Bluetooth BLE - problems when transmitting and receiving long strings

MIT App Inventor Help
1

Good morning,
with Mit App Inventor I created an App that every second send this string of 260 lowercase ASCII characters in packets of 20 bytes over Bluetooth BLE to a custom STM32 board with an HM-11

"abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz\n"

The same App and receives this string of 260 uppercase ASCII characters every second from the STM32 board, always in 20-byte packets

"ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ\n"

The two transmissions are NOT synchronous, APP and STM32 transmit with their own time base. Both programs check the received string and save any errors. What I notice that every 1-2 minutes a packet of 20 lowercase characters sent by the APP I find it in the message received:

"ABCDEFGHIJKLMNOPQRSTabcdefghijklmnopqrstOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ"

I add that:

  • the messages received by the STM32 card are all correct
  • if the APP does not transmit anything, all the received packets are correct

Thanks and sorry for my english
Mario

2

Packets are transmitted every 0.5S and NOT every 1S. With transmission times of 1 second the problem does not occur. Sorry for the mistake

3

Please explain in more detail as to what your problem is?
Please show your relevant blocks and arduino/board sketches to help others help you....