Did I brick my Axon?

[E.Mk]

Hey all,

I was playing around with the Axon + Serial Graphic LCD 128x64(http://www.sparkfun.com/products/9351) + 5V battery pack(4 AA batteries + 5V voltage regulator).  I was uploading test code in Ubuntu VirtualBox VM in a Mac.  Suddenly I can't seem to download the Axon.hex to the device - the bootloader just spins in place, displaying Waiting for Device.

Here are the steps I followed;

• plugged in the USB cable on my Mac
• Started VirtualBox
• Started Ubuntu VM
• Added Silicon Labs CP2102 USB to UART Bridge Controller to the Ubuntu VM
• set baud rate on ttyUSB0 to 115200 via stty -F /dev/ttyUSB0 115200
• executed the linux bootloader to transfer Axon.hex via bootloader -d /dev/ttyUSB0 -p Axon.hex
• powered up the Axon

now this worked but now the bootloader can't detect the Axon powering up.

What I did notice is that if I unplug the USB cable, ttyUSB0 device goes away and the USB devices tab under the VM menu shows that the SiLabs CP2102 is no longer connected.

Does this mean I've bricked the device and need to follow the instructions found in the FAQ?  I'm a beginner and I'm not sure what happened?  The Axon lights up and the battery pack seems to be fine when I connect it to a multimeter.

Thanks in advance!

[Admin]

5V battery pack(4 AA batteries + 5V voltage regulator)

What battery type are you using? I almost suspect the issue is the voltage is now too low for your Axon to turn on properly. Check with a multi-meter.

The CP2102 gets power from your computer, so it'll work whether the ATmega640 is working or not.

That said, how is your Sparkfun LCD working for you? I ask because the SF 20x4 LCD is complete garbage.

[Soeren]

Hi,

And adding to that, what voltage regulator?

Alkaline primary cells (non rechargeables) start out at around 1.65V when spanking new, but falls quickly to 1.5V - they are considered flat at 0.9V
A 4 cell battery thus have a range of 6.6V down to 3.6V over its useful life.

Voltage regulators have a voltage drop (needs some voltage to work) that can be up to 3.5V for "normal" regulators and down to a few tens of mV for Low Drop Out (LDO) types.

The easy, albeit lossy, solution is to add a couple of cells to the battery, getting the range up to 9.9V to 5.4V and making sure an LDO regulator having less than 0.4V drop out voltage (or accept a bit higher drop out, when the cells go below 1V on moderate current draws, most of the juice is gone anyway).

[Admin]

Well, my assumption was he is using the LDO regulator on the Axon, meaning he needs no less than 5.3V (6V recommended). Meaning if his cells drop to even 1.3V each (5.2V total), the Axon will have a power failure.

[E.Mk]

Hey guys,

First off, happy thanksgiving to practicing Americans

To answer several questions -
Battery Pack

• 4 AA Alkaline batteries
• 1 5V regulator from RadioShack
• Multi-meter reports about 4.5V

NOTE : this battery pack worked sufficiently well in the past when I was downloading code onto the Axon, plus after it wouldn't recognize, I tried changing the batteries to new ones to no effect.  TL;DR - the battery pack as is has worked before many times and upon the Axon not working, tried new batteries

Serial Graphic LCD 128x64(http://www.sparkfun.com/products/9351)

• Haven't had chance to get it work successfully - still mucking around

NOTE : I've tried connecting the Rx from LCD to UART0-T on the Axon, G to UART-0-G, and the Vin to E2+(middle) for the power.  When the Axon is powered up, the LCD lights up, but I haven't been able to get it to enter into the Demo state (from SparkFun, I have to send it 0x7C and 0x04 via

         rprintf("Starting LCD Demo\r\n");

         uart0SendByte(0x7C);

         uart0SendByte(0x04);

in the control.c file.  I also set UART0 to 115200 baud as per instructions in the Axon.c file by changing line

    uartSetBaudRate(0, 38400); // set UARTE speed, for Bluetooth

to


    uartSetBaudRate(0, 115200); // set UARTE speed, for Bluetooth


in the main function.

Any and all help would be greatly appreciated.

Thanks in advance!

[Admin]

Your issue is the power supply. Remove the radio shack 5V regulator, and plug your batteries directly into BAT of the Axon.

The Axon won't work properly unless you power it with at least 5.3V at BAT.

As for your LCD display, read this post in it's full entirety:
http://www.societyofrobots.com/robotforum/index.php?topic=12221.0

[E.Mk]

Your issue is the power supply. Remove the radio shack 5V regulator, and plug your batteries directly into BAT of the Axon.

The Axon won't work properly unless you power it with at least 5.3V at BAT.

As for your LCD display, read this post in it's full entirety:
http://www.societyofrobots.com/robotforum/index.php?topic=12221.0

You are absolutely correct!  I found a Regulated AC-DC Adapter and set that to 6V and connected that to the Axon and that worked!

Thanks to Admin and Soeren for their insight and help!

Admin;
The LCD from SF seems to work (got as far as start off the Demo by sending 0x7C 0x04) so far - haven't really gotten too far into using it.