Class: Rplidar::Driver

Inherits:
Object
  • Object
show all
Includes:
CSV, Util
Defined in:
lib/rplidar/driver.rb

Overview

Ruby implementation of driver of the SLAMTEC RPLIDAR A2.

Constant Summary collapse

COMMAND_GET_HEALTH =

Commands

0x52
COMMAND_GET_INFO = 
0x50
COMMAND_MOTOR_PWM = 
0xF0
COMMAND_SCAN = 
0x20
COMMAND_STOP = 
0x25
COMMAND_RESET = 
0x40
COMMANDS_WITH_RESPONSE = 
[
  COMMAND_GET_HEALTH,
  COMMAND_GET_INFO,
  COMMAND_SCAN
].freeze
RESPONSE_DESCRIPTOR_LENGTH =

Default length of responses

7
GET_INFO_RESPONSE_LENGTH = 
20
SCAN_DATA_RESPONSE_LENGTH = 
5
UART_BAUD_RATE = 
115_200

Instance Method Summary collapse

Methods included from Util

#binary_to_ints, #checksum, #ints_to_binary

Methods included from CSV

#dump_scans

Constructor Details

#initialize(port_address) ⇒ Driver

Returns a new instance of Driver.


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# File 'lib/rplidar/driver.rb', line 32

def initialize(port_address)
  @port_address = port_address
end

Instance Method Details

#clear_port ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 127

def clear_port
  while port.getbyte
  end
end

#close ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 132

def close
  @port.close if @port
end

#collect_scan_data_responses(iterations) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 64

def collect_scan_data_responses(iterations)
  responses = []
  iteration = -1
  while iteration < iterations
    response = scan_data_response
    iteration += 1 if response[:start]
    responses << response if iteration.between?(0, iterations - 1)
  end
  responses
end

#command(command) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 84

def command(command)
  request(command)
  response_descriptor if COMMANDS_WITH_RESPONSE.include?(command)
end

#current_state ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 36

def current_state
  descriptor = command(COMMAND_GET_HEALTH)
  raw_response = read_response(descriptor[:data_response_length])
  Rplidar::CurrentStateDataResponse.new(raw_response).response
end

#device_info ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 42

def device_info
  descriptor = command(COMMAND_GET_INFO)
  raw_response = read_response(descriptor[:data_response_length])
  Rplidar::DeviceInfoDataResponse.new(raw_response).response
end

#port ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 136

def port
  @port ||= Serial.new(@port_address, UART_BAUD_RATE, 8, :none, 1)
end

#read_response(length) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 116

def read_response(length)
  t = Time.now
  response = []
  while response.size < length
    byte = port.getbyte
    response << byte if byte
    raise 'Timeout while reading a byte from the port' if Time.now - t > 2
  end
  response
end

#request(command) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 89

def request(command)
  params = [0xA5, command]
  port.write(ints_to_binary(params))
  sleep 0.5
end

#request_with_payload(command, payload) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 95

def request_with_payload(command, payload)
  payload_string = ints_to_binary(payload, 'S<*')
  payload_size = payload_string.size

  string = ints_to_binary([0xA5, command, payload_size])
  string += payload_string
  string += ints_to_binary(checksum(string))

  port.write(string)
end

#reset ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 80

def reset
  command(COMMAND_RESET)
end

#response_descriptor ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 106

def response_descriptor
  raw_response = read_response(RESPONSE_DESCRIPTOR_LENGTH)
  Rplidar::ResponseDescriptor.new(raw_response).response
end

#scan(iterations = 1) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 56

def scan(iterations = 1)
  command(COMMAND_SCAN)
  responses = collect_scan_data_responses(iterations)
  stop

  responses
end

#scan_data_response ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 111

def scan_data_response
  raw_response = read_response(SCAN_DATA_RESPONSE_LENGTH)
  Rplidar::ScanDataResponse.new(raw_response).response
end

#start_motor(pwm = 660) ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 48

def start_motor(pwm = 660)
  request_with_payload(COMMAND_MOTOR_PWM, pwm)
end

#stop ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 75

def stop
  command(COMMAND_STOP)
  clear_port
end

#stop_motor ⇒ Object 


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# File 'lib/rplidar/driver.rb', line 52

def stop_motor
  request_with_payload(COMMAND_MOTOR_PWM, 0)
end