Benson here again, continuing my reviews of USB Type C legacy cables. Today I am reviewing StarTech's "1m (3ft) USB-C to USB-A Cable M/M - USB 2.0 - USB Type C to USB Type A Cable - USB C to A Cable (USB2AC1M)"
Let's talk about spec compliance. My test setup today include a Chromebook Pixel 2015, and a Chromium OS USB-PD Sniffer (codename Twinkie). Please check it out by searching google for "Chromium USB-PD Sniffer". This product is also available on Amazon here : Plugable USB 3.1 Type-C (USB-C) Power Delivery Sniffer
I got a comment in one of my previous reviews that I should be testing with a 2.4A capable power supply to demonstrate that the cable is of good enough quality to sustain 2.4A charging, so for this review, I am using one of Apple's 1st party power adapters with a 5.2V, 2.4A charging capability, specifically Apple's 12W iPad charger.
Running the ectool command on Pixel: localhost ~ # ectool --dev 1 usbpdpower Port 0: SNK Charger Proprietary 4618mV / 2400mA, max 5000mV / 2400mA / 12000mW Port 1: SRC
In this case, the Pixel has negotiated up to 2.4A of charging through the StarTech cable to the Apple charger.
Switching over to the USB PD sniffer, I'll run the "tw cc" command to get a voltage reading on both CC lines: > tw cc CC1 = 417 mV ; CC2 = 20 mV
The important number to look at here is CC1, which indicates a voltage of 417mV. If you refer to the USB Type-C Specification 1.1 Table 4-25. Look at the row labeled vRd-USB, which indicates the legal voltage values to read from the CC pin in order to be categorized as "Default USB Power". The range is Min : 0.25V Max : 0.61V. For this cable, I measured a value of 0.417V right in the middle of this range, indicating that yes, this cable has a 56k' resistor and is within spec for CC termination.
One more twinky command : > tw vbus VBUS = 4702 mV ; -2451 mA
The vbus command here uses twinkie's built in current and voltage meter. It's confirmed that Pixel is charging at 2.4A.
For a USB 2.0 High Speed data test, I’ve hooked my Nexus 5X to my Chromebook Pixel via the StarTech Type-A to Type-C cable to test large file transfer via MTP. It just works, no problem!
For other more subjective judgements of this cable : The Type-C plug on this cable is the stamped variety, meaning it has a seam on one side of the cable. This is ok, but not as great as the deep-draw plugs we see on other cables (especially 1st party ones from Google and Apple). The cable has a black plastic tip. What's really nice about StarTech cable is that the length of the cable is super thin and flexible PVC. Despite being so thin and light and flexible, the cable is designed well enough to handle 2.4A charging.
In conclusion, this is a fine cable for your Nexus 6P/5X to use with all of your older USB Type-A chargers, hubs, and PCs. It also works great with Chromebook Pixel 2015 and will work great on USB Type-C spec compliant devices to come!