I made a full color POV display using SPRESENSE and DotStar LED tape.

Constitution

LED tape, SPRESENSE and reflectance sensor are mounted on the rotating part, and LED tape uses DotStar. Using the wireless charging module, the power supply to the rotating part was carried out wirelessly.

One AA battery was used for the motor and three AA batteries for the wireless power supply to the rotating part.

Parts

Sony SPRESENSE
　
SPRESENSE Mini Extension Board KASPI001

KASPI001基板
功力製作所
QTR-1A Reflectance Sensor
Adafruit DotStar Digital LED Strip
DFRobot Wireless Charging Module 5V/1A

《お取り寄せ商品》Wireless Charging Module 5V/1A - スイッチサイエンス
スイッチサイエンス
DC Motor RS-540SH
SparkFun Voltage-Level Translator TXB0104

POV Display Device

The motor was fixed with metal fittings and the handle was made with black wood, and the battery socket and power supply on/off slide switch were fixed.

The rotating part is completely independent as follows.

I used two Dotstar LED tapes. 29 cells LED tape is controlled by SPI4. 28 cells LED tape is controlled by SPI5.

I spread a milky film for the diffusion of light.

Voltage-Level Translator TXB0104 is used to convert the logic level of SPRESENSE from 1.8V to 5V.

I used the wireless charge module for power supply to the LED rotating part. It is only placed in the face-through the transmission coil to the rotation axis of the motor without almost processing.

Arduino IDE Code

The following libraries are used for Dotstar.
　https://github.com/adafruit/Adafruit_DotStar

Adafruit_DotStar_SPI5.h is a modification of Adafruit_DotStar.h to use SPI5.

When a reflectance sensor detects a marker, it decreases the output, so it detects it in the attachinterrupt and measures the time it takes to interrupt processing by one lap.

It switches the LED blink by dividing the time of one lap by 150. LED display patterns are stored as an array in graphics.h.

#include <SPI.h> 
#include "Adafruit_DotStar_SPI5.h"
#include <Adafruit_DotStar.h>
#include "graphics.h"
#define NUMPIXELS2 29 // Number of LEDs in strip
#define NUMPIXELS 57 // Number of LEDs in 2 strips
#define Frame 16
#define Div 150
#define Fclk 26000000
#define itrPin 19

int numRot = 0;
int numDiv = 0, numDiv2 = 0; 
int stateDiv = 0;

unsigned long rotTime, timeOld, timeNow;

Adafruit_DotStar_SPI5 strip5 = Adafruit_DotStar_SPI5(NUMPIXELS2, DOTSTAR_BGR);

Adafruit_DotStar strip4 = Adafruit_DotStar(NUMPIXELS2, DOTSTAR_BGR);


void setup() {
 Serial.begin(115200);
 strip5.begin();
 SPI5.beginTransaction(SPISettings(Fclk, MSBFIRST, SPI_MODE0));
 strip4.begin();
 SPI.beginTransaction(SPISettings(Fclk, MSBFIRST, SPI_MODE0));
 strip5.clear();
 strip4.clear();
 strip5.show();
 strip4.show();
 delay(500);
 attachInterrupt(digitalPinToInterrupt(itrPin), RotCount, FALLING );
}

void loop() {
 if(stateDiv == 1 && micros() - timeOld > rotTime / Div * (numDiv)){
   stateDiv = 0;
 }

 if(stateDiv == 0 && micros() - timeOld < rotTime / Div * (numDiv + 1)){
   stateDiv = 1;
   strip5.clear();
   strip4.clear();
   for(int i=0;i<NUMPIXELS2; i++){
     numDiv2 = numDiv+2;
     if(numDiv2 >= Div) numDiv2 -= Div;
     strip5.setPixelColor(i, pic[numRot][numDiv2][i*2]);
     strip4.setPixelColor(i, pic[numRot][numDiv][i*2+1]);
   }
   strip5.show();
   strip4.show();
   numDiv++;
   if(numDiv >= Div ) numDiv = 0;
 }
}

void RotCount() {
 timeNow = micros();
 rotTime = timeNow - timeOld;
 timeOld = timeNow;
 numRot++;
 if(numRot >= Frame) numRot = 0;
}

#include <SPI.h>

#include "Adafruit_DotStar_SPI5.h"

#include <Adafruit_DotStar.h>

#include "graphics.h"

#define NUMPIXELS2 29 // Number of LEDs in strip

#define NUMPIXELS 57 // Number of LEDs in 2 strips

#define Frame 16

#define Div 150

#define Fclk 26000000

#define itrPin 19

int numRot = 0;

int numDiv = 0, numDiv2 = 0;

int stateDiv = 0;

unsigned long rotTime, timeOld, timeNow;

Adafruit_DotStar_SPI5 strip5 = Adafruit_DotStar_SPI5(NUMPIXELS2, DOTSTAR_BGR);

Adafruit_DotStar strip4 = Adafruit_DotStar(NUMPIXELS2, DOTSTAR_BGR);

void setup() {

Serial.begin(115200);

strip5.begin();

