DIY Electronics

Animation using a Seeeduino xiao and Oled 128x64

To display images on an Oled 128x64 I made 128x64 pixels BMP images with Photoshop. The BMP file has to be converted into a hex file, readable by the microcontroller. Every pixel is a bit. The first byte of 8-bits represents the first 8 pixels in the first column, second byte are the 8 pixels in the second column. There are 16 bytes for each column and 64 bytes for each row. A c# program converts the BMP to Hex. I added a tiny boost converter to raise the voltage from 1.5v to 5v, so it can run on a AAA battery.

Source code Seeeduino Arduino IDE

source code for lalinea

Convert BMP to Hex using c#

Seeeduino Xiao - HID device to emulate keyboard

This website shows how to use seeeduino xiao with Adafruit_TinyUSb library to emulate keyboard strokes.
When seeeduino is inserted into USB port it will run the code.
The code starts "cmd" from Windows+R run box and connects to sever using FTP and uploads files, then it starts putty, connects to the server and logs in.
I put a digitalRead on pin 4 just to have a part of the code run. Pin 4 is connect to a push button to ground (not shown in the picture).
pinMode(4, INPUT_PULLUP) seems to work.
Initially I got this error when uploading the code: Adafruit_USBD_HID does not name a type; did you mean Adafruit_USBD_CDC?
The cause was two libraries with the same name Adafruit_TinyUSB_arduino; one in arduino/libraries and the other one in ..\AppData\Local\Arduino15\packages\Seeeduino\hardware\samd\1.8.5\libraries.
Then there was the return-key error. I used #define KEY_RETURN 40 to fix the problem.

8 queens problem in Python

import sys

#-------------------------------------------------
def backtrack():    # curr_col == 8
    
    global curr_row
    global curr_col
    
    board[curr_row][7] = ' ' # remove queens from last row
    curr_row -= 1            # down one row
    if (curr_row < 0):
        end_of_the_game("row number less than 0 (zero)")
    curr_col = queens[curr_row]         # get col value from queens
    board[curr_row][curr_col] = ' '     # clean board from this row
    curr_col += 1             # advance col
    if (curr_col == 8):
        backtrack()


#------------------------------------------

def print_board(num):
    for i in range(7,-1,-1):
        print('|', end="")
        print ('|'.join(board[i]), end ="")
        print('|')
    print(f"------------------------------{num}------")
        
#-----------------------------------------------------        
def check_position(row,col):
    for y in [x for x in range(8) if x != col]:  # row check
        if board[row][y] == 'Q':
            #print(row,y)
            return False
    for x in [y for y in range(8) if y != row]: # column check
        if board[x][col] == 'Q':
            #print(row,y)
            return False
    x = row + 1
    y = col + 1
    while (x < 8 and y < 8):  # right & up
         # 1,3    2,4 3,5 4,6 5,7 6,8
         # 3,1    4,2 5,3 6,4 7,5 8,6 
        if board[x][y] == 'Q':
            #print(row,y)
            return False
        x += 1
        y += 1
    x = row - 1
    y = col - 1
    while (x > -1 and y > -1):  # left & down
        if board[x][y] == 'Q':
            #print(row,y)
            return False
        x -= 1
        y -= 1       
    x = row + 1
    y = col - 1
    while (x < 8 and y > -1):  # right & down
        if board[x][y] == 'Q':
            #print(row,y)
            return False
        x += 1
        y -= 1
    x = row - 1
    y = col + 1
    while (x > -1 and y < 8):  # left & up
        if board[x][y] == 'Q':
            #print(row,y)
            return False
        x -= 1
        y += 1
    #print(row,y)
    return True
#-----------------------------------------------
def end_of_the_game(msg):
    print (f"{msg}: exiting")

    sys.exit(0)    


#--------------INIT-----------------------------


curr_row = 0 # start at the first row
curr_col = 0 # start at the first column
board = list() # init
queens = list() # init

for x in range(8):
    board.append([])  #creates new row before populate
    for y in range(8):
        board[x].append(' ')

for x in range(8):
    queens.append(0)

# start here, set row = 0 board[0][0]='Q'
# when row > 7 print board and
# set row = 7 and advance curr_col
# stop when row = -1

queens[curr_row]=0
curr_col = 0
board[curr_row][curr_col] = 'Q'
sol = 0
    
while (True):  # end of game happens in backtrack()



    while (curr_row < 8):
        while (check_position(curr_row,curr_col) == False): # while False advance col
            board[curr_row][curr_col] = ' '
            curr_col += 1
            if (curr_col == 8):
                backtrack()
            
        queens[curr_row]=curr_col
        board[curr_row][curr_col] = 'Q'

        curr_row += 1  # go to next row and check
        curr_col = 0
        # end of while

    sol += 1 # number of solutions
    print_board(sol) # row == 8, col = 0
    # end of while (curr_row < 8)

    curr_row = 7
    curr_col = queens[curr_row]
    board[curr_row][curr_col] = ' '
    curr_col += 1
    if (curr_col == 8):
        backtrack()    
    queens[curr_row]=curr_col
    board[curr_row][curr_col] = 'Q'

Monostable 555 with touch plate