蓝牙buffer 20字节分包

subpackageSend(buffer) {
    let length = buffer.byteLength;
    let count = Math.ceil(length / 20); //最多执行 count 次
    for (let i = 0; i < count; i++) {
        console.log("进行第" + i + '次数据写入');
        let TempBuffer;
        if (((i + 1) * 20) < length) {
            TempBuffer = buffer.slice(i * 20, (i + 1) * 20);
        } else {
            TempBuffer = buffer.slice(i * 20, length);
        }
        setTimeout(() => {
            this.send(TempBuffer);
        }, 250 * i) //250秒延迟，防止错乱
    }
},