用树莓派 pico w 和墨水屏做一个 mnist-clock

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用 raspberry pico w 和墨水屏做一个 mnist-clock

1. 墨水屏

2. pico w 基本配置

2.1 刷固件

  • https://micropython.org/download/rp2-pico-w/

  • 下载类似rp2-pico-w-20221107-unstable-v1.19.1-616-g5987130af.uf2

  • 首次将 pico w 连接电脑之后，会以U盘形式弹出来，把固件拖进去。

  • 已经刷过固件的，按着板子上的 BOOTTSEL 按钮连接电脑。

重新上电，固件就自动刷好了。

2.2 开发环境 thonny

  • 安装 thonny, scoop install thonny
  • Thonny IED： 打开 ‘运行’ - ‘配置解释器’， 配置一下
  • 运行一下板载的 LED 测试程序：
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from machine import Pin 
import time

led = Pin('LED', Pin.OUT)
while(True):
    led.on()
    time.sleep(1)
    led.off()
    time.sleep(1)

可以看到板载的 LED 在闪烁。

3. 处理 mnist 数据集，保存成二进制文件

  • 由于pico可用的内存有限， thonny中显示仅有 800kb 左右可用？

  • 每个数字的mnist字符为 28x28 = 784 像素， 原始数据集是 0-255 黑白色阶的。

  • 这里我们节省存储空间，将每个像素压缩成以黑、白图像保存，这样每个像素仅占1个bit

  • 那么784个bit需要 784 / 8 = 98 个字节，约 0.1kb

  • 也就是每个数字的 mnist 字符的存储空间为 ~ 0.1kb

  • 选择x_train数据集， 选出中 0-9 每个数字的前 500 个

  • 分别转换成一个 *.bin 文件保存，文件名：font_lib_{0-9}.bin

  • 那么每个*.bin 文件为 48kb，全部 mnist font lib 总共占用 480kb

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#%%
import json
import numpy as np


# 1.load mnist dataset
with np.load('../mnist.npz') as f:
    x_train, y_train = f['x_train'], f['y_train']
    x_test, y_test = f['x_test'], f['y_test']

with open('../mnist_index.json', 'r') as f:
    idx_dict = json.load(f)

#%%
# 2. 将 mnist 打印成字符画
def draw_mnist_num(image):
    bool_array = np.array(image > 128, dtype=int)
    print(bool_array)

    char_array = np.where(image > 128, '@', '-')
    for row in char_array:
        print(''.join(i for i in row))

draw_mnist_num(x_train[0])

#%%
# 3. 将mnist转成2进制字符
def convert_2_hex_str(image):
    # print(image.shape)
    image_bw = image > 128
    image_bit = np.packbits(image_bw)
    # print(image_bit)
    char_2 = image_bit.tobytes()
    # print(char_2)
    return char_2

mm_2 = convert_2_hex_str(x_train[0])
print(len(mm_2), mm_2)

# %% 
# 4. 转成字符数组
def gen_mnist_font_lib_str(m=1):
    font_lib = []

    for num in range(10):
        font = b''
        for idx in idx_dict[str(num)][:m]:
            img = x_train[idx]
            xxx = convert_2_hex_str(img)
            font += xxx

        font_lib.append(font)

    return font_lib


mnist_font_lib = gen_mnist_font_lib_str(500)
print(len(mnist_font_lib))


# 5. 保存
for n, font in enumerate(mnist_font_lib):
    f = open(f'font_lib_{n}.bin', 'wb')
    f.write(font)
    f.close()

4. 先测试下用 pico w 显示 mnist 字符

  • 将生成的 *.bin 文件通过 Thonny 全部上传至 pico w。

  • 测试一下能否正常读取并显示。

4.1 读取 mnist 字符

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# 读取字符，返回一个由 '0' 或 '1' 组成的字符串，字符串长度为784。
def get_mnist_font(num):    
    SIZE = 98
    NUM = 500    
    
    f = open('font_lib_{}.bin'.format(num), 'rb')
    f.seek(random.randrange(0, NUM) * SIZE)
    mf_bin = f.read(SIZE)
    f.close() 
    
