I can provide a video if it would help. I just got my cube and connected it to Spark.io. When I push demos from cubetube to the cube, everything starts fine. However after 2 seconds, all the leds start flickering like crazy.
I haven't flashed the firmware, but I believe its running the latest firmware photon.
How do I troubleshoot this?
The issue went away after I pushed fireworks.ino to the device. Not sure why it was happening but glad it stopped.
Sounds more like a mechanical problem to me... maybe the J1 side LED strips are loosen? (control signal flows from J1 to J2 and so on until J64 if you look at the markings on the PCB)
It could also be due to a high brightness setting in your code, and your cube being drawing too much current from the power supply. You wanna make sure you're not overdrawing power from the PSU/USB to which your photon is currently plugged in.
I think you might be right here. Using custom colors at lower power 50/255 causes no problems, no matter how often I fill the cube. However, 90/255 causes the 19th stick and on to stop responding (The first 18 * 8 pixels respond as normal in all cases.
Is it external power required to make the cube work properly at full brightness?
I don't feel like this could be a bad connection issue given how reliably all the leds fire under low-brightness circumstances. How could the later leds ever work if there was a mechanical problem?
The maximum brightness you can set with the cube powered by the usb port is around 30~40. With the included power adapter plugged to the photon, that would be around 50~80 (depending on how many LEDs are lit at once - if you're filling the cube all the time, better subtract that number by 10~20).
Included in the baseboard, there's an option for you to connect external power to directly feed the LED strips - if you look at it upside down you will see it labeled as "HIGH POWER". You wire the 5V and GND contacts to an external barrel connector. Then you can plug an external power supply with a capacity of around 10~20A to feed the LED strips while the photon is still fed by the included adapter.
You can read a more detailed discussion (including details on modifying the baseboard) on this subject in this topic.
PS: Quick correction: If you use that external power connector, it'll supply power to the LEDs AND the photon, so you want to make sure there's no power connected to the photon while the external power is used.
Thanks for the info Werner.
So, would it be a problem to try and talk to the photon via usb while its powered externally, or would the photon be smart enough to draw power only from the external source?
Please refer to the Photon's specs - in the Power section, it states that the microUSB power and external power are fed through separate input pins. So if you need to plug your photon to your computer's USB port for some maintenance or setup procedures, electrically speaking it would be wise to disconnect the external power - personally, whenever I need to plug my photon to my PC I remove it from its socket in the baseboard and return it when I'm done working with it while plugged to my computer's USB port.