Adding a costum dynamixel module to pypot

This howto show you how to use Rhoban Cell Load card with pypot.

First, you have to add your model into known models:

import pypot
from pypot.dynamixel import conversion as conv
conv.dynamixelModels[5004]='RhobanLoadBoard'

Then, we use _DxlControl :

import pypot
import pypot.dynamixel

from pypot.dynamixel.io.abstract_io import  _DxlControl,_DxlAccess

ports = pypot.dynamixel.get_available_ports()
dxl_io = pypot.dynamixel.DxlIO(ports[0])

# now we can create our own accessor

def dxl_to_loadvalue(value,model):
    return ((value[0]) | (value[1] << 8) | (value[2] << 16)) & 0xffffffff


control=_DxlControl(name,
                        address=0x24, length=1,nb_elem=3,
                        access=_DxlAccess.readonly,
                        models=['RhobanLoadBoard'],
                        dxl_to_si=dxl_to_loadvalue,
                        si_to_dxl=None,
                        getter_name="get_loadcell1",
                        setter_name=None)
dxl_io._generate_accessors(control)

For the rhoban board, each cell value is 3 bytes to read at adress 0x24, 0x27, 0x30 and 0x33. We can create an accessor for each cell using the following loop:

def dxl_to_loadvalue(value,model):
    return ((value[0]) | (value[1] << 8) | (value[2] << 16)) & 0xffffffff

for i in [1,2,3,4]:
    name="loadcell%d"%i
    getter="get_loadcell%d"%i
    control=_DxlControl(name,
                        address=0x24+3*(i-1), length=1,nb_elem=3,
                        access=_DxlAccess.readonly,
                        models=['RhobanLoadBoard'],
                        dxl_to_si=dxl_to_loadvalue,
                        si_to_dxl=None,
                        getter_name=getter,
                        setter_name=None)
    dxl_io._generate_accessors(control)

Now, we can read the value of each cell

dxl_io.get_loadcell1((123,))
dxl_io.get_loadcell2((123,))
dxl_io.get_loadcell3((123,))
dxl_io.get_loadcell4((123,))

The id of the board (here is 123) is retrieved using

dxl_io.scan()