Raspberry PI Power

[Zbigniew Koziol]

On 02/08/13 20:46, William Weaver wrote:
> Colin,
>
> My bet is that the logitech unifying receiver and the wifi are both 
> requesting a high current usb connection, which is then saturating 
> your 1A power source when the RPis load gets high. Would it be 
> possible for you to measure your current draw from the externally 
> powered power supply?

It is much easier to measure voltage than current. For this one may 
connect voltmeter to two points where the first capacitor is connected, 
just after USB power supplier. I have for instance the following results:

When no any USB is connected, and nothing else, voltage is 5.18 V with 
my USB power supplier.
When I connect USB keyboard only - voltage drops to 5.17
When I connect SSD card only - voltage drops to 5.15 V
With USB keyboard, SSD card and wireless UB mouse - voltage remains 5.15.

These results do not prove much but could indicate on a problem.

Actually, I do have a problem. I would expect that after connecting 
keyboard I should have some response from it (LED lights up/down on 
keyboard after CapsLock is pressed, etc). Unfortunately, I do not see that.

[...]

zb.
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