Big STM32 boards topic

[bluejedi]

@Ludwig

@Ludwig

When using this workaround with MCCI LMIC I ran into certain issues that I have not yet further investigated.

If using the newer MCCI version, be aware that the maximum clock error is limited to 0.4% if the LMIC_ENABLE_arbitrary_clock_error is not defined. See also https://github.com/mcci-catena/arduino-lmic/blob/master/README.md#lmic_setclockerror .
With the STM32L071 running from the 16MHz HSI a clock error setting of 0.4% works for me. Though I have not tested at highest or lowest expected temperatures yet, which will have an effect on clock drift.

With a bluepill board (STM32F103C8T6, 128k) I am unable to get MCCI LMIC library working.

IDE: PlatformIO, board = bluepill_f103c8_128k

LMIC libraries:

• MCCI LoRaWAN LMIC library, version 3.1.0
• LMIC Arduino, version 1.5.0+arduino-3

Sketch: ttn-otaa.ino included with above MCCI LMIC library.

Modifications to sketch:

• Added unhandled events (see issue #550).
  (No notification is printed for EV_RXSTART in order not to mess up timing.)
• Added conditional compilation to exclude MCCI LMIC specific events/features when using the LMIC-Arduino library.

(Switching between both LMIC libraries can be done simply by specifying the corresponding library dependency in the platformio.ini project configuration file.)

When using the LMIC-Arduino library the example works fine (uplinks and downlinks) and does not even require ClockError to be set.

When using the MCCI LoRaWAN LMIC library evrything appears to hang after the first EV_TXSTART event (while it attempts to join).
After the initial join request no subsequent join (retry) requests are made (not visible on TTN Console). Normally, when the first join request fails (e.g. because of timing related downlink issues) a subsequent join request will be made within minutes. This is however not the case and the node appears to be hanging (waiting indefinitely, or crashed).