0

I've been looking through the specs of my 2014 MacBook Air in order to resolve a certain issue.

The hub speed cought my attention:

BRCM20702 Hub:

  Product ID:   0x4500
  Vendor ID:    0x0a5c  (Broadcom Corp.)
  Version:  1.00
  Speed:    Up to 12 Mb/sec
  Manufacturer: Apple Inc.
  Location ID:  0x14300000 / 4
  Current Available (mA):   500
  Current Required (mA):    94
  Extra Operating Current (mA): 0
  Built-In: Yes

The speed is 12 megabits per second, right?

How do I get a USB disk data transfer speed of about 10 megabytes per second? To make it funnier, the peak speed is about 50M, but that is just buffering. The actual average long-term large-volume speed is about 10M.

Also, the hub speed is a USB 1.X speed, while the body features USB 3 ports. What's the catch?


Edit:

Here's the data for the dock connected over a USB 2 cable:

JMS56x Series:

  Product ID:   0x9561
  Vendor ID:    0x152d  (JMicron Technology Corp.)
  Version:  1.05
  Serial Number:    00000000000000000000
  Speed:    Up to 480 Mb/sec
  Manufacturer: JMicron
  Location ID:  0x14200000 / 22
  Current Available (mA):   500
  Current Required (mA):    2
  Extra Operating Current (mA): 0

The dock is under the USB 3.0 bus (no speed specified):

USB 3.0 Bus:

  Host Controller Driver:   AppleUSBXHCILPT
  PCI Device ID:    0x9c31 
  PCI Revision ID:  0x0004 
  PCI Vendor ID:    0x8086 

The slowest disk is 5400 RPM Toshiba HDWL120. It's transfer speed is "non-public" (weird). It should be much higher than 10 MB/s though.

3
  • Yes, your acutal transfer speed is max 12mbit/s. Whats the exact product (hub) you are using? what cables are you using? what drive (HDD) are you accessing. All these parts are potential bottlenecks, without knowing what exactly is your hardware setup its impossible to answer.
    – X_841
    Jan 4, 2022 at 19:44
  • Isn't the BRCM20702 a USB Bluetooth adapter?
    – Gilby
    Jan 4, 2022 at 22:18
  • I've seen the bluetooth adapter as a separate device. This thingy here says "hub". Although, yeah, under it there is the bluetooth device. Jan 6, 2022 at 13:56

1 Answer 1

1

The BRCM20702 is the Broadcom USB hub for the Bluetooth controller. So it only needs 12 mb/s speed.

It has little to do with the external USB 3 ports except that it uses USB protocols to communicate with the CPU.

Connect a disk drive and using System Information inspect the USB section. You will see there that you have USB controller and hub used for the USB 3 ports running at 5 Gb/s.

4

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .