A20-OLinuXino-LIME-4GB doesn't work

[pomkalk]

I have some problem with my olinuxino. When I try to power it, nothing happens, only Ethernet LEDs flashes one time.
I used hdmi cable connected to TV, usb-otg cable and power charger of LENOVO (5V DC/1A).

[pomkalk]

So, Will it work: Lenovo charger(like at image below)+usb-otg cable+A20-OLinuXino-LIME-4GB? And +hdmi+TV

[JohnS]

Common problems are:
1. power supply (not enough current, bad volts, noise, etc)
2. not waiting long enough, especially on first power up
3. using the wrong output device (one that is not what the software is driving, wrong resolution, etc)
4. using the wrong uSD card image or writing the card in the wrong way
5. I forget - but users are very creative at making things not work...

#1 is very common as you can see from posts all over the forum

#2 can lead to corruption of the NAND image, I understand

John

[lucalorenzon]

I've the same problem. I received the board two days ago, I've powered it through the mini usb port (usb-otg) as described on the user manual, but nothing happened. The hdmi doesn't receive any signal. I've been waiting for more than 5 minutes, is it enough?

[jmyreen]

What I would try next would be to connect a suitable power supply to the barrel connector instead of the USB OTG connector. The connector makes a difference: power from the USB connector goes via U13, which is an AXP209 power management unit IC.

From the A20-OLinuXino-LIME user's manual:

"The best practice is to never count on the mini USB-OTG as a single source of power for the board!
The preferred way of powering the board is via the PWR jack with 5V DC. This would make the
board fully powered and able to power all the peripherals connected to it."

[obcd]

Same issue here with a LIME 2
Powering trough the barrel connector with a 5V 2Amp supply from a powered usb hub solved the issue.
I can understand they don't want you to rely on the USB OTG to power the device, as a USB HOST port (which is what you could use with an USB to micro usb cable) is normally limited to 500mA. If you use an adapter however, it can be 1A up to 2A, so that shouldn't be the problem.

Isn't there a signal line in the OTG telling if it's a device or a host? Maybe a power adapter isn't setting that correctly. (Just a wild guess.)

[jmyreen]

A USB device playing by the rules is required to initially draw only one "unit of power", which equals 100 mA (150 mA on USB3). After booting up, it may negotiate with the host, requesting up to five units (500 mA; six units on USB3 = 900 mA).

The Olinuxino boards have a very complex, programmable power management integrated circuit (AXP209), which by default limits the current drawn from the USB bus to 900 mA. The limit can be adjusted by writing to a register in the IC; the alternatives are: 100 mA, 500 mA, 900 mA and no limit. If the system draws more current than it is allowed to, the APX209 shuts down the system.

No such limit is imposed on the power from the barrel connector, which makes it a safer bet to use it instead of the USB OTG connector.

Edit: Unfortunately, the APX209 on the Lime2 is not programmable because the I2C interface is not connected to the CPU.