French FX-7 robot

Projects
Participants	Mi1es
Skills	Electronics, Soldering, Programming, Creative thinking
Status	Active
Niche	Electronics
Purpose	World domination

"Contrôle système! Contrôle système!"

Direct Drive control via RaspPI

Machine has been taken apart.. blblblalbla

H-bridge board has all the transistors of the original board on it for 4 full H-bridges that can drive all of the four bi-directional motors.

Original 'direct drive' Layout was as follows , with the connectors of the motors facing you:

• First block, gpio18, w1, gpio4, w7, Left tread
• Second block, gpio17,w0, gpio23,w4, Right treads
• Third block: gpio27,w2, gpio22,w3, hip
• Fourth block: gpio24, w5, gpio25,w6, arms

'Direct Drive' Python code

import RPi.GPIO as gpio
import time
import pygame
from pygame.locals import *


gpio.setmode(gpio.BOARD)
gpio.setup(7, gpio.OUT)
gpio.setup(11, gpio.OUT)
gpio.setup(13, gpio.OUT)
gpio.setup(15, gpio.OUT)

gpio.output(7, True)
gpio.output(11, True)

 while True:
    gpio.output(13, True)
    gpio.output(15, False)
    time.sleep(2)
    gpio.output(13, False)
    gpio.output(15, True)
    time.sleep(2)

pygame.init()
screen = pygame.display.set_mode((640,480))
pygame.display.set_caption("Pygame")
pygame.mouse.set_visible(0)

done = False
enable = 0
direction = 0
while not done:
    for event in pygame.event.get():
        if(event.type==KEYDOWN):
            print event
            if(event.key==273):
                direction=1;
                enable=1;
            if(event.key==274):
                direction=-1;
                enable=1;     
        if(event.type==KEYUP):
            print event
            if(event.key==273):
                direction=0;
                enable=0;
            if(event.key==274):
                direction=0;
                enable=0;

        if(enable==1):
            if(direction==1):
                print "Forwards"
                gpio.output(13, False)
                gpio.output(15, True)
            if(direction==-1):
                print "Backwards"
                gpio.output(13, True)
                gpio.output(15, False)
        else:
            gpio.output(13, False)
            gpio.output(15, False)

With this code-shim you can test the function of your code even without having RPi.GPIO loaded (like on most PC's) Note it doesnt implement all things yet; but enough to work for this project currently. Working on a shift-register help-library

class FAKEGPIO:
  def __init__(self):
    self.BOARD=1
    self.OUT=0
    self.IN=1
  def setmode(self,variant):
    print "Call: setmode: variant -> " + str(variant)
  def setup(self,pin, type):
    print "Call: setup : pin -> " + str(pin) + ", type -> " + str(type)
  def output(self,pin,state):
    print "Out:" + str(pin) + "-> " + str(state)

gpio = FAKEGPIO()

Shift-Register driving of robot

Since the RaspPI doesnt have much IO and the robot requires 8 output-pins just for the basic motor-control already, we've started looking at driving the outputs using shift-registers instead.

The proto-board has been re-wired to have two shift-registers hosted on it, connected in series, for a total of 16 outputs.

The motor-pins are connected to the first of the two shift-registers; this means that the last 8 bits of data shifted into the 16 bit register-space controls the motors as the first bit shifted in ends up being at the last-most position after 16 clock-cycles.

Shift-register layout

Shift-register layout
Register	Bit	Motor	Direction
1	0	Left Tread	Forwards
	1	Left Tread	Backwards
	2	Right Tread	Forwards
	3	Right Tread	Backwards
	4	Hip	Forwards
	5	Hip	Backwards
	6	Arms	Open
	7	Arms	Close
2	0	TBD	TBD
	1	TBD	TBD
	2	TBD	TBD
	3	TBD	TBD
	4	TBD	TBD
	5	TBD	TBD
	6	TBD	TBD
	7	TBD	TBD