Merge pull request #12 from jerryneedell/jerryn_header

 Add access to RadioHead header

adafruit_rfm9x.py

@@ -33,7 +33,7 @@
 import digitalio
 from micropython import const
 
-import adafruit_bus_device.spi_device as spi_device
+import adafruit_bus_device.spi_device as spidev
 
 
 __version__ = "0.0.0-auto.0"
@@ -338,8 +338,8 @@ def __init__(self, spi, cs, reset, frequency, *, preamble_length=8,
         self.high_power = high_power
         # Device support SPI mode 0 (polarity & phase = 0) up to a max of 10mhz.
         # Set Default Baudrate to 5MHz to avoid problems
-        self._device = spi_device.SPIDevice(spi, cs, baudrate=baudrate,
-                                            polarity=0, phase=0)
+        self._device = spidev.SPIDevice(spi, cs, baudrate=baudrate,
+                                        polarity=0, phase=0)
         # Setup reset as a digital input (default state for reset line according
         # to the datasheet).  This line is pulled low as an output quickly to
         # trigger a reset.  Note that reset MUST be done like this and set as
@@ -533,27 +533,32 @@ def rssi(self):
         # Remember in LoRa mode the payload register changes function to RSSI!
         return self._read_u8(_RH_RF95_REG_1A_PKT_RSSI_VALUE) - 137
 
-    def send(self, data, timeout=2.):
-        """Send a string of data using the transmitter.  You can only send 252
-        bytes at a time (limited by chip's FIFO size and appended headers). Note
-        this appends a 4 byte header to be compatible with the RadioHead library.
-        The timeout is just to prevent a hang (arbitrarily set to 2 Seconds).
+    def send(self, data, timeout=2.,
+             tx_header=(_RH_BROADCAST_ADDRESS, _RH_BROADCAST_ADDRESS, 0, 0)):
+        """Send a string of data using the transmitter.
+           You can only send 252 bytes at a time
+           (limited by chip's FIFO size and appended headers).
+           This appends a 4 byte header to be compatible with the RadioHead library.
+           The tx_header defaults to using the Broadcast addresses. It may be overidden
+           by specifying a 4-tuple of bytes containing (To,From,ID,Flags)
+           The timeout is just to prevent a hang (arbitrarily set to 2 seconds)
         """
         # Disable pylint warning to not use length as a check for zero.
         # This is a puzzling warning as the below code is clearly the most
         # efficient and proper way to ensure a precondition that the provided
         # buffer be within an expected range of bounds.  Disable this check.
         # pylint: disable=len-as-condition
         assert 0 < len(data) <= 252
+        assert len(tx_header) == 4, "tx header must be 4-tuple (To,From,ID,Flags)"
         # pylint: enable=len-as-condition
         self.idle()  # Stop receiving to clear FIFO and keep it clear.
         # Fill the FIFO with a packet to send.
         self._write_u8(_RH_RF95_REG_0D_FIFO_ADDR_PTR, 0x00)  # FIFO starts at 0.
         # Write header bytes.
-        self._write_u8(_RH_RF95_REG_00_FIFO, _RH_BROADCAST_ADDRESS) # txHeaderTo
-        self._write_u8(_RH_RF95_REG_00_FIFO, _RH_BROADCAST_ADDRESS) # txHeaderFrom
-        self._write_u8(_RH_RF95_REG_00_FIFO, 0x00) # txHeaderId
-        self._write_u8(_RH_RF95_REG_00_FIFO, 0x00) # txHeaderFlags
+        self._write_u8(_RH_RF95_REG_00_FIFO, tx_header[0]) # Header: To
+        self._write_u8(_RH_RF95_REG_00_FIFO, tx_header[1]) # Header: From
+        self._write_u8(_RH_RF95_REG_00_FIFO, tx_header[2]) # Header: Id
+        self._write_u8(_RH_RF95_REG_00_FIFO, tx_header[3]) # Header: Flags
         # Write payload.
         self._write_from(_RH_RF95_REG_00_FIFO, data)
         # Write payload and header length.
@@ -574,16 +579,29 @@ def send(self, data, timeout=2.):
         if timed_out:
             raise RuntimeError('Timeout during packet send')
 
-    def receive(self, timeout=0.5, keep_listening=True):
-        """Wait to receive a packet from the receiver. Will wait for up to
-        timeout amount of seconds for a packet to be received and decoded. If
-        a packet is found the payload bytes are returned, otherwise None is
-        returned (which indicates the timeout elapsed with no reception). Note
-        this assumes a 4-byte header is prepended to the data for compatibilty
-        with the RadioHead library (the header is not validated nor returned).
-        If keep_listening is True (the default) the chip will immediately enter
-        listening mode after reception of a packet, otherwise it will fall back
-        to idle mode and ignore any future reception.
+
+
+    def receive(self, timeout=0.5, keep_listening=True, with_header=False,
+                rx_filter=_RH_BROADCAST_ADDRESS):
+        """Wait to receive a packet from the receiver. Will wait for up to timeout_s amount of
+           seconds for a packet to be received and decoded. If a packet is found the payload bytes
+           are returned, otherwise None is returned (which indicates the timeout elapsed with no
+           reception).
+           If keep_listening is True (the default) the chip will immediately enter listening mode
+           after reception of a packet, otherwise it will fall back to idle mode and ignore any
+           future reception.
+           A 4-byte header must be prepended to the data for compatibilty with the
+           RadioHead library.
+           The header consists of a 4 bytes (To,From,ID,Flags). The default setting will accept
+           any  incomming packet and strip the header before returning the packet to the caller.
+           If with_header is True then the 4 byte header will be returned with the packet.
+           The payload then begins at packet[4].
+           rx_fliter may be set to reject any "non-broadcast" packets that do not contain the
+           specfied "To" value in the header.
+           if rx_filter is set to 0xff (_RH_BROADCAST_ADDRESS) or if the  "To" field (packet[[0])
+           is equal to 0xff then the packet will be accepted and returned to the caller.
+           If rx_filter is not 0xff and packet[0] does not match rx_filter then
+           the packet is ignored and None is returned.
         """
         # Make sure we are listening for packets.
         self.listen()
@@ -612,7 +630,10 @@ def receive(self, timeout=0.5, keep_listening=True):
                 packet = bytearray(length)
                 # Read the packet.
                 self._read_into(_RH_RF95_REG_00_FIFO, packet)
-                # strip off the header
+            if (rx_filter != _RH_BROADCAST_ADDRESS and packet[0] != _RH_BROADCAST_ADDRESS
+                    and packet[0] != rx_filter):
+                packet = None
+            if not with_header:  # skip the header if not wanted
                 packet = packet[4:]
             # Listen again if necessary and return the result packet.
         if keep_listening: