.   This was the first time I have ever attempted to run WireShark with that NORDIC radio for an extended time.   WireShark allows you to run in a mode where the display is not updated to ease the burden but because it can be a bit hit and miss getting it to track the meter, I keep the display active to monitor the traffic.

Surprisingly, it actually collected the entire set of data, from advertising, to logging on and sending the password, till the phone stopped updating.   Luckly, it didn't take long.  About 15 hours of data.   At 5Hz, that's not too bad.  260,000 samples.  But consider that BLE is actually sending data much faster.  We end up with 3,616,815 packets.  Most of them empty.   That's a lot of data for WireShark to crunch but it worked!   

I have sent everything to Brymen.   Hopefully they are able to solve why Dave's phone along with my UNNECTO will no longer connect, along with this one last problem.   I think once those two are solved, the rest is just fluff. 

[joeqsmith]

One feature I have asked them for is a way to flush the database. 

   Brymen explained how once you select "files", you can slide each log file to the right.  It will then prompt you if you want to delete it.   I tried it and it works great.  I'm sure the kids would have figured this out in seconds! 

[joeqsmith]

Brymen tested their UNNECTO Bolt 10 and had no problems connecting.   I tried mine again, letting it sit in the scan mode for at least a minute, and it would not detect the meter.   Looking a second time at the phone settings, BLE is enabled.  This time I toggled it off and on.  Sure enough, the phone starts seeing the meter and connects to it.   

I'm not impressed with these cell phones and don't see the attraction for using them with test equipment as they seem so unpredictable.  That's not Brymen's problem.

So the only major problem is just the meters appearing to randomly stop sending notifications.   I looked at the log files today and I have several that ran for over three days.  Normally the meter appears to hang before 24 hours.  I was not taking notes as to why each stopped logging.  Meter and phone battery life was certainly a problem and why I hacked up that 3X AA battery pack.  I have asked Brymen to supply me with the older firmware so I can attempt to track down when this problem showed up. 

My software tracks the time between notifications and plotting this data, there was a change between 1.0.1 and 1.0.2 that looks like they tried to improve the transfer speed as the last two revisions are more stable.   
***
spelling

[EEVblog]

Brymen are sending me a new bluetooth module with the new version, should arrive monday.

New apple app seems to work great.

[joeqsmith]

When you get the new radio, if the Android phone will still not connect, try the following:

If the phone doesn't see the meter during the scanning process, cycle the BLE radio off/on.  If that doesn't work cycle the phone's BLE radio in the utility menu.

If the phone sees the meter but will not link,  on the Devices menu, highlight the BM78xBT.  Select the three vertical dots to the right of the Setting.   Select Remove the device, and try to reconnect.   

[EEVblog]

iPhone app does not create blank (NaN) time stamped reading when you walk out of the bluetooth range, I'm pretty sure it used to do that?
What is does now is it just pauses the live graph continues with the next 0.2sec timestamp as if nothing happened once the packets start coming in again. So you end up with a distorted waveform rather than a waveform with missing data as a true time stamped data logger graph would show.
This means you have to make sure you have to plot the X axis based on the actual time stamp, which is correct.

[joeqsmith]

iPhone app does not create blank (NaN) time stamped reading when you walk out of the bluetooth range, I'm pretty sure it used to do that?

From my experience the first version would blank the screen and loose all the data. 

[EEVblog]

New BLE module installed.
Didn't work at first, needed to add a new meter. I think that was the problem before on the android when the app was updated.

[joeqsmith]

Video is misleading stating all known problems have been corrected.

It appears that the meter will stop sending notifications after some random amount of time.  While logging with the phone application, the graph will stop updating.  This is the last major problem I am aware of and Brymen is working on it.   This is a problem with the meter's firmware, not the phone's application.    I expect there to be a 1.0.4 soon, or they may try to do something similar to work around it in software like I did with Windows.   

If you had left the other radio in the list and plug the other radio back in, the software may not scan through the known addresses to find the other radio.  I've tried this with two meters sitting side by side with the phone.   I think there is a problem but guessing very few people will run into it which is why it never made my list.

