Fixed example for RPLidar firmware 1.29

README.rst

@@ -33,33 +33,24 @@ Usage Example
 .. code-block:: python
 
     import os
-    from math import cos, sin, pi, floor
-    import pygame
-    from adafruit_circuitpython_rplidar import RPLidar
-
-    # Set up pygame and the display
-    os.putenv('SDL_FBDEV', '/dev/fb1')
-    pygame.init()
-    lcd = pygame.display.set_mode((320,240))
-    pygame.mouse.set_visible(False)
-    lcd.fill((0,0,0))
-    pygame.display.update()
+    from math import floor
+    from adafruit_rplidar import RPLidar
+
 
     # Setup the RPLidar
     PORT_NAME = '/dev/ttyUSB0'
-    lidar = RPLidar(None, PORT_NAME)
+    lidar = RPLidar(None, PORT_NAME, timeout=3)
 
     # used to scale data to fit on the screen
     max_distance = 0
 
     def process_data(data):
-        # Do something useful with the data
-        pass
+        print(data)
 
     scan_data = [0]*360
 
     try:
-        print(lidar.get_info())
+    #    print(lidar.get_info())
         for scan in lidar.iter_scans():
             for (_, angle, distance) in scan:
                 scan_data[min([359, floor(angle)])] = distance

adafruit_rplidar.py

@@ -11,6 +11,7 @@
 
 * Author(s): Dave Astels
 * Based on https://github.com/SkoltechRobotics/rplidar by Artyom Pavlov
+* and updates from https://github.com/Roboticia/RPLidar by Julien JEHL
 
 Implementation Notes
 --------------------
@@ -23,16 +24,17 @@
 * Adafruit CircuitPython firmware for the supported boards:
   https://github.com/adafruit/circuitpython/releases
 
-Version 0.0.1 does NOT support CircuitPython. Future versions will.
+The Current Version does NOT support CircuitPython. Future versions will.
 """
 
 import struct
 import sys
 import time
 import warnings
+from collections import namedtuple
 
 # pylint:disable=invalid-name,undefined-variable,global-variable-not-assigned
-# pylint:disable=too-many-arguments,raise-missing-from
+# pylint:disable=too-many-arguments,raise-missing-from,too-many-instance-attributes
 
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_RPLIDAR.git"
@@ -46,16 +48,12 @@
 STOP_BYTE = b"\x25"
 RESET_BYTE = b"\x40"
 
-SCAN_BYTE = b"\x20"
-FORCE_SCAN_BYTE = b"\x21"
-
 DESCRIPTOR_LEN = 7
 INFO_LEN = 20
 HEALTH_LEN = 3
 
 INFO_TYPE = 4
 HEALTH_TYPE = 6
-SCAN_TYPE = 129
 
 # Constants & Command to start A2 motor
 MAX_MOTOR_PWM = 1023
@@ -68,6 +66,18 @@
     2: "Error",
 }
 
+SCAN_TYPE_NORMAL = 0
+SCAN_TYPE_FORCE = 1
+SCAN_TYPE_EXPRESS = 2
+
+_SCAN_TYPES = (
+    {"byte": b"\x20", "response": 129, "size": 5},
+    {"byte": b"\x21", "response": 129, "size": 5},
+    {"byte": b"\x82", "response": 130, "size": 84},
+)
+
+express_packet = namedtuple("express_packet", "distance angle new_scan start_angle")
+
 
 class RPLidarException(Exception):
     """Basic exception class for RPLidar"""
@@ -88,6 +98,17 @@ def _process_scan(raw):
     return new_scan, quality, angle, distance
 
 
+def _process_express_scan(data, new_angle, frame):
+    new_scan = (new_angle < data.start_angle) & (frame == 1)
+    angle = (
+        data.start_angle
+        + ((new_angle - data.start_angle) % 360) / 32 * frame
+        - data.angle[frame - 1]
+    ) % 360
+    distance = data.distance[frame - 1]
+    return new_scan, None, angle, distance
+
+
 class RPLidar:
     """Class for communicating with RPLidar rangefinder scanners"""
 
