Internal Voltages

[EdCa22]

I have been planning to place some circuits inside the pandora, and am currently in the process of designing PCBs for them... however it would be extremely useful to have some information on what voltages are available inside the pandora (from test points/other pads) and how much spare current can be drawn from each - if you would be so kind! Specifically I need to use 3.3V, 1.8V and 5V, and need to figure out if these are already present or if I have to include regulators or buck-boost converters, and also if they are present whether they provide enough current for my application.

Thanks!

Also, while I'm here, are there any spare pins on the EXT connector that I can use to route signals to the outside world without making holes in the case? And can we have the LCD cable pin out and connector part no, if not now then at some later point?

 

[Kimundi]

Well, I can assure you that there are no spare pins on the ex connetor:
14 pins:
4 Audio (L/R In/Out)
2 Video out (S-Video)
2 Serial 1 (TX/RX)
4 Serial 2 (TX/RX/RTS/CTS)
1 Power (max 2.8V 200 mA)
1 GND

 

[Squidge]

Probably easiest to suck the 5V from the USB host connector and regulate it yourself rather than guessing the current handling capabilities of various points on the board.

 

[trats20050]

May we ask what kind of circuits .

 

[EdCa22]

Probably easiest to suck the 5V from the USB host connector and regulate it yourself rather than guessing the current handling capabilities of various points on the board.

Yeah, but then I can't guarantee 500mA from the USB connector... I don't want to cripple one feature to add another. Unless the USB host gives more than 500mA?

May we ask what kind of circuits .

Well, there are several, but I'd rather not cause any over-excitement or over sell myself when I'm still in the early stages of the project... all in good time.

If you read what I've asked you can probably have a pretty good guess as to at least some of what I'm doing...

 

[Squidge]

The power switch protecting the USB host is designed for 500mA continuous and 750mA peaks. However, for an internal circuit, you could go on the other side of this protection, then you'll have 800mA - 1A depending on battery charge, but obviously 500mA of that will be reserved for USB host, then you have other components which will be running from the 5V feed.

With a full battery, you shouldn't have a problem, but I don't know what else runs off the 5V supply, so I'd be conservative in your power usage - perhaps keeping it below 100mA ?

 

[EdCa22]

The power switch protecting the USB host is designed for 500mA continuous and 750mA peaks. However, for an internal circuit, you could go on the other side of this protection, then you'll have 800mA - 1A depending on battery charge, but obviously 500mA of that will be reserved for USB host, then you have other components which will be running from the 5V feed.

With a full battery, you shouldn't have a problem, but I don't know what else runs off the 5V supply, so I'd be conservative in your power usage - perhaps keeping it below 100mA ?

Hmmm. I need at least 200mA, likely a bit more. I guess this should be possible with a full charge. And in fact the main part of what I want to do is most likely to be used when the pandora is near a mains socket already. Have we any idea of what is already running from the 5V supply, other than USB?

Thanks Squidge

 

[Phawx]

Is this GPS?

 

[EdCa22]

Is this GPS?

It wont be anything if the information doesn't become available... *hint* *hint* *nudge* *nudge*

 

[craigix]

A GPS Usb stick might be easier?

 

[EdCa22]

A GPS Usb stick might be easier?

I'm not after GPS though

 

[peca]

I guess that there must be somewhere must be output from power management circuit. I mean output that is switched when device goes on/off. In worst scenario: Solder it directly on battery connector and use some other source (ie USB port) as controlling line for electronic switch. (sorry if not understandable - lack of English knowledge)

 

[Pleng]

Is this GPS?

I don't think it's GPS because of this line:

QUOTE

And in fact the main part of what I want to do is most likely to be used when the pandora is near a mains socket already



My guess is Ethernet.

 

[Squidge]

My guess is Ethernet.

Why bother with internal if thats the case? If its sitting on the desk, having a USB Ethernet adaptor connected to it isn't exactly going to bother that many people...

Plus, if the Pandora is near a PC, you can do ethernet over USB via the OTG connector.

 

[EdCa22]

So any word on LCD pin out and connector? And signal levels? Datasheet for the LCD would do