I wrote a MATLAB program that communicates with an ESP32 via Bluetooth to transfer files (between .5kB and 4kB) from the ESP32 to the host computer. It works most of the time, but every 20 to 80 files on average, it hangs up, and I can't get Bluetooth working again, unless I completely close and re-opent MATLAB.
I create the connetion like this...
bt = bluetooth("ESP32", 1)
Then I write an 'R', which tells my ESP32 to begin sending the next file
write(bt,'R')
Then I read back the data in MATLAB. I know the file size beforehand, and I'm 99% certain that the ESP32 is sending back the correct number of bytes.
bluetooth_response = read(bt, fileSize);
I loop through the write and read several and it works most of the time, but every 50 files or so, it's not able to read in the expected amount of data, and I get this warning.
Warning: The specified amount of data was not returned within the Timeout period for 'read'.
Once this happens, all subsequent reads return 0 bytes. And the funciton NumBytesAvailable returns 0. However, I can verify on the ESP32 side that it is still get the 'R' commands from MATLAB and it is reporting that it is sending the appropriate number of bytes.
numBytes = bt.NumBytesAvailable; (always returns 0 after read warning occurs)
After this happens, the only way I found to get Bluetooth working again is to completely close and re-open MATLAB. I thought maybe the ESP32 was sending data back too quickly and overwhelming the buffer, so I slowed it down (to about 1000 bytes/sec ) and that didn't help. It seemed to help a little bit if I turned off my Bluetooth mouse during the transfer, but that was inconclusive, because the frequency of incidence is too random to say for certain that it helped.
Any ideas what could be causing this problem?
