Fails on Feather M4 unless self._write_u8(_RH_RF95_REG_01_OP_MODE, 0b10001000) is called in __init__()

[brennen]

At line 357 in adafruit_rfm9x.py, I was getting the exception with Failed to configure radio for LoRa mode, check wiring!. Changed:

--- lib/adafruit_rfm9x.py       2018-08-04 16:14:14.000000000 -0600
+++ src/lib/adafruit_rfm9x.py   2018-08-06 00:38:26.275907581 -0600
@@ -354,10 +354,10 @@
             # Also set long range mode (LoRa mode) as it can only be done in sleep.
             self.sleep()
             self.long_range_mode = True
-            #self._write_u8(_RH_RF95_REG_01_OP_MODE, 0b10001000)
+            self._write_u8(_RH_RF95_REG_01_OP_MODE, 0b10001000)
             time.sleep(0.01)
-            #val = self._read_u8(_RH_RF95_REG_01_OP_MODE)
-            #print('op mode: {0}'.format(bin(val)))
+            val = self._read_u8(_RH_RF95_REG_01_OP_MODE)
+            print('op mode: {0}'.format(bin(val)))
             if self.operation_mode != SLEEP_MODE or not self.long_range_mode:
                 raise RuntimeError('Failed to configure radio for LoRa mode, check wiring!')
         except OSError:

...now seems to work.

[jerryneedell]

FYI - I have reproduced this error on a Fearther_M4_Express and also confirmed that uncommenting the first line

self._write_u8(_RH_RF95_REG_01_OP_MODE, 0b10001000)

fixes it.

I'll do some digging to see what is going on.

[jerryneedell]

aha -- there is some sense in the world.. The issue is not the comment lines, but teh speed of the M4.
leaving the lines commented but adding a time.sleep(.01) immediately after the self.sleep() call also fixes the problem. without the delay, it looks like the self.long_range_mode = True is getting missed on the M4.