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gkaindl / ambi-tv

a flexible ambilight clone for embedded linux
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questions reg power supply #35

Open vkastala opened 10 years ago

vkastala commented 10 years ago

Hi, Thanks for everyone for putting up such a great project. I am kind off new to this type of projects so my questions might be a bit too naive. I ordered the parts and waiting for them to come by this week. I do have a couple of questions:

1) Regarding using two power supplies: Can I power the RPi using the regular Micro USB power port and power the RGB strip using a differnt 5V power supply? In one of the previous posts i did read that we need to connect the ground pins if two independent power supplies are used. If two power sources are used (where the rpi is powered by micro-usb power port) can we just connect the ground of RGB strip to GND of RPi GPIO pin?

2) I am keeping my fingers crossed as to which chipset my USB grabber will have. Based on the comments so far can you tell me if these are the supported devices: a) If the chipset says STK1160 (from lsusb) then it is supposed to work as is. b) If the chipset says Fushicai USBTV007 we should be able to get to working as if we follow the steps mentioned in this projects wiki.

Thanks in advance for your help.

Regards, Venkat

samick99 commented 10 years ago

1) That would work; just verify the GPIO pin that is supposed to be gnd is shorted to chassis ground which is the micro USB casing. 2)b) I have no idea.

vkastala commented 10 years ago

Thanks Samick for the reply. If possible can you explain a little bit more on what you meant (by chassis ground)?

samick99 commented 10 years ago

You could google it :) But basically it's the reference (ground or 0 volts) for the rest of the voltages in the system. That's why you want to connect the grounds of all power supplies together with the grounds of any other electronics in the circuit (the LEDs and Pi). It assures everything is using the same reference for 0 volts so you don't have a "floating" ground or voltage out there. The micro USB housing is definitely connected to "chassis" ground of the Pi. If you take a voltmeter and check continuity between the ground pin on GPIO port and USB housing and find that they are shorted, then you're good to go with using the GPIO pin for your ground reference!

vkastala commented 10 years ago

thanks samick again. I was reading through some articles and someone pasted the schematics and says that the grounds are connected. http://raspberrypi.stackexchange.com/questions/3769/ground-of-gpio-and-micro-usb

I did recieve my USB grabber but it has Empia chipset on it so I guess I will have to reoder one more to get the fushcai or stk chipset USB grabber.

samick99 commented 10 years ago

I have ordered 2 of these and it was the correct chipset both times:

http://www.amazon.com/gp/product/B00AH99L5O/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

vkastala commented 10 years ago

Ordered the one you mentioned in previous post. Yet to get the USB grabber and RGB led strip. Playing around with soldering as it is first time. Will update once i make some progress. thanks samick.