This sketch transmits sample messages at a constant rate using the Helium Alpha modem, bridge and back-end. When a data stream is sent, the Helium Alpha system eventually hangs. When hung, the Arduino is functioning normally. The modem is blinking normally. The bridge is blinking normally. However, no data is received by the Helium-RED application.

The server.py is a elementary TCP server that prints whatever is sent on to TCP socket. Run the server and then configure a TCP endpoint in Helium-RED.

To check for lost packets, copy the output of the server to a text editor to count the number of messages received (lines). Subtract the last sequence number from the first to see how many messages were sent.

The sketch sends a message with a sequence number, the Arduino uptime (millis), the time at which the message was scheduled to be sent, and a newline (for convenience). The global period variable in the sketch determines the period between messages.

With 10ms message period, the Alpha system hangs within a minute or two. I set Helium-RED to forward messages to a TCP socket. Only 30% of messages are received on the TCP socket. Many messages are out of order. Similar performance message loss can be observed using a MQTT endpoint instead of a TCP endpoint.

With 100ms message period, the system can run for tens of minutes, but will eventually crash. 99% of messages are received. The messages are generally received in the correct order.

When the system is hung, the Arduino is still sending messages. The bridge LEDs are flashing as if it were receiving the messages. If the Arduino is restarted, it cannot reconnect to the bridge. The system can be restored to operation by power-cycling both the bridge and modem.