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Building a JP1 cable
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paoleela



Joined: 22 Nov 2012
Posts: 33
Location: Germany

PostPosted: Mon Jan 14, 2013 7:56 am    Post subject: Reply with quote

I found a picture with colors like my cable has: IMG. I'm going to use this mapping compared to the one in the cable hack pdf. Is there any chance to break something in the remote if wrong wired?

As for the kernel module I got ftdi_sio working and creating a device for my USB adapter.
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binky123
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Joined: 14 Feb 2004
Posts: 1292

PostPosted: Mon Jan 14, 2013 3:22 pm    Post subject: Reply with quote

Linux should create a /dev/ttyUSB0 for you.

The only important signals are Reset, TX, RX, GND on the JP1 connector so you can leave the rest unconnected.

You can manually reset the remote and then only connect TX,RX,GND and see if you can get an ID from the remote. If not, switch TX,RX and try again.
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paoleela



Joined: 22 Nov 2012
Posts: 33
Location: Germany

PostPosted: Tue Jan 15, 2013 5:09 am    Post subject: Reply with quote

I'm quite confused now.
"Easier Building the FTDI Interface.pdf" shows a 2x3 connector with only 4 wires connected into 2,3,4,6. This should be a JP1.2/3 cable.

"FTDI cable hack.pdf" finally shows a 2+3 connector but I can't see the final wiring, only a black one. Anyway the colors are completely different for my cable, maybe the black one is the same. But even the black has a different position in the 6x1 connector in my picture than it has in the "Easier Building...pdf".

Now you say I only need 3 eonnectors at all? What about the 4th? Is it possible to determine at least the GND or TX by a voltage meter or something?
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binky123
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Joined: 14 Feb 2004
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PostPosted: Tue Jan 15, 2013 1:03 pm    Post subject: Reply with quote

You need 4 wires. I only mentioned a method to reduce the number of wires to help with wire identification. You can put the remote into "Reset" mode where it is non-responsive to any button presses. After it is in the "Reset" mode, you can communicate with it using the TX,RX wires.

You can probably use a terminal program like minicom to send characters to the serial port and the voltage should fluctuate on the TX line. You can even loop it back into the RX line to see the echo.

Are you able to trace the wires back to the chip? Some terminal programs will allow you access to the other serial lines(CTS,RTS,DTR). You can probably use those features to determine which wire goes to which line.
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underquark
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Joined: 20 Jun 2005
Posts: 871
Location: UK

PostPosted: Thu Jan 17, 2013 11:41 am    Post subject: Reply with quote

I have edited the "FTDI cable hack.pdf" file to better show the final position of the wires. Download link.

Note that those colours only hold true for the genuine FTDI cable, i.e. the one that I ordered and cut up and have got working satisfactorily. I don't have much in the way of test equipment but I plugged my cable into a USB socket and measured various connections with a multimeter and got the following:

Code:

Neg       Pos       Voltage
Black     Yellow    2.98
Black     Red       3.38
Black     Green     3.38
Black     Orange    2.98
Black     Brown     2.98


and not a lot else between other wire pairs, so if your black wire (or another) gives similar voltages on other wires this might help you narrow it down a bit.
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grubia



Joined: 20 Jan 2013
Posts: 1

PostPosted: Mon Jan 21, 2013 5:58 am    Post subject: Reply with quote

binky123 wrote:
Linux should create a /dev/ttyUSB0 for you.

The only important signals are Reset, TX, RX, GND on the JP1 connector so you can leave the rest unconnected.

You can manually reset the remote and then only connect TX,RX,GND and see if you can get an ID from the remote. If not, switch TX,RX and try again.

Hi, can you please tell me how to put remote manually in reset mode ?
I have several usb serial adapters with ttl levels and only tx, rx, gnd, 3.3, 5v outputs. I was thinking about soldering wire directly to the rts pin of the chip since it is there, but if there is easier sollution ...
Will shorting pin 1 and 2 (directly or trough 4.7k resistor) put remote in reset mode ?
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binky123
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Joined: 14 Feb 2004
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PostPosted: Tue Jan 22, 2013 12:20 am    Post subject: Reply with quote

On power up or restart, the remote will go into "serial communication" mode if IDC-4 RX is grounded for 100ms.
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underquark
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Joined: 20 Jun 2005
Posts: 871
Location: UK

PostPosted: Tue Jan 22, 2013 5:29 am    Post subject: Reply with quote

Trial and error suggestion:

Get a multimeter and set it to a suitable voltage range (e.g. 20V DC). Let's start testing with the Black wire as we may strike lucky. Stick your Negative probe onto the black wire and start probing the other wires with the Positive.

If you get readings from all the other wires of the order of 2.98V and 3.38V like mine then you can assume that the Black wire in your cable is the same as that in the FTDI cable. Furthermore, you will have narrowed down the other wires into two groups - the Red and Green reading 3.38V and the Yellow, Orange, Brown reading 2.98V.

If you only get a reading from one of the wires then assume that this other wire corresponds to the FTDI Black wire. Now repeat the test treating it as the Black wire and take note of the voltages from the other wires.

Label your wires somehow so that you can identify which one should be called "Black" and which ones are "Red/Green" and "Yellow/Orange/Brown"

You're looking to get four wires from six in the correct order. There are 360 ways to arrange four wires from six BUT you now know one of those wires is Black so that leaves you looking for three wires from five which reduces the combinations down to 120.

You can further reduce this number as you know that the wires fall into three groups:
a] The known or designated Black wire
b] The 3.38V wires Red and Green
c] The 2.98V wires Yellow, Orange, Brown

Now you know that the wires can only go in certain positions in the connector block. Let's assign letters to those positions according to the FTDI cable colours:
K Black
G Green
O Orange
Y Yellow

Let's number your wires 1 thru 6:
(NB - substitute your colours for the ones listed here)
1 Black (Negative on you test)
2 Red (3.38V)
3 Green (3.38V)
4 Yellow (2.98V)
5 Orange (2.98V)
6 Brown (2.98V)

We have already identified which wire should be treated as Black (Wire #1) so it goes into the Black slot. That just leaves us with 3 slots to fill with 3 from 5 wires and the combinations are as follows:

Code:

K     G     O     Y
1     2     4     5
1     2     4     6
1     2     5     4
1     2     5     6
1     2     6     4
1     2     6     5
1     3     4     5
1     3     4     6
1     3     5     4
1     3     5     6
1     3     6     4
1     3     6     5


Now, if I've worked this out correctly that only leaves 12 combinations for you to try out, providing that you have identified the Black wire and decided which of the two groups (higher or lower voltage) that the other wires belong to.
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3FG
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Joined: 19 May 2009
Posts: 3246

PostPosted: Sun Jan 27, 2013 10:44 am    Post subject: Reply with quote

A similar eBay listing mentioned here provides the following:
Code:
1 - Black:GND
2 - Blue:CTS
3 - Red:5V
4 - Green:TXD
5 - White:RXD
6 - Yellow:RTS

The photographs in the two listings look identical and the descriptions are identical, except that one has appended the definitions for the wire colors. I guess that wire #3 (red) actually outputs 3.3 volts rather than 5, but that should be checked.
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paoleela



Joined: 22 Nov 2012
Posts: 33
Location: Germany

PostPosted: Tue Feb 05, 2013 3:34 am    Post subject: Reply with quote

Wow just read the last answers now, got no reminder about new post though I'm watching this thread...
I'm going to work through these hints. However I found some other data spec document about a similar cable: FTDI_-_SERIAL_CONVERTER_CABLE_TTL232R.pdf
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