drivers/radio/nrf24l01: Properly handle timeout.

The timeout condition was not handled before. Upon timeout, this
caused the chip to stay active until another send command changed
it's state.

Sometimes when it was unable to transmit the data, it got stuck
in the tx fifo causing it to fill up over time, which set the
TX_FULL flag in the STATUS register.

Since there was no exceptions raised, the user code could not
differentiate a successful send or a timeout condition.

Signed-off-by: Marcell Pünkösd <[email protected]>

Author: marcsello

micropython/drivers/radio/nrf24l01/nrf24l01.py

@@ -220,6 +220,13 @@ def send(self, buf, timeout=500):
         result = None
         while result is None and utime.ticks_diff(utime.ticks_ms(), start) < timeout:
             result = self.send_done()  # 1 == success, 2 == fail
+
+        if result is None:
+            # timed out, cancel sending and power down the module
+            self.flush_tx()
+            self.reg_write(CONFIG, self.reg_read(CONFIG) & ~PWR_UP)
+            raise OSError("timed out")
+
         if result == 2:
             raise OSError("send failed")