SPI5.beginTransaction(SPISettings(Fclk, MSBFIRST, SPI_MODE0));

strip4.begin();

SPI.beginTransaction(SPISettings(Fclk, MSBFIRST, SPI_MODE0));

strip5.clear();

strip4.clear();

strip5.show();

strip4.show();

delay(500);

attachInterrupt(digitalPinToInterrupt(itrPin), RotCount, FALLING );

}

void loop() {

if(stateDiv == 1 && micros() - timeOld > rotTime / Div * (numDiv)){

stateDiv = 0;

}

if(stateDiv == 0 && micros() - timeOld < rotTime / Div * (numDiv + 1)){

stateDiv = 1;

strip5.clear();

strip4.clear();

for(int i=0;i<NUMPIXELS2; i++){

numDiv2 = numDiv+2;

if(numDiv2 >= Div) numDiv2 -= Div;

strip5.setPixelColor(i, pic[numRot][numDiv2][i*2]);

strip4.setPixelColor(i, pic[numRot][numDiv][i*2+1]);

}

strip5.show();

strip4.show();

numDiv++;

if(numDiv >= Div ) numDiv = 0;

}

void RotCount() {

timeNow = micros();

rotTime = timeNow - timeOld;

timeOld = timeNow;

numRot++;

if(numRot >= Frame) numRot = 0;

}

Display Graphic Data Creation Method (Python)

Create POV display data “graphics.h” in Python Code. Display data can be created from GIF or still images.

# -*- coding: utf-8 -*-
import cv2
import os
import math
from PIL import Image

#Array setting
NUMPIXELS = 57 #Number of LEDs
Div = 150 #Number of divisions per lap
Bright = 30 #LED Brightness 
Led0Bright = 3 #Brightness of center LED [%]

#File creation
file = open('graphics.h', 'w')
file.write('#define NUMPIXELS ' + str(NUMPIXELS) + '\n')
file.write('#define Div ' + str(Div) + '\n' + '\n')
#file.write('#define Frame ' + str(Frame) + '\n' + '\n')
file.write('const uint32_t pic [Frame][Div][NUMPIXELS] = {' + '\n')

# Read GIF file
gif_file_name = "xxx.gif"
gif = cv2.VideoCapture(gif_file_name)
#Image conversion function
def polarConv(pic, i):
   imgOrgin = cv2.imread(pic) #Read image data
   h, w, _ = imgOrgin.shape #Get image size
   #Image reduction
   imgRedu = cv2.resize(imgOrgin,(math.floor((NUMPIXELS * 2 -1)/h *w), NUMPIXELS * 2 -1))
   #cv2.imwrite(str(i) + '-resize.jpg',imgRedu)
   #Reduced image center coordinates
   h2, w2, _ = imgRedu.shape
   wC = math.floor(w2 / 2)
   hC = math.floor(h2 / 2)
   #Polar coordinate conversion image preparation
   imgPolar = Image.new('RGB', (NUMPIXELS, Div))
   #Polar transformation
   file.write('\t{\n')
   for j in range(0, Div):
       file.write('\t\t{')
       for i in range(0, hC+1):
           #Get coordinate color
           rP = int(imgRedu[hC + math.ceil(i * math.cos(2*math.pi/Div*j)),
                        wC - math.ceil(i * math.sin(2*math.pi/Div*j)), 2]
                    * ((100 - Led0Bright) / NUMPIXELS * i + Led0Bright) / 100 * Bright /100)
           gP = int(imgRedu[hC + math.ceil(i * math.cos(2*math.pi/Div*j)),
                        wC - math.ceil(i * math.sin(2*math.pi/Div*j)), 1]
                    * ((100 - Led0Bright) / NUMPIXELS * i + Led0Bright) / 100 * Bright /100)
           bP = int(imgRedu[hC + math.ceil(i * math.cos(2*math.pi/Div*j)),
                        wC - math.ceil(i * math.sin(2*math.pi/Div*j)), 0]
                    * ((100 - Led0Bright) / NUMPIXELS * i + Led0Bright) / 100 * Bright /100)
           file.write('0x%02X%02X%02X' % (rP,gP,bP))
           if i == hC:
               file.write('},\n')
           else:
               file.write(', ')
           imgPolar.putpixel((i,j), (rP, gP, bP))
   file.write('\t},\n\n')

#Generate directory to save screen capture
dir_name = "screen_caps"
if not os.path.exists(dir_name):
   os.mkdir(dir_name)
i = 0
while True:
   is_success, frame = gif.read()
   # Exit when the file can not be read
   if not is_success:
       break
   # Write out to an image file
   img_name = str(i) + ".jpg"
   img_path = os.path.join(dir_name, img_name)
   cv2.imwrite(img_path, frame)
   #conversion
   polarConv(img_path, i)
   i += 1
file.write('};' + '\n' + '\n')
file.close()

#Inserting the number of frames at the beginning of the file
with open('graphics.h') as f:
   l = f.readlines()
l.insert(0, '#define Frame ' + str(i) + '\n')
with open('graphics.h', mode='w') as f:
   f.writelines(l)

