type-c

USB Type-C 要增加 240W 的規格...

在「USB Type-C Specification 2.1 allows up to 240W Extended Power Range (EPR)」這邊看到這個規格：

Extended Power Range cables have additional requirements to assure that these cables can deliver the full defined voltage and current range for USB PD EPR operation. EPR cables shall functionally support a reported 50 V and 5 A o peration. The minimum functional voltage that a cable shall support is 53.65 V. The electrical components potentially in the path of V BUS in an EPR cable, e.g. bypass capacitors, should be minimally rated for 63 V.

All EPR cables shall be Electronically Marked and include EPR-specific information in the eMarker as defined by the USB PD specification. As defined in the USB PD specification, EPR cables are marked as 50 V and 5 A capable. All EPR cables shall be visibly identified with EPR cable identification icons as defined by the USB-IF. This is required so that end users will be able to confirm visually that the cable supports up to as high of PDP = 240W as defined in the USB PD specification.

也是基於 E-Marker 晶片的關係，除了充電頭支援外，線本身也得支援。這解決了目前很多家桌機都自己搞 >100W 的 dock 來支援高瓦數的充電，推出一個標準來涵蓋收斂...

會不會搞到以後連桌機都可以用 USB-C 界面供電啊...

老闆走近時自動切換視窗的玩具...

看到「Daytripper: Hide-My-Windows Laser Tripwire」這個東西，可以偵測有人走過 (然後你就可以設定後續的行為)：

用電池供電，充滿可以供應 40 小時，然後再用 Type-C 充電...

Raspberry Pi 4 的 Type C 無法使用 Macbook Charger 供電的問題

Raspberry Pi 4 出來後有些災情 (畢竟又加了不少東西近去)，在 Hacker News 上看到的 Type C 介面的充電問題：「Raspberry Pi 4 not working with some chargers (scorpia.co.uk)」，引用的原文可以在「Pi4 not working with some chargers (or why you need two cc resistors)」這邊看到，裡面提到了新的 Type C 供電介面在接某些充電器時不會供電 (包括了 Macbook 的充電器)：

The new pi has been released and it has a USB Type-C connector for power however people are finding some chargers are not working with it (notably macbook chargers). Some have speculated that this is due to a manufacturer limitation on the power supplies however it is actually due to the incorrect detection circuitry on the Pi end of the USB connection.

這樣說有點偏頗，但是 Macbook 的充電器一向是 Type C 裡的指標，如果這顆充電器跟其他裝置配合上有問題，通常都是代表其他裝置的實作有問題... (噗)

這次發現的電阻問題看起來有點苦 (看起來需要改版子)，目前文章作者建議的 workaround 主要就是「不要用那麼好的設備」，比較簡單的包括了 Type C 的線不要那麼好 (像是找充手機用的線就好，不要找拿可以跑 5A 的線)，或是透過 Type A 轉 Type C 的線也應該可以避開這個問題，最差的情況應該是找其他的充電器：

Now onto some solutions. Assuming the issue you are having is caused by the problem discussed above, using a non e-marked cable (most USB-C phone charger cables are likely this type) rather than an e-marked cable (many laptop charger/thunderbolt cables and any 5A capable cable will be in this category) will allow for the pi to be powered. In addition using older chargers with A-C cables or micro B to C adaptors will also work if they provide enough power as these don’t require CC detection to provide power. Ultimately though the best solution in the long run will be for there to be a board revision for the pi 4 which adds the 2nd CC resistor and fixes the problem.

對於已經入手的人，如果真的中獎，workaround cost 應該還在可以控制的範圍...

Raspberry Pi 4 開賣，USD$35

Raspberry Pi 4 開賣，目前推出的是 Model B，最低規格的 1GB RAM 版本與之前 RPi 3 相同都是 USD$35，另外這次提供了以前沒有的 2GB 與 4GB 版本，分別是 USD$45 與 USD$55：「Raspberry Pi 4 on sale now from $35」。

有兩個比較大而且要注意的改變，第一個是電源接頭變成 Type-C 了：

We’ve moved from USB micro-B to USB-C for our power connector. This supports an extra 500mA of current, ensuring we have a full 1.2A for downstream USB devices, even under heavy CPU load.

另外一個是 HDMI 接頭換成 D Type：

To accommodate dual display output within the existing board footprint, we’ve replaced the type-A (full-size) HDMI connector with a pair of type-D (micro) HDMI connectors.

這兩個改變都需要準備額外的設備或是線材，其他的改變應該還好...

這次改版最明顯的是效能的增加，官方宣稱 CPU 速度是前一代的三倍：

A 1.5GHz quad-core 64-bit ARM Cortex-A72 CPU (~3× performance)

而在 GPU 相關的則是對 H.265 的 4Kp60 硬體解壓縮：

4Kp60 hardware decode of HEVC video

先前用 RPi 3 放客廳還是覺得不太夠，也許可以考慮看看這個...