tfmini 0.1.3

A driver for the TFmini LiDAR sold by Sparkfun

TFmini

Usage

Reading the sensor returns the range in meters.

from __future__ import division, print_function
import time
from tfmini import TFmini

# create the sensor and give it a port and (optional) operating mode
tf = TFmini('/dev/tty.usbserial-A506BOT5', mode=TFmini.STD_MODE)

try:
    print('='*25)
    while True:
        d = tf.read()
        if d:
            print('Distance: {:5}'.format(d))
        else:
            print('No valid response')
        time.sleep(0.1)

except KeyboardInterrupt:
    tf.close()
    print('bye!!')

• TFmini(port, mode=5, retry=25): the constructor takes several inputs

  • port: serial port the sensor is connected too

  • mode: either standard (default) or decimal mode

  • retry: how many times the driver should search the serial port for the packet header. This only applies in standard mode.

• read(): in any mode, returns the distance in meters

• TFmini.strength: in standard mode, each packet contains the returned IR strength level. In decimal mode, this doesn’t exist and is always set to -1.

Standard (Packet) Mode

In this mode, a data packet is sent from the sensor:

packet = [0x59, 0x59, distL, distH, strL, strH, reserved, integration time, checksum]

Where the first two bytes 0x59, 0x59 are the header and each packet has a checksum to ensure the packet is valid data.

Decimal (String) Mode

In this mode, the sensor can sometimes returns an incorrect value because the ASCII string was read wrong across the serial port. There is no error checking in this mode.

Distance:  2.96
Distance:  2.96
Distance:  96.0 <<< Error
Distance:  2.95
Distance:  2.95
Distance:  2.96

References

• Sparkfun product page

• Manufacturer produce page

MIT License

Copyright (c) 2018 Kevin Walchko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.