Paperang(喵喵机) Python API, now with Little Printer integration!

Requirements & Dependencies

OS: OSX (tested on Catalina)/Linux (tested Debian Buster on a Raspberry Pi 4)
Python: 3.5-3.7 (tested)

Required debian packages: libbluetooth-dev libhidapi-dev libatlas-base-dev python3-llvmlite python3-numba python-llvmlite llvm-dev

Python Modules: install with pip3 install -r requirements.txt

macOS instructions

Set up and test your printer

You'll need python3 installed; check if you have it by typing which python3 in Terminal or your favorite console application.

1. Install necessary python modules:

pip3 install -r requirements.txt

2. Ensure bluetooth is enabled on your computer. You do not need to connect your Paperang to your computer yet! We'll do that later, via the command line.
3. Turn on your Paperang and set it near your computer
4. Run the test script, which will tell your Paperang to print a self-test if it's successful:

python3 testprint.py

If you've never paired your Paperang with your computer, you might get a dialog asking you to allow the Paperang to pair with your system. Click connect. You should only have to do this once.

5. If the test print was successful, the script will print out your device's MAC address on the console, as well as on the printer. You can enter that into the script to connect to your Paperang directly, avoiding the wait time for scanning for printers.

If you need to look up your Paperang's MAC address quickly, you can use the system_profiler command to output information on all paired bluetooth devices:

system_profiler SPBluetoothDataType

Enable the HTTP Server API

Now, you can start an http server for use the printer via POST API using HTTP protocol. Before, verify that the requirements and debian packages are installed (if you are running on debian distro). Install the requirements. Break this step if you have installed the requirements in above sections.

pip3 install -r requirements.txt

Copy and configure your config.py file and replace the variables maccaddress, hostname, port with your papreang printer's mac address, your hostname to bind (0.0.0.0 default) and your desired port (8888 default). If you don't know what is your maccaddress it's very easy to get: put paper in the printer, press the power button one time for 3 sec. for turn on the printer, after the green led is on make a double-press to the power button, then the printer will print a QR code. Scan the QR and you'll get an URL address. Check the last parameter named deviceId=macaddress and get your macaddress.

cp config.example.py config.py
nano config.py

Finally, The file looks like that:

#!/usr/bin/env python3
macaddress = "FF:FF:FF:FF:FF:FF" # REPLACE WITH YOUR MACADDRESS
width = 384
hostname = "0.0.0.0"
port = 8888

Run the server:

python3 http_server.py

The script will output the next if everything it`s right:

Trying to connect to printer with MAC address "FF:FF:FF:FF:FF:FF"
Serving static files from /home/username/python-paperang2/public
Listening on port 8888

Now it's alive. You can open your browser and navigate to http://localhost:8888/ and select a image file to send to printer API. Here is the CURL command for make your requests. The API accpets .png and .jpg files.

curl 'http://localhost:8888/api/print' \
  -H 'Content-Type: application/octet-stream' \
  --data-binary "@/path/to/your/image.jpg"

And the javascript function to send Image to print:

/**
 * Send a image file to the API
 *
 * @param {File} file - The image file to send.
 */
function sendToAPI(file){
    fetch('http://localhost:8888/api/print', {
        method: 'POST',
        headers: {
            'Content-Type': 'application/octet-stream',
        },
        body: file,
    }).then( response => {
        console.log("Send image to printer:",response.statusText)
    })
    .catch( err=> { console.log(err) } )
}

Ussage:

const onInputFile = (event) => {
    const file = event.target.files[0];
    if (file) {
        sendToAPI(file);
    }
};

Print Little Printer data

Establishing a connection

BtManager() Leave the parameters blank to search for nearby paperang devices

BtManager("AA:BB:CC:DD:EE:FF") Calling with a specific MAC address skips searching for devices, saving time

Printing images

The printer's API only accepts binary images for printing, so we need to convert text to images on the client side.

The format of the printed image is binary data, each bit represents black (1) or white (0), and 384 dots per line.

mmj = BtManager()
mmj.sendImageToBt(img)
mmj.disconnect()

其他杂项

registerCrcKeyToBt(key=123456) 更改通信CRC32 KEY(不太懂这么做是为了啥,讲道理监听到这个包就能拿到key的)

sendPaperTypeToBt(paperType=0) 更改纸张类型(疯狂卖纸呢)

sendPowerOffTimeToBt(poweroff_time=0) 更改自动关机时间

sendSelfTestToBt() 打印自检页面

sendDensityToBt(density) 设置打印密度

sendFeedLineToBt(length) 控制打印完后的padding

queryBatteryStatus() 查询剩余电量

queryDensity() 查询打印密度

sendFeedToHeadLineToBt(length) 不太懂和 sendFeedLineToBt 有什么区别，但是看起来都是在打印后调用的。

queryPowerOffTime() 查询自动关机时间

querySNFromBt() 查询设备SN

其实还有挺多操作的，有兴趣的看着const.py猜一猜好了。

图像工具

ImageConverter.image2bmp(path) 任意图像到可供打印的二进制数据转换

TextConverter.text2bmp(text) 指定文字到可供打印的二进制数据转换

微信公众平台工具

两个小脚本，用来实现发送图片给微信公众号后自动打印。

wechat.php 用于VPS接收腾讯数据，默认只允许指定用户打印。

printer_server.py 放置于树莓派等有蓝牙的靠近喵喵机的机器上运行，可以使用tinc等建立VPN以供VPS直接访问。

吐槽

这玩意就不能增加一个多次打印的功能吗？以较低温度多次打印再走纸，应该可以实现打印灰度图的。

逆了好久的固件也没搞出来啥东西，真是菜。希望有大佬能告诉我一点人生的经验。

顺便丢两个芯片型号: NUC123LD4BN0, STM32F071CBU6，似乎是Cortex-M0。

PS: 本代码仅供非盈利用途，如用于商业用途请另请高明。

Acknowledgement 致谢

Thanks for all the reverse engineering work done by the original author of this project.