Informatique, électronique et train miniature (3/4)
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Mise en pratique
Vue d'ensemble
Dans un souci de réalisme, un joystick est utilisé.
Il est censé simuler
- l'accélération progressive par application d'une certaine puissance
- le freinage plus ou moins intense suivant les circonstances
- la sélection de la marche avant ou de la marche arrière
Composants et schéma de raccordement
- Microcontrôleur Raspberry Pico RP2040
- Régulateur de tension 12V - 5V
- Contrôleur DC L298H
- Joystick
- Afficheur OLED
Réalisation pratique
Quelques précautions :
- veillez à bien enlever les « jumpers » sur le contrôleur DC (4 + 1 = 5 au total : cf schéma ci-dessus) ;
- l'afficheur Olimex utilisé doit être alimenté en 3.3 V, de même que le joystick.
Code Micropython (main.py)
# Copyright (C) 2018-2023 PhS & Quintilien
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the GNU General Public License for more details.
#
#
# Rev. 2.12 - 23 sept. 2023
#
from machine import Pin, ADC, Timer, I2C, UART, PWM
import time
import ssd1306
# pwm
pwm_ena = PWM(machine.Pin(18))
pwm_ena.freq(500)
pwm_in1 = machine.Pin(17, Pin.OUT)
pwm_in2 = machine.Pin(16, Pin.OUT)
# joystick (on 3,3 V !)
adc0 = ADC(Pin(26, mode=Pin.IN)) # joystick X
adc1 = ADC(Pin(27, mode=Pin.IN)) # joystick Y
adc2 = Pin(28, Pin.IN, Pin.PULL_UP) # joystick switch
# i2C
i2c = I2C(0, sda=machine.Pin(8), scl=machine.Pin(9), freq=400000)
print ('i2C found : ',i2c.scan())
lcd = ssd1306.SSD1306_I2C( 128, 64, i2c )
lcd.text("Ready", 0,0,1) # column, ligne * 10, 1
lcd.show() # Display!
# matrix for big display
big_num = [
[
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ]
] ,
[
[ 0,0,1,0,0 ] ,
[ 0,1,1,0,0 ] ,
[ 1,0,1,0,0 ] ,
[ 0,0,1,0,0 ] ,
[ 0,0,1,0,0 ] ,
[ 0,0,1,0,0 ] ,
[ 0,0,1,0,0 ] ,
[ 1,1,1,1,1 ]
] ,
[
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,0,0,1,0 ] ,
[ 0,0,1,0,0 ] ,
[ 0,1,0,0,0 ] ,
[ 1,0,0,0,0 ] ,
[ 1,1,1,1,1 ]
] ,
[
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 0,0,0,0,1 ] ,
[ 0,0,1,1,0 ] ,
[ 0,0,0,0,1 ] ,
[ 0,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ]
] ,
[
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,1 ] ,
[ 0,0,0,0,1 ] ,
[ 0,0,0,0,1 ] ,
[ 0,0,0,0,1 ]
] ,
[
[ 1,1,1,1,1 ] ,
[ 1,0,0,0,0 ] ,
[ 1,0,0,0,0 ] ,
[ 1,1,1,1,0 ] ,
[ 0,0,0,0,1 ] ,
[ 0,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ]
] ,
[
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,0 ] ,
[ 1,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ]
] ,
[
[ 1,1,1,1,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,0,0,0,1 ] ,
[ 0,0,0,1,0 ] ,
[ 0,0,1,0,0 ] ,
[ 0,1,0,0,0 ] ,
[ 0,1,0,0,0 ] ,
[ 0,1,0,0,0 ]
] ,
[
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ]
] ,
[
[ 0,1,1,1,0 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,1 ] ,
[ 0,0,0,0,1 ] ,
[ 1,0,0,0,1 ] ,
[ 0,1,1,1,0 ]
]
]
def display_big_numbers(v):
v2 = list()
for tmp in (str(v)):
v2.append(int(tmp))
v2.reverse()
# fill_rect( x, y, w, h, c )
lcd.fill_rect( 10,20,118,40, 0 )
for p, n in enumerate ( v2 ): # p = position, n = digit to display
for l in range (8):
for c in range(5):
if big_num[n][l][c] == 1:
lcd.fill_rect( c*5+(4-p)*30-20,l*5+20, 5, 5, 1 )
lcd.show()
tictac = 1
def running(x):
global tictac
if tictac == 1:
lcd.fill_rect( 0,59,4,4,1 ) # fill_rect( x, y, w, h, c )
else:
lcd.fill_rect( 0,59,4,4,0 ) # fill_rect( x, y, w, h, c )
tictac = tictac * (-1)
lcd.show()
def set_speed(number=0, speed=0, acceleration=10, deceleration=12, direction=0):
global vc, di, vt, ac, dc, dt
vt[number] = speed
if direction != 0:
dt[number] = direction
if vc[number] < speed:
ac[number] = acceleration
dc[number] = 0
if vc[number] > speed:
ac[number] = 0
dc[number] = deceleration
def set_pwm():
global vc, dac, ddc, vt, ac, dc, di, dt, m1, m2, vp, cja, cjd
global ch