    # string: 784 * '0' or '1'
    mf_str = ''.join(['{:08b}'.format(mf_bin[i]) for i in range(SIZE)])
    # mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
 
    return mf_str

4.2 绘制字符 28x28 像素

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# 字符串长度为784，按照 28x28 逐个绘制像素 
def MNIST(draw, mf, i):    
    c0 = [2, 72, 154, 224]
    r0 = [20, 20, 20, 20]

    mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
    for r in range(28):
        for c in range(28):
            color = 0x00 if mf[r*28+c]=='1' else 0xff
            draw.pixel(c + c0[i], r + r0[i], color)

4.3 绘制字符，缩放为 nR x nC 像素

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# 字符串长度为784，按照 nR x nC 逐个绘制像素 
def MNIST(draw, mf, i):    
    c0 = [2, 72, 154, 224]
    r0 = [20, 20, 20, 20]
    nR = 100
    nC = 70

    # resize: 28x28 -> nRxnC
    # mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
    # mf_rsz = [[int(mf_x28[int(28*r/nR)][int(28*c/nC)]) for c in range(nC)] for r in range(nR)]
    for r in range(nR):
        for c in range(nC):
            color = mf[ int(28*r/nR) * 28 + int(28*c/nC) ]
            color = 0x00 if color == '1' else 0xff
            draw.pixel(c + c0[i], r + r0[i], color)

4.4 完整代码

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import random
import time
import Pico_ePaper29 as epd29

import gc
gc.collect()
print("mem: ", gc.mem_free())

# === 1. load mnist font lib
def get_mnist_font(num):
    SIZE = 98
    NUM = 100    
    
    f = open('font_lib_{}.bin'.format(num), 'rb')
    f.seek(random.randrange(0, NUM) * SIZE)
    mf_bin = f.read(SIZE)
    f.close() 
    
    # string: 784 * '0' or '1'
    mf_str = ''.join(['{:08b}'.format(mf_bin[i]) for i in range(SIZE)])
    # mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
 
    return mf_str

# === 2. epaper29: 296x128;     0xff:white;  0x00:black;   
epd = epd29.EPD_2in9_Landscape()
       
def MNIST(draw, mf, i):    
    c0 = [2, 72, 154, 224]
    r0 = [20, 20, 20, 20]
    nR = 100
    nC = 70

    # mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
    # for r in range(28):
    #     for c in range(28):
    #         color = 0x00 if mf[r*28+c]=='1' else 0xff
    #         draw.pixel(c + c0[i], r + r0[i], color)
    
    # resize: 28x28 -> nRxnC
    # mf_rsz = [[int(mf_x28[int(28*r/nR)][int(28*c/nC)]) for c in range(nC)] for r in range(nR)]
    for r in range(nR):
        for c in range(nC):
            color = mf[ int(28*r/nR) * 28 + int(28*c/nC) ]
            color = 0x00 if color == '1' else 0xff
            draw.pixel(c + c0[i], r + r0[i], color)

    gc.collect()
    print(i, "mem: ", gc.mem_free())
    
# --------------------------------------------
print('full update')
epd.Clear(0xff)        
epd.delay_ms(100)
epd.fill(0xff)
epd.delay_ms(100)
epd.display(epd.buffer)
epd.display_Partial(epd.buffer)

last_time = [-1, -1, -1, -1]
now_time = [1, 2, 3, 4]        
for i in range(4):
    if last_time[i] != now_time[i]:
        mnist = get_mnist_font(now_time[i])
        MNIST(epd, mnist, i)

        print('partial update', now_time)
        epd.display_Partial(epd.buffer)
        epd.delay_ms(1000)

gc.collect()
print("mem: ", gc.mem_free())

5. 在墨水屏显示时间

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import network
import random
import time
import ntptime
import Pico_ePaper29 as epd29

# === 0. wifi config ==========================
ssid = 'aaa'
pswd = 'xxx'

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(ssid, pswd)

status = wlan.ifconfig()
print('wifi={}  ip={}'.format(ssid, status[0]))
print(time.localtime())

try:
    # https://www.pool.ntp.org/zone/cn
    ntptime.host = 'cn.pool.ntp.org'
    ntptime.settime()
except Exception as e:
    print('NTPTIME ERROR', e, ntptime.host)

