lora: Multiple small fixes (including syncword, sx126x minimum config)

micropython/lora/lora-sx126x/lora/sx126x.py

@@ -163,6 +163,9 @@ def __init__(
         # 0x02 is 40us, default value appears undocumented but this is the SX1276 default
         self._ramp_val = 0x02
 
+        # Configure the SX126x at least once after reset
+        self._configured = False
+
         if reset:
             # If the caller supplies a reset pin argument, reset the radio
             reset.init(Pin.OUT, value=0)
@@ -383,24 +386,24 @@ def configure(self, lora_cfg):
                 # see
                 # https://www.thethingsnetwork.org/forum/t/should-private-lorawan-networks-use-a-different-sync-word/34496/15
                 syncword = 0x0404 + ((syncword & 0x0F) << 4) + ((syncword & 0xF0) << 8)
-            self._cmd(">BBH", _CMD_WRITE_REGISTER, _REG_LSYNCRH, syncword)
+            self._cmd(">BHH", _CMD_WRITE_REGISTER, _REG_LSYNCRH, syncword)
 
-        if "output_power" in lora_cfg:
+        if not self._configured or any(
+            key in lora_cfg for key in ("output_power", "pa_ramp_us", "tx_ant")
+        ):
             pa_config_args, self._output_power = self._get_pa_tx_params(
-                lora_cfg["output_power"], lora_cfg.get("tx_ant", None)
+                lora_cfg.get("output_power", self._output_power), lora_cfg.get("tx_ant", None)
             )
             self._cmd("BBBBB", _CMD_SET_PA_CONFIG, *pa_config_args)
 
-        if "pa_ramp_us" in lora_cfg:
-            self._ramp_val = self._get_pa_ramp_val(
-                lora_cfg, [10, 20, 40, 80, 200, 800, 1700, 3400]
-            )
+            if "pa_ramp_us" in lora_cfg:
+                self._ramp_val = self._get_pa_ramp_val(
+                    lora_cfg, [10, 20, 40, 80, 200, 800, 1700, 3400]
+                )
 
-        if "output_power" in lora_cfg or "pa_ramp_us" in lora_cfg:
-            # Only send the SetTxParams command if power level or PA ramp time have changed
             self._cmd("BBB", _CMD_SET_TX_PARAMS, self._output_power, self._ramp_val)
 
-        if any(key in lora_cfg for key in ("sf", "bw", "coding_rate")):
+        if not self._configured or any(key in lora_cfg for key in ("sf", "bw", "coding_rate")):
             if "sf" in lora_cfg:
                 self._sf = lora_cfg["sf"]
                 if self._sf < _CFG_SF_MIN or self._sf > _CFG_SF_MAX:
@@ -441,6 +444,7 @@ def configure(self, lora_cfg):
             self._reg_write(_REG_RX_GAIN, 0x96 if lora_cfg["rx_boost"] else 0x94)
 
         self._check_error()
+        self._configured = True
 
     def _invert_workaround(self, enable):
         # Apply workaround for DS 15.4 Optimizing the Inverted IQ Operation
@@ -465,7 +469,7 @@ def calibrate(self):
         # See DS 13.1.12 Calibrate Function
 
         # calibParam 0xFE means to calibrate all blocks.
-        self._cmd("<BB", _CMD_CALIBRATE, 0xFE)
+        self._cmd("BB", _CMD_CALIBRATE, 0xFE)
 
         time.sleep_us(_CALIBRATE_TYPICAL_TIME_US)
 
@@ -541,7 +545,7 @@ def start_recv(self, timeout_ms=None, continuous=False, rx_length=0xFF):
         else:
             timeout = 0  # Single receive mode, no timeout
 
-        self._cmd(">BBH", _CMD_SET_RX, timeout >> 16, timeout)
+        self._cmd(">BBH", _CMD_SET_RX, timeout >> 16, timeout)  # 24 bits
 
         return self._dio1
 
@@ -725,10 +729,10 @@ def _cmd(self, fmt, *write_args, n_read=0, write_buf=None, read_buf=None):
             return res
 
     def _reg_read(self, addr):
-        return self._cmd("BBBB", _CMD_READ_REGISTER, addr >> 8, addr & 0xFF, n_read=1)[0]
+        return self._cmd(">BHB", _CMD_READ_REGISTER, addr, 0, n_read=1)[0]
 
     def _reg_write(self, addr, val):
-        return self._cmd("BBBB", _CMD_WRITE_REGISTER, addr >> 8, addr & 0xFF, val & 0xFF)
+        return self._cmd(">BHB", _CMD_WRITE_REGISTER, addr, val & 0xFF)
 
 
 class _SX1262(_SX126x):

micropython/lora/lora-sx126x/manifest.py

@@ -1,3 +1,3 @@
-metadata(version="0.1.1")
+metadata(version="0.1.2")
 require("lora")
 package("lora")

micropython/lora/lora-sx127x/lora/sx127x.py

@@ -519,6 +519,9 @@ def configure(self, lora_cfg):
 
         self._reg_update(_REG_MODEM_CONFIG3, update_mask, modem_config3)
 
+        if "syncword" in lora_cfg:
+            self._reg_write(_REG_SYNC_WORD, lora_cfg["syncword"])
+
     def _reg_write(self, reg, value):
         self._cs(0)
         if isinstance(value, int):

micropython/lora/lora-sx127x/manifest.py

@@ -1,3 +1,3 @@
-metadata(version="0.1.0")
+metadata(version="0.1.1")
 require("lora")
 package("lora")

micropython/lora/lora-sync/lora/sync_modem.py

@@ -42,8 +42,8 @@ def send(self, packet, tx_at_ms=None):
 
         tx = True
         while tx is True:
-            tx = self.poll_send()
             self._sync_wait(will_irq)
+            tx = self.poll_send()
         return tx
 
     def recv(self, timeout_ms=None, rx_length=0xFF, rx_packet=None):

micropython/lora/lora-sync/manifest.py

@@ -1,3 +1,3 @@
-metadata(version="0.1.0")
+metadata(version="0.1.1")
 require("lora")
 package("lora")

micropython/lora/lora/lora/modem.py

@@ -37,10 +37,11 @@ def __init__(self, ant_sw):
         self._ant_sw = ant_sw
         self._irq_callback = None
 
-        # Common configuration settings that need to be tracked by all modem drivers
-        # (Note that subclasses may set these to other values in their constructors, to match
-        # the power-on-reset configuration of a particular modem.)
+        # Common configuration settings that need to be tracked by all modem drivers.
         #
+        # Where modem hardware sets different values after reset, the driver should
+        # set them back to these defaults (if not provided by the user), so that
+        # behaviour remains consistent between different modems using the same driver.
         self._rf_freq_hz = 0  # Needs to be set via configure()
         self._sf = 7  # Spreading factor
         self._bw_hz = 125000  # Reset value