@@ -97,6 +118,12 @@ class RPLidar:
     timeout = 1  #: Serial port timeout
     motor = False  #: Is motor running?
     baudrate = 115200  #: Baudrate for serial port
+    scanning = False
+    descriptor_size = 0
+    scan_type = SCAN_TYPE_NORMAL
+    express_frame = 32
+    express_data = False
+    express_old_data = None
 
     def __init__(self, motor_pin, port, baudrate=115200, timeout=1, logging=False):
         """Initialize RPLidar object for communicating with the sensor.
@@ -152,7 +179,6 @@ def connect(self):
                     parity=serial.PARITY_NONE,
                     stopbits=serial.STOPBITS_ONE,
                     timeout=self.timeout,
-                    dsrdtr=True,
                 )
             except serial.SerialException as err:
                 raise RPLidarException(
@@ -253,7 +279,7 @@ def info(self):
         if dtype != INFO_TYPE:
             raise RPLidarException("Wrong response data type")
         raw = self._read_response(dsize)
-        serialnumber_bytes = struct.unpack("BBBBBBBBBBBBBBBB", raw[4:])
+        serialnumber_bytes = struct.unpack("B" * len(raw[4:]), raw[4:])
         serialnumber = "".join(reversed(["%02x" % b for b in serialnumber_bytes]))
         data = {
             "model": raw[0],
@@ -294,13 +320,67 @@ def health(self):
 
     def clear_input(self):
         """Clears input buffer by reading all available data"""
+        if self.scanning:
+            raise RPLidarException("Clearing not allowed during active scanning!")
+        self._serial_port.flushInput()
+        self.express_frame = 32
+        self.express_data = False
+
+    def start(self, scan_type=SCAN_TYPE_NORMAL):
+        """Start the scanning process
+        Parameters
+        ----------
+        scan : normal, force or express.
+        """
+        if self.scanning:
+            raise RPLidarException("Scanning already running!")
+        # Start the scanning process, enable laser diode and the
+        # measurement system
+        status, error_code = self.health
+        self.log("debug", "Health status: %s [%d]" % (status, error_code))
+        if status == _HEALTH_STATUSES[2]:
+            self.log(
+                "warning",
+                "Trying to reset sensor due to the error. "
+                "Error code: %d" % (error_code),
+            )
+            self.reset()
+            status, error_code = self.health
+            if status == _HEALTH_STATUSES[2]:
+                raise RPLidarException(
+                    "RPLidar hardware failure. " "Error code: %d" % error_code
+                )
+        elif status == _HEALTH_STATUSES[1]:
+            self.log(
+                "warning",
+                "Warning sensor status detected! " "Error code: %d" % (error_code),
+            )
+        cmd = _SCAN_TYPES[scan_type]["byte"]
+        self.log("info", "starting scan process in %s mode" % scan_type)
+
+        if scan_type == "express":
+            self._send_payload_cmd(cmd, b"\x00\x00\x00\x00\x00")
+        else:
+            self._send_cmd(cmd)
+
+        dsize, is_single, dtype = self._read_descriptor()
+        if dsize != _SCAN_TYPES[scan_type]["size"]:
+            raise RPLidarException("Wrong info reply length")
+        if is_single:
+            raise RPLidarException("Not a multiple response mode")
+        if dtype != _SCAN_TYPES[scan_type]["response"]:
+            raise RPLidarException("Wrong response data type")
+        self.descriptor_size = dsize
+        self.scan_type = scan_type
+        self.scanning = True
 
     def stop(self):
         """Stops scanning process, disables laser diode and the measurement
         system, moves sensor to the idle state."""
         self.log("info", "Stopping scanning")
         self._send_cmd(STOP_BYTE)
         time.sleep(0.001)
+        self.scanning = False
         self.clear_input()
 
     def reset(self):
@@ -309,8 +389,9 @@ def reset(self):
         self.log("info", "Resetting the sensor")
         self._send_cmd(RESET_BYTE)
         time.sleep(0.002)
+        self.clear_input()
 