[EEVblog]

It appears that the meter will stop sending notifications after some random amount of time.  While logging with the phone application, the graph will stop updating. 

I've never seen that.
Having said that I had it logging all day today on the iPhone and only just now did the waveform freeze. Went to check the meter and it was turned off for some reason. Doesn't seem to be low battery. I simply turned the meter back on, turned data back on the the app just resumed logging.

[joeqsmith]

Today, Brymen provided 1.0.4 to address that problem.  I plan to set it up with the latest application and will let it run for the remainder of the week.   


I frequently saw where after the meter powered off, when I turned it back on it shows good battery.  The meter would  shut back off shortly after BLE was re-enabled.   There is a reason I cobbled up that 3XAA battery pack for these longer tests.   If you plan to run a long term test, it is best you start with a fresh set to avoid loosing that data.  I think the meter had to run continuously to observe that fault.     

***
Also, you should now be able to update yours using the OTA feature of the phone once they make that firmware available to the public (currently not available). 
***
Updated both meters, using my custom software.  No problems there.  Went to update the phone applications and batteries were dead.   I think the phones wake up from time to time.  I will have them stacked on top of one another on the bench and three times now I have found them on the floor.  Like the vibrators turn on for the fun of it...       Was able to get them charged enough to turn on and update the application.   These tests are long enough that I have to leave them plugged in for the duration anyway.    Trying the new economy mode that Dave shows.  Supposed to consume less power.   This may help as I have had the phones run out of power before on these long tests, even when plugged into their chargers.       

[joeqsmith]

Both setups have been collecting data for 26 hours now without seeing the notification fault.   Typically one of them would have failed by now, so my confidence is growing in these latest updates. 

[EEVblog]

It appears that the meter will stop sending notifications after some random amount of time.  While logging with the phone application, the graph will stop updating. 

I've never seen that.
Having said that I had it logging all day today on the iPhone and only just now did the waveform freeze. Went to check the meter and it was turned off for some reason. Doesn't seem to be low battery. I simply turned the meter back on, turned data back on the the app just resumed logging.

Correction, it was the battery. The Bluetooth transmit pulses can cause a low battery event and hence meter shutdown in data logging mode, without registering low battery in non-logging mode. Not surprising when you have  rising battery ESR at end of life.

[EEVblog]

I frequently saw where after the meter powered off, when I turned it back on it shows good battery.  The meter would  shut back off shortly after BLE was re-enabled.   There is a reason I cobbled up that 3XAA battery pack for these longer tests.   If you plan to run a long term test, it is best you start with a fresh set to avoid loosing that data.  I think the meter had to run continuously to observe that fault.

Explains why I have never seen it. All my tests have been within the time limits of the standard battery pack.
I wouldn't be concerned about such an issue at all, as this isn't designed as a really long term data logger solution.

[joeqsmith]

I've seen it with a new set of batteries loaded in the standard pack.   I think the shortest time I had it run and saw the notification fault was maybe 5 hours.    Typical was maybe 24 hours.   The last time when I used WireShark to log it, was 15 hours. 

Currently at 36 hours run time, no fault.  It's looking really good.   

[EEVblog]

I've seen it with a new set of batteries loaded in the standard pack.   I think the shortest time I had it run and saw the notification fault was maybe 5 hours.    Typical was maybe 24 hours.   The last time when I used WireShark to log it, was 15 hours. 
Currently at 36 hours run time, no fault.  It's looking really good.   

They specifically said it's a fix, so they must have found the bug.

Our BLE firmware has already the update version V1.0.4. For long time logging, we found the connection may hang occasionally. After further analyzing, we found it was caused by BLE Notification channel. It stops outputting Reading Packets while BLE Command Write/Read channel still works. This update version is to fix this problem.

I'm trying to update mine it to the new version, but my meter refused to connect any more. Resetting password didn't work, I had to remove the device and reconnect.