# === 1. load mnist font lib ==================

def get_mnist_font(num):    
    SIZE = 98
    NUM = 100    
    
    f = open('font_lib_{}.bin'.format(num), 'rb')
    f.seek(random.randrange(0, NUM) * SIZE)
    mf_bin = f.read(SIZE)
    f.close() 
    
    # string: 784 * '0' or '1'
    mf_str = ''.join(['{:08b}'.format(mf_bin[i]) for i in range(SIZE)])
    # mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
 
    return mf_str

# === 2. epaper29: 296x128;     0xff:white;  0x00:black;   
epd = epd29.EPD_2in9_Landscape()

def YMD(draw, ymd, wid):
    draw.fill(0xff)
    
    draw.fill_rect(5, 5, 95, 8, 0xff)
    draw.text(wid, 5, 5, 0x00)    
    draw.fill_rect(100, 5, 120, 8, 0xff)
    draw.text(ymd, 100, 5, 0x00)
        
def HMS(draw, txt):
    draw.fill_rect(240, 5, 50, 8, 0xff)
    draw.text(txt, 240, 5, 0x00)

def DOT(draw):
    draw.fill_rect(144, 60, 7, 7, 0x00)
    draw.fill_rect(144, 80, 7, 7, 0x00)

def MNIST(draw, mf, i):    
    c0 = [2, 72, 154, 224]
    r0 = [20, 20, 20, 20]
    nR = 100
    nC = 70

    # mf_x28 = [[mf_str[i*28+j] for j in range(28)] for i in range(28)]
    # for r in range(28):
    #     for c in range(28):
    #         color = 0x00 if mf[r*28+c]=='1' else 0xff
    #         draw.pixel(c + c0[i], r + r0[i], color)
    
    # resize: 28x28 -> nRxnC
    # mf_rsz = [[int(mf_x28[int(28*r/nR)][int(28*c/nC)]) for c in range(nC)] for r in range(nR)]
    for r in range(nR):
        for c in range(nC):
            color = mf[ int(28*r/nR) * 28 + int(28*c/nC) ]
            color = 0x00 if color == '1' else 0xff
            draw.pixel(c + c0[i], r + r0[i], color)
            
def MNIST_clear(draw):
    draw.fill_rect(0, 20, 296, 100, 0xff)
    draw.fill_rect(240, 5, 50, 8, 0xff)
    
# === 3. run ==================================
last_time = [-1, -1, -1, -1]
while (True):
    # 2.1 get time.now
    wifi_id = ssid if wlan.status()==3 else 'no wifi'
    now = time.localtime(time.time() + 8*3600)
    
    year, mon, day = now[0], now[1], now[2]
    hour, mnt, sec = now[3], now[4], now[5]
    week = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
    weekday = week[now[6]]
    now_time = [hour//10, hour%10, mnt//10, mnt%10]
    
    print(now, wifi_id, last_time, now_time)
        
    # 2.2 full update
    if -1 in last_time or (mnt%10==0 and sec<5):
        print('full update')
        epd.Clear(0xff)        
        epd.delay_ms(100)
        
        YMD(epd, '{:04d}-{:02d}-{:02d} {}'.format(year, mon, day, weekday), wifi_id)
        epd.display(epd.buffer)
        epd.delay_ms(100)
        
        MNIST_clear(epd)
        epd.display_Partial(epd.buffer)
        epd.delay_ms(100)        
        last_time = [-1, -1, -1, -1]
        
    # 2.3 partial update
    for i in range(4):
        if last_time[i] != now_time[i]:
            print('partial update', last_time, now_time)
            last_time[i] = now_time[i]
            
            mnist = get_mnist_font(now_time[i])
            HMS(epd, '{:02d}:{:02d}'.format(hour, mnt))
            MNIST(epd, mnist, i)            
            epd.display_Partial(epd.buffer)
            epd.delay_ms(100)
            
            if i == 1:
                DOT(epd)
                epd.display_Partial(epd.buffer)
                epd.delay_ms(100)
                 
    time.sleep(5)

仓库： https://github.com/shenbo/mnist-clock