Actual voltages, amperage

[NexusDude]

This is not a complaint, but just FYI for anyone who wants to know. I've had zero issues with the Pine's USB ports.

According to my USB meter, I've seen the voltages of the USB 2 ports vary between 4.77 - 4.94V. Typically, 4.89 - 4.92V.

The amperage is 0.07 - 0.08A for the flash drives I've tested. 
For keyboard, mouse, or powered hard drive, it's 0.00A.
I don't have a working wifi dongle, yet...

[pfeerick]

Great to see some more real-world data being collected!

I decided to be nasty to mine, and plug in a 1TB external hardrive that is USB powered. When doing something like a 

Code:

find /media/usbhdd -mindepth 2 -type f

across it, to make sure it was being kept busy, I got surges of up to 500ma on the USB port, and a voltage sag of down to around v4.69 (and I'm wondering if the PMA chip is actually clamping down there as I've seen mention of that on another board with the same chip). When the drive is spinning but not active, with a load of about 220ma, I get a more reasonable v4.97. When the hdd shut down, it presented a 149ma load, and the voltage was 5.02v. 
This is with an input voltage of 5.25v (and up to 5A available) into the pine64 via the microUSB, with the USB ports reporting 5.14v with nothing plugged into them (except the meter). A keyboard/mouse receiver presented as a mere 21ma load, and the voltage stayed at 5.12v. 
Pete

[MarkHaysHarris777]

I swapped out the 2A PSU with a good 2.5A switching PSU with good two wire cord and the 5v supply is running 5v02 with usb receiver, 5v fan, and LED lab. Several of my PSUs claim to be 5v @2.4 A but really are not... either because they're switching characteristics are not up to par or their power cord is too thin... rats.

The international version of the Raspberry PI switching PSU seems to be worth the bucks.

[pfeerick]

I swapped out the 2A PSU with a good 2.5A switching PSU with good two wire cord and the 5v supply is running 5v02 with usb receiver, 5v fan, and LED lab.  Several of my PSUs claim to be 5v @2.4 A but really are not... either because they're switching characteristics are not up to par or their power cord is too thin...  rats.

The international version of the Raspberry PI switching PSU seems to be worth the bucks.

I'm using a so-called "DC 9V-35V to 3-6V Adjustable 4-USB Step-down Power Supply Converter Board Module" from eBay - has four USB outlets, plus a screw terminal output, and you can fine-tune the output to your needs. I found this unit perfect for my needs as a lot of my electronics stuff is running from a 12v solar charged setup, so needs to be 11v - 15v powered!

The adafruit stuff is great, especially their 5v power supplies, as they also fine-tune the output voltages so they are slightly high, to try and overcome poor wiring and voltage sag on longer runs.

[NexusDude]

The original post is about the USB2 ports and their output. 

[MarkHaysHarris777]

The original post is about the USB2 ports and their output. 

The 5v rail is consistent throughout the board.  I have taken measurements all over the board; including the 5v pin on the RPi port. There shouldn't be one speck of difference.

[pfeerick]

The original post is about the USB2 ports and their output. 

Oops! Well, we were still talking about USB, so maybe only slightly off topic there?   Point taken though... it is more about the output limitations, rather than the input devices! Especially how the AXP803 reacts to loads on the USB. On another board I have, it clamps the output to 500ma, and from the clicking sounds I would occasionally hear when the usb HDD was plugged in and running the file scan, I suspect this chip is configured to have the same limits. Hopefully we can access the AXP803 chip over the i2c like the other board, and configure parameters such as this...

[g_t_j]

The international version of the Raspberry PI switching PSU seems to be worth the bucks.

Can you please link the exact PSU you are referring to?

[MarkHaysHarris777]

http://www.gigaparts.com/Product-Lines/P...aQod-qEAmQ

http://www.mcmelectronics.com/product/28-21442


You can find them other places too, at varying prices and availability. I got mine from MCM.

(second link above)

[g_t_j]

http://www.gigaparts.com/Product-Lines/P...aQod-qEAmQ

http://www.mcmelectronics.com/product/28-21442


You can find them other places too, at varying prices and availability.  I got mine from MCM.

(second link above)

Thanks a bunch!