AXP209 - how to test?

JohnS · January 22, 2013, 10:31:22 PM

I went back through my log files of (trying to) boot Linux on my A13 WiFi and found that whenever it failed to boot the AXP did not initialise (and failed even to report the chip ID).

How do I test for a faulty chip?

Hardware and software suggestions, please.

It was apparently OK only when a LiPo battery was connected.

Or am i seeing "expected" behaviour?

John

JohnS · January 24, 2013, 12:21:02 AM

bump

Anyone?

jwischka · January 24, 2013, 12:31:46 AM

I got nothing for you... sorry.

JohnS · January 24, 2013, 01:50:42 AM

Thanks.

OLIMEX - anyone?

The chip does not respond on the i2c bus and never did except when the LiPo was connected and working.

JohnS · January 24, 2013, 04:45:12 PM

hmm, just about a one-person thread LOL

I have more data.

My AXP209 does start sometimes. It either works or doesn't and this affects both Android and Linux (as you'd hope).

When it fails I get BogoMIPS 383.38 and when it works 1001.88
Also, when it fails Android's Linux kernel crashes with a NULL pointer deref just the way (non-Android) Linux does.

I can get it to work using the same PSU if I take it to another part of my building. So it's noise either from the mains or RFI / EMI.

I'm surprised if it's either as the board should reject them!

olimex · January 24, 2013, 05:21:31 PM

there is easy way to see if AXP209 works or not, when it starts it have some default safe voltages on the DCDC but I do not remember exact values - should be around 1.1-1.2V then with the I2C commands you can set them up/down and this is what usually kernel does to have 1008Mhz clock the core voltage should go up to 1.4V IIRC
in your case AXP works as otherwise your board would have no power supply but the I2C communication is lost from time to time for some reason - look if there is no broken trace or component around the I2C path

JohnS · January 24, 2013, 07:03:11 PM

When it's failing it does not respond on the I2C bus - even repeated use of i2detect / i2cdump cannot see it.

I'd love it to be a solder or similar problem but it seems consistent about where in the building it works and where it fails. I will check more over the next days.

I have no special devices to test for RFI / EMI or for any strange noise spikes etc on the mains

I might try it in a metal case, though the WiFi will be awkward...

steveh · February 16, 2013, 01:50:43 PM

Hi John,

It seems one of my boards has exactly the same problem. On power up with a fully powered AXP209(ACIN and VBUS), I get a dormant AXP209 (no IPS, no outputs at all - just a 2.5v Internal Vref). Cycling the power several times has the AXP209 working now and then and it powers up its outputs. When it does work, it works well. All rails rock solid and stable. When it dosent, all I get is vref of 2.5.

Pressing the on switch shows a small blip of about .5v on IPS out, and then it goes off again. Very annoying, especially when the AXP209 manual is a mess.

How did you go with your problem? Did you find anything?

Im about to start debugging this one.

Steve

Quote from: JohnS on January 22, 2013, 10:31:22 PM
I went back through my log files of (trying to) boot Linux on my A13 WiFi and found that whenever it failed to boot the AXP did not initialise (and failed even to report the chip ID).

How do I test for a faulty chip?

Hardware and software suggestions, please.

It was apparently OK only when a LiPo battery was connected.

Or am i seeing "expected" behaviour?

John

JohnS · February 16, 2013, 03:06:26 PM

It just started working most (all?) of the time.

When not working it didn't respond to i2c (such as commands from uboot). Voltages looked plausible but it of course did not output the higher voltage to run the CPU at proper speed (because i2c commands are sent to tell it to do that).

If you decide to try playing with uboot it's easy to build and the sunxi wiki etc explains plenty (just google for it) together with the uboot manual.

Good luck!

John

vijayboboe · May 17, 2014, 09:32:05 AM

We designed based on Allwinner A20 processor with AXP209. Now we are facing a problem related to power. We are using only ACin for powering.

When we power on with 5V to ACIN, we are getting 3V,1.3V, 2.8V, 1.2V & other voltages only for 100ms. After that all the voltages goes down to 0V except 1.3V LDO and we are getting VINT as 2.5 V and 1.2V on Bias pin.

Pressing the N_OE switch shows a small blip for same 100ms. We have done prototype for 5 boards, all the boards are behaving same.

dave-at-axon · May 17, 2014, 05:04:38 PM

Is there anything else on the I2C bus that is not powered up?

I've seen this with my current prototype board where power was removed and this caused issues on I2C-0 and the processor was not able to communicate with the AXP209.

Check your I2C bus is working.

vijayboboe · May 23, 2014, 10:49:28 AM

Hi,
Thank you for your response.

The I2C from the AXP to A20 is one to one. I2C lines got the 2K2 Pull ups which is properly tied with 3V3. And the connectivity is also there. There is no short between the lines and between lines & ground.

When I probe the I2C lines, It ramps up to 3v3 for 100 ms and then goes down. Because 3V3 IC is enabled by the AXP EXTEN pin. Since AXP is shutting down, I2C pull up is also going to Zero.

Then I removed the EXTEN pin from 3V3 IC and 1V5 IC Enable pin and I tied directly with 5V in. Now I am getting constant 3V3 and 1V5 DDR but, We are not getting 1V2 INT, 1V2 CPU, 3V0AVCC, 2V8 Continuously. Only 1V3 is Continuously. Every thing shoots up to right voltage and then shutting down to 0V after 100 ms.

We have no idea why it is happening. Do you have any suggestion ?

With Regards,
Vijay

dmsherazi · January 26, 2016, 07:26:36 AM

Hi vijayBoboe...

Did you happen to solve the issue? I am having exactly the same problems and am stuck...

Quote from: vijayboboe on May 23, 2014, 10:49:28 AM
Hi,
Thank you for your response.

The I2C from the AXP to A20 is one to one. I2C lines got the 2K2 Pull ups which is properly tied with 3V3. And the connectivity is also there. There is no short between the lines and between lines & ground.

When I probe the I2C lines, It ramps up to 3v3 for 100 ms and then goes down. Because 3V3 IC is enabled by the AXP EXTEN pin. Since AXP is shutting down, I2C pull up is also going to Zero.

Then I removed the EXTEN pin from 3V3 IC and 1V5 IC Enable pin and I tied directly with 5V in. Now I am getting constant 3V3 and 1V5 DDR but, We are not getting 1V2 INT, 1V2 CPU, 3V0AVCC, 2V8 Continuously. Only 1V3 is Continuously. Every thing shoots up to right voltage and then shutting down to 0V after 100 ms.

We have no idea why it is happening. Do you have any suggestion ?

With Regards,
Vijay