# Cytron Maker Pi RP2040 Ping Servo Meter Bot

This robot works very similar to our standard CoderDojo Collision Avoidance Robot. However it adds a 180 degree servo to show the distance to the object in front of it. It also uses a OLED display to present instructions and display the distance to the object.

This program was contributed by Joe Glenn for the Minneapolis Bakken Museum Droid December event in December 2021.

## Test Servo

This program tests the servo by sweeping the angle from 0 to 180 and back.

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40``` ``````# servo sweep test # Brown: GND # Orange/Red : VCC # Yellow: Signal # # Time for high level (Radio Shack Micro-servo @ 5V) # 0.5 ms : 0 degree # 1.0 ms : 45 degree # 1.5 ms : 90 degree # 2.0 ms : 135 degree # 2.5 ms : 180 degree from machine import Pin, PWM from time import sleep SERVO_PIN = 15 servoPin = PWM(Pin(SERVO_PIN)) servoPin.freq(50) def servo(degrees): if degrees > 180: degrees=180 if degrees < 0: degrees=0 maxDuty=8000 # duty*100 minDuty=2000 # duty*100 #maxDuty=2000 # test #minDuty=8000 # test newDuty=minDuty+(maxDuty-minDuty)*(degrees/180) servoPin.duty_u16(int(newDuty)) while True: for degree in range(0,180,1): servo(degree) sleep(0.01) print("increasing -- "+str(degree)) for degree in range(180, 0, -1): servo(degree) sleep(0.01) print("decreasing -- "+str(degree)) ``````

