围着垃圾堆游费城!!!

2025 年 7 月 4 日是美国法定假日一一独立日。 趁此机会,我休假〇天,前往费城,自助旅游三天。 7 月 4 日出发,7 月 6 日归来,火车往返。 旅游预算一千元,用于支付住宿、交通、景点费用,而且要包括餐饮费用。 特此开帖记录,随时更新。

7 月 1 日起,代表费城 9000 多名市政工人的 DC33 工会宣布罢工。 停摆的业务有:911 调度,图书馆,游泳池,垃圾清运。 其中,911 调度因为涉及公共安全,被法院命令不得罢工。 其余岗位均已罢工,而市长不愿妥协。 据新闻报道,费城的大街小巷已经堆满垃圾袋,苍蝇与老鼠正在狂欢。 可是,我在 7 月 3 日才读到这条新闻,想要打退堂鼓为时已晚,只能继续出行。 这次旅游,恐怕是要绕着垃圾堆走。

7 月 4 日

车票是 6 月 24 日订的。 购票方式是积分+信用卡,这类票可以在开车前全额退票,但是不能改签。 Amtrak 火车票的价格并不固定,而是根据市场需求上下浮动,同样的里程从 10 元到 500 元都有可能。

去程列车从 BWI 站始发,可以选择 09:43 或 10:28 的班次。 我在上次纽约之行得知长途汽车只有 8 点、9 点的班次,而没有 7 点的班次。 8 点的 201 路一般会在 09:20 到达 BWI 火车站,但是过去一年内我已经两次遇到长途汽车机械故障;而且,5 月该车队有一辆车因为刹车故障而引发火灾,车辆被大火烧毁,所幸无人受伤。 所以,我决定订购 10:28 发车的 118 次列车,票价为 47.62 元 + 870 积分。 这样,即便遇上汽车故障,转乘下一班汽车也能赶上火车。

NeoPixels on Fipsy FPGA

Recently I re-discovered that I have a Fipsy FPGA Breakout Board. Back in 2018 when I received this board, I made a version of blinky with five LEDs, lighting up red-green-yellow-blue-white, one at a time. Now, I want to play with something more colorful: NeoPixels!

What is a NeoPixel?

The WS2812 Integrated Light Source, also known as NeoPixel, is a simple, scalable, and affordable full-color LED. Neopixels are commonly found on Adafruit-branded development boards such as the MagTag. They are also available standalone in a zillion form factors. The unit I have is Keyes 18-LED ring WS2812 module that contains a string of 18 WS2812 pixels.

Keyes 18-LED ring WS2812 module

Each WS2812 is a surface-mount package that integrates RGB LEDs alongside a driver chip, forming a complete control of a pixel point. The WS2812 is controlled through a single wire, in which "0" and "1" bits are encoded in the timing of high and low voltage states. During a data refresh cycle, a WS2812 chip accepts 24 bits of data for its green, red, and blue color components, and then forwards any subsequent bits to the next WS2812 chip. This forwarding feature enables cascading: when a string of pixels receives a sequence of 24-bit words, the initial 24 bits go to the first pixel, the next 24 bits go to the second pixel, and so on. Theoritically, you could control a zillion pixels through a single wire.