global pwm_ena, pwm_in1, pwm_in2
if di[ch] == 0:
pwm_in1.value(0)
pwm_in2.value(0)
if di[ch] == 1:
pwm_in1.value(1)
pwm_in2.value(0)
if di[ch] == -1:
pwm_in1.value(0)
pwm_in2.value(1)
if vc[ch] == 0:
pwm_ena.duty_u16( 0 )
else:
pwm_ena.duty_u16( ( vc[ch] + 1 ) * 64 - 1 )
def display_ch():
global di, ch, lcd
lcd.fill_rect( 110,0,20,10,0 ) # fill_rect( x, y, w, h, c )
if di[ch] == 0:
lcd.text("--", 110,1,1) # column, line * 10, 1
if di[ch] == 1:
lcd.text("->", 110,1,1) # column, line * 10, 1
if di[ch] == -1:
lcd.text("<-", 110,1,1) # column, line * 10, 1
# speed control : settings for freq(PWM) = 500 Hz
# Code designed to manage 3 locomotives
ch = 0 # Loco 0 selected
vp = [0, 0, 0] # previous speed
vt = [0, 0, 0] # target speed
ac = [0, 0, 0] # acceleration
dc = [0, 0, 0] # deceleration
vc = [0, 0, 0] # current speed
di = [1, 1, 1] # current direction
dt = [1, 1, 1] # target direction
m1 = [250, 250, 250] # minimum pulse threshold when accelerate
m2 = [250, 250, 250] # minimum pulse threshold when decelerate
dac = [10, 10, 10] # default acceleration
ddc = [18, 18, 18] # default deceleration
cja = [128, 256, 256] # coeff acceleration joystick
cjd = [64, 64, 64] # coeff deceleration joystick
def speed_control(x):
global lcd
global vc, dac, ddc, vt, ac, dc, di, dt, m1, m2, vp, cja, cjd
jy = int ( ( 32767 - adc1.read_u16() ) / 32 ) # y -1023 -> 0 -> 1023
if jy > 1000:
jy = 1023
if jy <= -1000:
jy = -1023
if jy > -100 and jy < 100:
jy = 0
#
jx = int ( ( 32767 - adc0.read_u16() ) / -32 ) # x -1023 -> 0 -> 1023
if jx > 1000:
jx = 1023
if jx <= -1000:
jx = -1023
if jx > -300 and jx < 300:
jx = 0
#
jsw = adc2.value()
#
if jx > 750:
dt[ch] = 1 # target direction
if jx < -750:
dt[ch] = -1 # target direction
jt = 0 # joystick target speed
ja = 0 # joystick acceleration
jd = 0 # joystick deceleration
if jy > 0:
jt = jy # target speed
ja = int ( jy / cja[ch] ) # acceleration ( TO BE "FINE TUNED" )
if jy < 0:
jd = int ( jy / cjd[ch] * -1 ) # deceleration
# designed to manage more than one locomotive simultaneously !
for i, v in enumerate (vc):
if di[i] != dt[i]: # changing direction -> stop before !
vc[i] = 0
vt[i] = 0
ac[i] = 0
dc[i] = 0
di[i] = dt[i]
set_pwm()
if di[i] != 0:
if i == ch: # joystick activated
if v < jt and ja !=0 : # accelerate with joystick
if v + ja > jt:
vc[i] = jt
else:
if vc[i] + ja < m1[i]:
vc[i] = m1[i]
else:
vc[i] = v + ja
if v > vt[i] and jd !=0 : # decelerate with joystick
if v - jd < jt:
vc[i] = jt
else:
vc[i] = vc[i] - jd
if vc[i] < m2[i]: # if target < minimum pulse => target = min
vc[i] = 0
if v < vt[i] and ac[i] !=0 : # accelerate with external instruction
if v + ac[i] >= vt[i]:
vc[i] = vt[i]
vt[i] = 0
ac[i] = 0
else:
if vc[i] + ac[i] < m1[i]:
vc[i] = m1[i]
else:
vc[i] = vc[i] + ac[i]
if v > vt[i] and dc[i] !=0 : # decelerate
if v - dc[i] <= vt[i]:
vc[i] = vt[i]
vt[i] = 0
dc[i] = 0
else:
vc[i] = vc[i] - dc[i]
if vc[i] < m2[i]: # if target < minimum pulse => target = min
vc[i] = 0
vt[i] = 0
dc[i] = 0
if vc[i] != vp[i]:
vp[i] = vc[i]
set_pwm()
def display_control(x):
global lcd, ch, sig
global vc, dac, ddc, vt, ac, dc, di, dt, m1, m2, vp, cja, cjd
display_ch()
display_big_numbers(vc[ch])
timer0=Timer()
timer2=Timer()
timer4=Timer()
timer0.init(freq=2, callback=running)
timer2.init(freq=10, callback=speed_control)
timer4.init(freq=2, callback=display_control)
print ('*************************************')
print ('** **')
print ('** Test de commande externe **')
print ('** (dans ce cas, via le clavier) **')
print ('** **')
print ('*************************************')
di[0] = 1
dt[0] = 1
# set_speed(number=0, speed=0, acceleration=10, deceleration=12, direction=0)
while 1:
if dt[0] == 1:
print ('*** Marche avant ***')
else:
print ('*** Marche arrière ***')
print ('Taper <enter> pour démarrer et accélérer')
input()