## Main Python Code

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453``` ``````# Demo for Maker Pi RP2040 board using Ping sensor, servo and i2c display from machine import Pin, PWM, Timer import utime import urandom from ssd1306 import SSD1306_I2C from neopixel import Neopixel from machine import Pin, I2C from ssd1306 import SSD1306_I2C import framebuf import math import utime # # Ping Sensor # Use the Grove 4 Connector and put trigger on white and echo on yellow # PING_TRIGGER_PIN = 7 # GP7 PING_ECHO_PIN = 28 # GP28 # # i2c OLED 128x32 # OLED_SDA_PIN = 26 # GP26 OLED_SCL_PIN = 27 # GP27 # # Servo # GND: Brown # VCC: Orange/Red # GP15 Yellow: Signal # # Time for high level (Radio Shack Micro-servo @ 5V) # 0.5 ms : 0 degree # 1.0 ms : 45 degree # 1.5 ms : 90 degree # 2.0 ms : 135 degree # 2.5 ms : 180 degree SERVO_PIN = 15 # IQR Pins FASTER_PIN = 20 SLOWER_PIN = 21 # built-in Buzzer BUZZER_PIN = 22 # Adjust these parameters to tune the collision avoidance behavior POWER_LEL = 35000 TURN_DISTANCE = 20 # distance we decide to turn - try 20 REVERSE_TIME = .4 # how long we backup TURN_TIME = .4 # how long we turn # startup mode is 0 - motors off and LEDs flashing # mode 1 is slow # mode 2 is medium # mode 3 is fast mode = 0 # Init HC-SR04P pins trigger = Pin(PING_TRIGGER_PIN, Pin.OUT) # send trigger out to sensor echo = Pin(PING_ECHO_PIN, Pin.IN) # get the delay interval back faster_pin = machine.Pin(FASTER_PIN, machine.Pin.IN, machine.Pin.PULL_DOWN) slower_pin = machine.Pin(SLOWER_PIN, machine.Pin.IN, machine.Pin.PULL_DOWN) last_time = 0 # the last time we pressed the button # # DISPLAY STUFF # # Display Image & text on I2C driven ssd1306 OLED display WIDTH = 128 # oled display width HEIGHT = 32 # oled display height # Explicit Method sda=machine.Pin(OLED_SDA_PIN) scl=machine.Pin(OLED_SCL_PIN) i2c=machine.I2C(1,sda=sda, scl=scl, freq=40000) # 400k is too fast and has issues print( 'i2c={:02X}'.format( i2c.scan()[0] ) ) #print(help(i2c)) #print(help(i2c.init)) #print(help(i2c.scan)) #print(help(i2c.start)) #print(help(i2c.stop)) #print(help(i2c.readinto)) #print(help(i2c.write)) #print(help(i2c.readfrom)) #print(help(i2c.readfrom_into)) #print(help(i2c.writeto)) #print(help(i2c.writevto)) #print(help(i2c.readfrom_mem)) #print(help(i2c.readfrom_mem_into)) #print(help(i2c.writeto_mem)) #exit oled = SSD1306_I2C(128, 32, i2c) # Raspberry Pi logo as 32x32 bytearray buffer = bytearray(b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00|?\x00\x01\x86@\x80\x01\x01\x80\x80\x01\x11\x88\x80\x01\x05\xa0\x80\x00\x83\xc1\x00\x00C\xe3\x00\x00~\xfc\x00\x00L'\x00\x00\x9c\x11\x00\x00\xbf\xfd\x00\x00\xe1\x87\x00\x01\xc1\x83\x80\x02A\x82@\x02A\x82@\x02\xc1\xc2@\x02\xf6>\xc0\x01\xfc=\x80\x01\x18\x18\x80\x01\x88\x10\x80\x00\x8c!\x00\x00\x87\xf1\x00\x00\x7f\xf6\x00\x008\x1c\x00\x00\x0c \x00\x00\x03\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00") # Load the raspberry pi logo into the framebuffer (the image is 32x32) fb = framebuf.FrameBuffer(buffer, 32, 32, framebuf.MONO_HLSB) def blk(): oled.fill(0) oled.show() def horiz(l,t,r,c): # left, right , top n = r-l+1 # Horizontal line for i in range(n): oled.pixel(l + i, t, c) def vert(l,t,b,c): # left, top, bottom n = b-t+1 # Vertical line for i in range(n): oled.pixel(l, t+i,c) def box(l,t,r,b,c): # left, top, right, bottom horiz(l,t,r,c) # Hollow rectangle horiz(l,b,r,c) vert(l,t,b,c) vert(r,t,b,c) def ring2(cx,cy,r,c): # Centre (x,y), radius, colour for angle in range(0, 90, 2): # 0 to 90 degrees in 2s y3=int(r*math.sin(math.radians(angle))) x3=int(r*math.cos(math.radians(angle))) oled.pixel(cx-x3,cy+y3,c) # 4 quadrants oled.pixel(cx-x3,cy-y3,c) oled.pixel(cx+x3,cy+y3,c) oled.pixel(cx+x3,cy-y3,c) #print(help(oled.text())) #print(help()) #help('modules') #help(oled) #help(oled.text) #help(framebuf.FrameBuffer) #help(framebuf.FrameBuffer.help()) # Clear the oled display in case it has junk on it. oled.fill(0) # Black # Blit the image from the framebuffer to the oled display oled.blit(fb, 96, 0) # Basic stuff oled.text("Raspberry Pi",5,5) oled.text("RP2040",5,15) oled.text("press GP21",5,25) oled.pixel(10,60,1) #ring2(50,43,20,1) # Empty circle # Finally update the oled display so the image & text is displayed oled.show() utime.sleep(1) # # Back to the motor control stuff. (sorry... i'm soppy today) # # This function gets called every time the button is pressed. The parameter "pin" is not used. def button_pressed_handler(pin): global mode, last_time new_time = utime.ticks_ms() # if it has been more that 1/5 of a second since the last event, we have a new event if (new_time - last_time) > 200: # this should be pin.id but it does not work if '21' in str(pin): mode +=1 else: mode -=1 # deal with ends if mode > 4: mode = 2 if mode < 0: mode = 0 last_time = new_time # now we register the handler function when the button is pressed faster_pin.irq(trigger=machine.Pin.IRQ_FALLING, handler = button_pressed_handler) slower_pin.irq(trigger=machine.Pin.IRQ_FALLING, handler = button_pressed_handler) # Piezo Buzzer is on GP22 buzzer=PWM(Pin(BUZZER_PIN)) MAX_POWER_LEVEL = 65025 MAX_DISTANCE = 100 # ignore anything above this # Motor Pins are A: 8,9 and B: 10,11 RIGHT_FORWARD_PIN = 11 # this must be wired backword? RIGHT_REVERSE_PIN = 10 LEFT_FORWARD_PIN = 9 LEFT_REVERSE_PIN = 8 # our PWM objects right_forward = PWM(Pin(RIGHT_FORWARD_PIN)) right_reverse = PWM(Pin(RIGHT_REVERSE_PIN)) left_forward = PWM(Pin(LEFT_FORWARD_PIN)) left_reverse = PWM(Pin(LEFT_REVERSE_PIN)) # returns distance in cm def ping(): #print('in ping') trigger.low() utime.sleep_us(2) # Wait 2 microseconds low trigger.high() utime.sleep_us(5) # Stay high for 5 miroseconds trigger.low() while echo.value() == 0: signaloff = utime.ticks_us() #print('echo is 1') while echo.value() == 1: signalon = utime.ticks_us() timepassed = signalon - signaloff distance = (timepassed * 0.0343) / 2 print(distance) return int(distance) def turn_motor_on(pwm): #pwm.duty_u16(65025) pwm.duty_u16(16000) def turn_motor_off(pwm): pwm.duty_u16(0) def forward(): turn_motor_on(right_forward) turn_motor_on(left_forward) turn_motor_off(right_reverse) turn_motor_off(left_reverse) def reverse(): turn_motor_on(right_reverse) turn_motor_on(left_reverse) turn_motor_off(right_forward) turn_motor_off(left_forward) def turn_right(): turn_motor_on(right_forward) turn_motor_on(left_reverse) turn_motor_off(right_reverse) turn_motor_off(left_forward) def turn_left(): turn_motor_on(right_reverse) turn_motor_on(left_forward) turn_motor_off(right_forward) turn_motor_off(left_reverse) def stop(): turn_motor_off(right_forward) turn_motor_off(right_reverse) turn_motor_off(left_forward) turn_motor_off(left_reverse) # The Maker Pi RP2040 has 13 fantastic blue GPIO status LEDs blue_led_pins = [0, 1, 2, 3, 4, 5, 6, 7, 26, 27, 28] blue_led_pins.remove(PING_TRIGGER_PIN) blue_led_pins.remove(PING_ECHO_PIN) blue_led_pins.remove(OLED_SDA_PIN) blue_led_pins.remove(OLED_SCL_PIN) # dist_scale = [2, 4, 6, 8, 10, 13, 16, 20, 25, 35, 50, 75, 100] dist_scale = [2, 4, 6, 8, 10, 15, 20, 25, 50, 100, 150, 200, 300] NUMBER_PIXELS = 2 STATE_MACHINE = 0 NEOPIXEL_PIN = 18 # The Neopixels on the Maker Pi RP2040 are the GRB variety, not RGB strip = Neopixel(NUMBER_PIXELS, STATE_MACHINE, NEOPIXEL_PIN, "GRB") strip.brightness(100) number_leds = len(blue_led_pins) led_ports = [] red = (255, 0, 0) orange = (255, 60, 0) # Gamma corrected from G=128 to be less like yellow yellow = (255, 150, 0) green = (0, 255, 0) blue = (0, 0, 255) indigo = (75, 0, 130) # purple? violet = (138, 43, 226) # mostly pink cyan = (0, 255, 255) lightgreen = (100, 255, 100) white = (128, 128, 128) # not too bright pink = (255, 128, 128) color_names = ('red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet', 'cyan', 'lightgreen', 'white') num_colors = len(color_names) colors = (red, orange, yellow, green, blue, indigo, violet, cyan, lightgreen, white, pink) # create a list of the ports for i in range(number_leds): led_ports.append(machine.Pin(blue_led_pins[i], machine.Pin.OUT)) LED_DELAY = .08 def run_lights(): for i in range(0, number_leds): led_ports[i].high() strip.set_pixel(0, colors[i]) strip.set_pixel(1, colors[i]) strip.show() utime.sleep(LED_DELAY) led_ports[i].low() # blue down for i in range(number_leds - 1, 0, -1): led_ports[i].high() strip.set_pixel(0, colors[i]) strip.set_pixel(1, colors[i]) strip.show() utime.sleep(LED_DELAY) led_ports[i].low() def led_show_dist(in_distance): global number_leds for led_index in range(0, number_leds): if in_distance > dist_scale[led_index]: led_ports[led_index].high() else: led_ports[led_index].low() def play_no_signal(): playnote(100, 0.1) sound_off() def play_turn(): playnote(500, .1) sound_off() def setfreq(frequency): buzzer.freq(frequency) def playnote(frequency, time): buzzer.duty_u16(1000) setfreq(frequency) utime.sleep(time) def sound_off(): buzzer.duty_u16(0) def rest(time): buzzer.duty_u16(0) utime.sleep(time) def play_startup(): playnote(600, .2) rest(.05) playnote(600, .2) rest(.05) playnote(600, .2) rest(.1) playnote(800, .4) sound_off() def servo(degrees): if degrees > 180: degrees=180 if degrees < 0: degrees=0 maxDuty=8000 # duty*100 minDuty=2000 # duty*100 #maxDuty=2000 # test #minDuty=8000 # test newDuty=minDuty+(maxDuty-minDuty)*(degrees/180) servoPin.duty_u16(int(newDuty)) servoPin = PWM(Pin(SERVO_PIN)) servoPin.freq(50) valid_distance = 1 def main(): global valid_distance print("running main()") play_startup() oled_count=0 # repeat every oled_count_max=0 # times through loop servo_count=0 servo_count_max=0 # when to update servo_degrees = 0 servo(servo_degrees) # start in that pos # loop forever while True: if mode == 0: stop() run_lights() else: distance = ping() print('Distance:', distance) oled_count += 1 if oled_count > oled_count_max: oled.fill(0) # Black oled.text("Distance:",5,5) oled.text("{:f}".format(distance),5,15) oled.show() oled_count = 0 servo_count += 1 if servo_count > servo_count_max: if distance > MAX_DISTANCE: servo_degrees = 0 else: servo_degrees = 180-distance/MAX_DISTANCE*180 servo(servo_degrees) servo_count = 0 if distance > MAX_DISTANCE: # only print if we used to have a valid distance if valid_distance == 1: print('no signal') valid_distance = 0 else: print(distance) #note=distance*10 #playnote(note, .025) if distance < TURN_DISTANCE: play_turn() # back up for a bit reverse() utime.sleep(REVERSE_TIME) # half right and half left turns if urandom.random() < .5: turn_right() else: turn_left() utime.sleep(TURN_TIME) forward() else: print('forward') forward() valid_distance = 1 led_show_dist(distance) utime.sleep(0.05) # clean up # This allows us to stop the sound and motors when we do a Stop or Control-C which is a keyboard interrupt try: main() except KeyboardInterrupt: print('Got ctrl-c') except Exception as e: print(e) finally: # Optional cleanup code print('turning off sound') buzzer.duty_u16(0) print('shutting motors down') stop() ``````