-    def iter_measurements(self, max_buf_meas=500):
+    def iter_measurements(self, max_buf_meas=500, scan_type=SCAN_TYPE_NORMAL):
         """Iterate over measurements. Note that consumer must be fast enough,
         otherwise data will be accumulated inside buffer and consumer will get
         data with increasing lag.
@@ -334,37 +415,11 @@ def iter_measurements(self, max_buf_meas=500):
             In millimeter unit. Set to 0 when measurement is invalid.
         """
         self.start_motor()
-        status, error_code = self.health
-        self.log("debug", "Health status: %s [%d]" % (status, error_code))
-        if status == _HEALTH_STATUSES[2]:
-            self.log(
-                "warning",
-                "Trying to reset sensor due to the error. "
-                "Error code: %d" % (error_code),
-            )
-            self.reset()
-            status, error_code = self.health
-            if status == _HEALTH_STATUSES[2]:
-                raise RPLidarException(
-                    "RPLidar hardware failure. " "Error code: %d" % error_code
-                )
-        elif status == _HEALTH_STATUSES[1]:
-            self.log(
-                "warning",
-                "Warning sensor status detected! " "Error code: %d" % (error_code),
-            )
-        cmd = SCAN_BYTE
-        self._send_cmd(cmd)
-        dsize, is_single, dtype = self._read_descriptor()
-        if dsize != 5:
-            raise RPLidarException("Wrong info reply length")
-        if is_single:
-            raise RPLidarException("Not a multiple response mode")
-        if dtype != SCAN_TYPE:
-            raise RPLidarException("Wrong response data type")
+        if not self.scanning:
+            self.start(scan_type)
+
         while True:
-            raw = self._read_response(dsize)
-            self.log_bytes("debug", "Received scan response: ", raw)
+            dsize = self.descriptor_size
             if max_buf_meas:
                 data_in_buf = self._serial_port.in_waiting
                 if data_in_buf > max_buf_meas * dsize:
@@ -374,7 +429,50 @@ def iter_measurements(self, max_buf_meas=500):
                         "Clearing buffer..." % (data_in_buf // dsize, max_buf_meas),
                     )
                     self._serial_port.read(data_in_buf // dsize * dsize)
-            yield _process_scan(raw)
+            if self.scan_type == SCAN_TYPE_NORMAL:
+                raw = self._read_response(dsize)
+                self.log_bytes("debug", "Received scan response: ", raw)
+                yield _process_scan(raw)
+            elif self.scan_type == SCAN_TYPE_EXPRESS:
+                if self.express_frame == 32:
+                    self.express_frame = 0
+                    if not self.express_data:
+                        self.log("debug", "reading first time bytes")
+                        self.express_data = ExpressPacket.from_string(
+                            self._read_response(dsize)
+                        )
+
+                    self.express_old_data = self.express_data
+                    self.log(
+                        "debug",
+                        "set old_data with start_angle %f"
+                        % self.express_old_data.start_angle,
+                    )
+                    self.express_data = ExpressPacket.from_string(
+                        self._read_response(dsize)
+                    )
+                    self.log(
+                        "debug",
+                        "set new_data with start_angle %f"
+                        % self.express_data.start_angle,
+                    )
+
+                self.express_frame += 1
+                self.log(
+                    "debug",
+                    "process scan of frame %d with angle : "
+                    "%f and angle new : %f"
+                    % (
+                        self.express_frame,
+                        self.express_old_data.start_angle,
+                        self.express_data.start_angle,
+                    ),
+                )
+                yield _process_express_scan(
+                    self.express_old_data,
+                    self.express_data.start_angle,
+                    self.express_frame,
+                )
 
     def iter_measurments(self, max_buf_meas=500):
         """For compatibility, this method wraps `iter_measurements`"""
@@ -414,3 +512,44 @@ def iter_scans(self, max_buf_meas=500, min_len=5):
                 scan = []
             if quality > 0 and distance > 0:
                 scan.append((quality, angle, distance))
+
+
+class ExpressPacket(express_packet):
+    """Class representing a Express type Packet"""
+
+    sync1 = 0xA
+    sync2 = 0x5
+    sign = {0: 1, 1: -1}
+
+    @classmethod
+    def from_string(cls, data):
+        """Decode and Instantiate the class from a string packet"""
+        packet = bytearray(data)
+
+        if (packet[0] >> 4) != cls.sync1 or (packet[1] >> 4) != cls.sync2:
+            raise ValueError("try to parse corrupted data ({})".format(packet))
+
+        checksum = 0
+        for b in packet[2:]:
+            checksum ^= b
+        if checksum != (packet[0] & 0b00001111) + ((packet[1] & 0b00001111) << 4):
+            raise ValueError("Invalid checksum ({})".format(packet))
+
+        new_scan = packet[3] >> 7
+        start_angle = (packet[2] + ((packet[3] & 0b01111111) << 8)) / 64
+
+        d = a = ()
+        for i in range(0, 80, 5):
+            d += ((packet[i + 4] >> 2) + (packet[i + 5] << 6),)
+            a += (
+                ((packet[i + 8] & 0b00001111) + ((packet[i + 4] & 0b00000001) << 4))
+                / 8
+                * cls.sign[(packet[i + 4] & 0b00000010) >> 1],
+            )
+            d += ((packet[i + 6] >> 2) + (packet[i + 7] << 6),)
+            a += (
+                ((packet[i + 8] >> 4) + ((packet[i + 6] & 0b00000001) << 4))
+                / 8
+                * cls.sign[(packet[i + 6] & 0b00000010) >> 1],
+            )
+        return cls(d, a, new_scan, start_angle)