# -*- coding: utf-8 -*-

import cv2

import os

import math

from PIL import Image

#Array setting

NUMPIXELS = 57 #Number of LEDs

Div = 150 #Number of divisions per lap

Bright = 30 #LED Brightness

Led0Bright = 3 #Brightness of center LED [%]

#File creation

file = open('graphics.h', 'w')

file.write('#define NUMPIXELS ' + str(NUMPIXELS) + '\n')

file.write('#define Div ' + str(Div) + '\n' + '\n')

#file.write('#define Frame ' + str(Frame) + '\n' + '\n')

file.write('const uint32_t pic [Frame][Div][NUMPIXELS] = {' + '\n')

# Read GIF file

gif_file_name = "xxx.gif"

gif = cv2.VideoCapture(gif_file_name)

#Image conversion function

def polarConv(pic, i):

imgOrgin = cv2.imread(pic) #Read image data

h, w, _ = imgOrgin.shape #Get image size

#Image reduction

imgRedu = cv2.resize(imgOrgin,(math.floor((NUMPIXELS * 2 -1)/h *w), NUMPIXELS * 2 -1))

#cv2.imwrite(str(i) + '-resize.jpg',imgRedu)

#Reduced image center coordinates

h2, w2, _ = imgRedu.shape

wC = math.floor(w2 / 2)

hC = math.floor(h2 / 2)

#Polar coordinate conversion image preparation

imgPolar = Image.new('RGB', (NUMPIXELS, Div))

#Polar transformation

file.write('\t{\n')

for j in range(0, Div):

file.write('\t\t{')

for i in range(0, hC+1):

#Get coordinate color

rP = int(imgRedu[hC + math.ceil(i * math.cos(2*math.pi/Div*j)),

wC - math.ceil(i * math.sin(2*math.pi/Div*j)), 2]

* ((100 - Led0Bright) / NUMPIXELS * i + Led0Bright) / 100 * Bright /100)

gP = int(imgRedu[hC + math.ceil(i * math.cos(2*math.pi/Div*j)),

wC - math.ceil(i * math.sin(2*math.pi/Div*j)), 1]

* ((100 - Led0Bright) / NUMPIXELS * i + Led0Bright) / 100 * Bright /100)

bP = int(imgRedu[hC + math.ceil(i * math.cos(2*math.pi/Div*j)),

wC - math.ceil(i * math.sin(2*math.pi/Div*j)), 0]

* ((100 - Led0Bright) / NUMPIXELS * i + Led0Bright) / 100 * Bright /100)

file.write('0x%02X%02X%02X' % (rP,gP,bP))

if i == hC:

file.write('},\n')

else:

file.write(', ')

imgPolar.putpixel((i,j), (rP, gP, bP))

file.write('\t},\n\n')

#Generate directory to save screen capture

dir_name = "screen_caps"

if not os.path.exists(dir_name):

os.mkdir(dir_name)

i = 0

while True:

is_success, frame = gif.read()

# Exit when the file can not be read

if not is_success:

break

# Write out to an image file

img_name = str(i) + ".jpg"

img_path = os.path.join(dir_name, img_name)

cv2.imwrite(img_path, frame)

#conversion

polarConv(img_path, i)

i += 1

file.write('};' + '\n' + '\n')

file.close()

#Inserting the number of frames at the beginning of the file

with open('graphics.h') as f:

l = f.readlines()

l.insert(0, '#define Frame ' + str(i) + '\n')

with open('graphics.h', mode='w') as f:

f.writelines(l)

Test GIF File

I used the following GIF file. The number of frames is 16.

Operation

ミニ拡張ボードが本日届き SPI4とSPI5でLEDテープ2本制御できた。回転方向の分解能は70/周で外付けのレベルシフタで律速。明日高速レベルシフタが届くので回転方向の高分解能化にも期待したい。あとSDにデータ持って長編表示も試したい。https://t.co/h0IIR7E7cB #SPRESENSE #GIF #POVディスプレイ pic.twitter.com/1MaKvrBBAb

— HomeMadeGarbage (@H0meMadeGarbage) 2019年2月15日

Holographic display could be easily realized using SPRESENSE with two SPI outputs at high speed.

「POV Display Using SPRESENSE」への1件のフィードバック

Jackie より:

2020年6月16日 11:17 AM

Hello – great project. I would like to recreate this using my own images but I have a few questions.
– why did you use spresence? Is there a cheaper, but equally as good microcontroller I could use?
– when you say “the Adafruit_DotStar_SPI5.h is a modification of Adafruit_DotStar.h to use SPI5” what change did you make?
I hope you don’t mind me asking – I really want to make this for a group of artists in the US for demonstration and I might have more questions as I am really a beginner.
Thanks, jackie

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Constitution

Parts

POV Display Device

Arduino IDE Code

Display Graphic Data Creation Method (Python)

Test GIF File

Operation

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「POV Display Using SPRESENSE」への1件のフィードバック

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