set_speed(speed=400, acceleration=10)
print ('Taper <enter> pour freiner et arrêter')
input()
set_speed(speed=0, deceleration=10)
print ("Taper <enter> pour recommencer dans l'autre sens")
input()
dt[0] = dt[0] * -1 # target direction
set_speed(direction=dt[0])
Bibliothèque à importer : ssd1306.py
# MicroPython SSD1306 OLED driver, I2C and SPI interfaces
from micropython import const
import framebuf
# register definitions
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xA4)
SET_NORM_INV = const(0xA6)
SET_DISP = const(0xAE)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xA0)
SET_MUX_RATIO = const(0xA8)
SET_COM_OUT_DIR = const(0xC0)
SET_DISP_OFFSET = const(0xD3)
SET_COM_PIN_CFG = const(0xDA)
SET_DISP_CLK_DIV = const(0xD5)
SET_PRECHARGE = const(0xD9)
SET_VCOM_DESEL = const(0xDB)
SET_CHARGE_PUMP = const(0x8D)
# Subclassing FrameBuffer provides support for graphics primitives
# http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
class SSD1306(framebuf.FrameBuffer):
def __init__(self, width, height, external_vcc):
self.width = width
self.height = height
self.external_vcc = external_vcc
self.pages = self.height // 8
self.buffer = bytearray(self.pages * self.width)
super().__init__(self.buffer, self.width, self.height, framebuf.MONO_VLSB)
self.init_display()
def init_display(self):
for cmd in (
SET_DISP | 0x00, # off
# address setting
SET_MEM_ADDR,
0x00, # horizontal
# resolution and layout
SET_DISP_START_LINE | 0x00,
SET_SEG_REMAP | 0x01, # column addr 127 mapped to SEG0
SET_MUX_RATIO,
self.height - 1,
SET_COM_OUT_DIR | 0x08, # scan from COM[N] to COM0
SET_DISP_OFFSET,
0x00,
SET_COM_PIN_CFG,
0x02 if self.width > 2 * self.height else 0x12,
# timing and driving scheme
SET_DISP_CLK_DIV,
0x80,
SET_PRECHARGE,
0x22 if self.external_vcc else 0xF1,
SET_VCOM_DESEL,
0x30, # 0.83*Vcc
# display
SET_CONTRAST,
0xFF, # maximum
SET_ENTIRE_ON, # output follows RAM contents
SET_NORM_INV, # not inverted
# charge pump
SET_CHARGE_PUMP,
0x10 if self.external_vcc else 0x14,
SET_DISP | 0x01,
): # on
self.write_cmd(cmd)
self.fill(0)
self.show()
def poweroff(self):
self.write_cmd(SET_DISP | 0x00)
def poweron(self):
self.write_cmd(SET_DISP | 0x01)
def contrast(self, contrast):
self.write_cmd(SET_CONTRAST)
self.write_cmd(contrast)
def invert(self, invert):
self.write_cmd(SET_NORM_INV | (invert & 1))
def show(self):
x0 = 0
x1 = self.width - 1
if self.width == 64:
# displays with width of 64 pixels are shifted by 32
x0 += 32
x1 += 32
self.write_cmd(SET_COL_ADDR)
self.write_cmd(x0)
self.write_cmd(x1)
self.write_cmd(SET_PAGE_ADDR)
self.write_cmd(0)
self.write_cmd(self.pages - 1)
self.write_data(self.buffer)
class SSD1306_I2C(SSD1306):
def __init__(self, width, height, i2c, addr=0x3C, external_vcc=False):
self.i2c = i2c
self.addr = addr
self.temp = bytearray(2)
self.write_list = [b"\x40", None] # Co=0, D/C#=1
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.temp[0] = 0x80 # Co=1, D/C#=0
self.temp[1] = cmd
self.i2c.writeto(self.addr, self.temp)
def write_data(self, buf):
self.write_list[1] = buf
self.i2c.writevto(self.addr, self.write_list)
class SSD1306_SPI(SSD1306):
def __init__(self, width, height, spi, dc, res, cs, external_vcc=False):
self.rate = 10 * 1024 * 1024
dc.init(dc.OUT, value=0)
res.init(res.OUT, value=0)
cs.init(cs.OUT, value=1)
self.spi = spi
self.dc = dc
self.res = res
self.cs = cs
import time
self.res(1)
time.sleep_ms(1)
self.res(0)
time.sleep_ms(10)
self.res(1)
super().__init__(width, height, external_vcc)
def write_cmd(self, cmd):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs(1)
self.dc(0)
self.cs(0)
self.spi.write(bytearray([cmd]))
self.cs(1)
def write_data(self, buf):
self.spi.init(baudrate=self.rate, polarity=0, phase=0)
self.cs(1)
self.dc(1)
self.cs(0)
self.spi.write(buf)
self.cs(1)
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