A little ext breakout (SMD style)


urjaman

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With oshpark offering a 0.8mm pcb service, it is actually possible to have really cheap
breakouts (of whatever style you want) to go with the (relatively pricey) ext connectors,
but anyways posting this to show the one i designed:

https://oshpark.com/shared_projects/p6U317BA ($1.25 for 3, pick the 0.8mm thing)

that should be fairly self-explanatory little pcb, but to fill out a legend:
LO = line out
LI = line in
(-) = GND - duplicated
(+) = power out, also duplicated
(2) = UART2
(3) = UART3
R = Rx, Right or RTS
T = Tx
C = CTS or TV OUT 2 (C) (the other is Y)
L = left

the little "-" near the connector is the GND pin (for reference of orientation), anyways the side with that (and the /----\ looking line that was supposed to look like the rounded top of the connector shape) is "top" when installed on the pandora.

Oh, and thats what it looks like on an ext connector:
 
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pmprog

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Wow, very tempting. There was also a couple of other circuits I wanted to try and fab; and free international shipping is pretty amazing.

Even if I don't order the ext breakout, I'm bookmarking that site, thanks
 

TrashyMG

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Please forgive my hardware noobiness; is this enough to be able to get serial RS232 (5-pin) through the EXT port? How would I go about wiring that up?
I think you need to have some kind of level shifter to handle the transition from 5V RS232 and the 3.3V the UART on the Pandora. I know the MAX3232 is often used for this.
 

HelenF

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The Pandora UART and other IO pins are 1.8V, while the power out on the EXT connector is 2.8V, which makes things awkward for level shifting. What kind of circuits are people using for that?

The EXT connectors themselves are also mechanically rather fragile. The way the official TV-out cables are fixed somewhat improves the situation, but we can't really do that by hand, and IIRC some people have still broken them in normal use.

If you just want 5V serial, the easiest way is probably with an FTDI board or cable on the USB. I haven't used the hardware flow control on those, but they have pins for it.
 

HelenF

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The A port tracks VCCA and the B port tracks VCCB, with VCCA<=VCCB. So I guess you feed VCCA with an IO pin? That might be OK since the A side doesn't need to drive anything much.
 

levi

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Hmm, I thought the first Pandora software was developed using a serial connection to the board, before decent cases existed. I presume that went through the EXT port, and guessed it was kind of straightforward, but I guess I guessed wrong.
 

urjaman

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They made "one-off" huge ext boards for that... look it up in the wiki. (with IIRC an RS232 conversion chip that could understand the 1.8V logic and 2.8V power... expensive chips those).


Anyways I have a FT232RL circuit that i've proven works for pandora-uart to usb (for PC to debug with), thats just a 1.8V regulator for VCCIO and otherwise normal FT232RL stuff.
Just if you want to know what it looks like: https://oshpark.com/shared_projects/lyjx67CA

I also have plans for a ch340g based circuit (=> bulk cheap pandora boot/kernel debug thingies), but you dont get to see that yet :p (i havent built/tested it yet).

EDIT: cant be bothered to make a seperate answer but i didnt mean that FT232RLs are cheap :p, expensive chips too...
 
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frefol

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The chip that was used on the breakout board is the MAX3381E which looks like it's about as much as the FT232RL. Of course if you were going to make an adapter the FT232RL chip would be much more convenient than the MAX3381E, unless you really want the RS232 instead of USB connection.
 

levi

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USB would probably be more convenient for me these days, as I'd only have to invest in a USB to RS232 adaptor or see if I can find an old PCI serial card in my old bits box(es). If RS232 isn't easily adapted USB does make more sense. Searching for that part on my local monopoly internet bookshop shows that many people are selling adaptors for Arduino type boards that include that chip - I wonder if that would be a cheapish way to build an EXT to USB interface.
 

HelenF

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We also get a virtual serial connection with g_cdc when plugging the Pandora's mini USB into a PC. The port is /dev/ttyGS0 on the Pandora and /dev/ttyACMx on my Fedora machine.
 

TrashyMG

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We also get a virtual serial connection with g_cdc when plugging the Pandora's mini USB into a PC. The port is /dev/ttyGS0 on the Pandora and /dev/ttyACMx on my Fedora machine.
Which currently only gets you to the u-boot prompt if you select usb serial in the boot menu. I'm sure it could be enabled for use as a regular serial linux terminal.
 

urjaman

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Hey all, this thread has now become "urjamans ext port things" :p, but as i mentioned the simpler serial port adapter i was working on (has a ch340g usb serial chip), it's now as ready as it'll ever be, as in built and tested.

This is what it looks like:
assembled-chpndser.jpg


https://github.com/urjaman/chpndser has the pcb design files (also shared at https://oshpark.com/shared_projects/jlOmwnKj )

but my real question is, would anyone want these? lets say if the price was 20€ for the whole thing?
I do have the parts (except pcbs (have 3) and ext connectors (have 2)) for like 15 of these...

(remember, ED is taking 7€-and-shippings for the connector alone, and this thing is rather fiddly to solder together... maybe i could do 10€ without ext connector).
 

kuru

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I wish I had that little PCB when I destroyed half of my connectors while trying to solder TV out cables.. without flux agent, using just a gas driven soldering iron D:
Cool stuff.
 

urjaman

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Yeah I'm still here, but if you want a faster reply than this (ingoreis got a pm... very late), maybe use other methods than mentioning in the thread (PM me, i think that should make an email notification, or find me on irc or something...)
 

ingoreis

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Hi they arrived Fine.
Very good Work and stable soldered.
Fine with MiniUsb Plug instead MicroUSB.
Thank you because i love MiniUSB much more.


But a few Questions from me:

What i do exactly with this?
-is it an access for the Jtag?
-can i use a OTG Mouse Too on this USB Port?
-what happen when i connect a Charger on this?
-is this a Serial Output for Debugging Things?
And when yes how can i access it on a Windows PC?
-can i use it with an IR Diode for sending IR Signals over Serial connetion to Remote my TV or BluRayPlayer?
-was it USB 1.1? Or 2.0 too?

-is it rekognized automatic @ Boot or do i have to modprobe some Things in Terminal before Using?

I know i must experiment with this but bit knowing before experimenting is ever better :D


Last Question:
Is it possible that you build the Same with Remote Infrared Diodes?

A Dream of me is to use the Pandora as a TV Remote Control.
Your genious Adapters can maybe fulfill this Whish for me and others.
We have an long long German Thread about this in the German Pandora Forum.

Thanks for your Advice :D
 
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