FTDI Cable Hardware Flow Control Lines, 5V line?

[Andrew Instone-Cowie]

So my eBay FTDI cable arrived with its pins wired in some random order, so I've fished them out of the inline socket to sort them out. Looking at the SIO/2 schematic I see that the RTS line is wired back to the SIO/2, is this actually needed or used? Do I need any more than just Rx/Tx/Gnd? I'm powering the system from a wall wart DC supply to the barrel jack, 7805 regulator fitted.

Which brings me to the Pi Zero board and the 5V line... I haven't built thie Pi board yet, but on the SIO/2 board there are jumpers (which I have left open) to disconnect the FTDI 5v from the board. The FTDI header on the Pi board seems to be permanently wired to the 5v line. Should a jumper be provided for this? I plan to run CP/M (haven't built that board yet either...) so as I understand it I will need an FTDI connection option for uploading?

Thanks
Andrew

[David Lee]

7805 regulator fitted.

I recommend reading up on previous discussion threads about the 7805. Since it's a linear regulator, the 7805 can get quite hot depending on your supply voltage and current draw. The ezsbc psu5a is a pretty neat switching reg. solution that comes in a 7805 package: https://www.ezsbc.com/index.php/products/psu5-28.html That said, most appear to just use a wall wart that puts out 5v instead.

 

The FTDI header on the Pi board seems to be permanently wired to the 5v line. Should a jumper be provided for this?

I noticed this too. I just used the FTDI connectors on the serial board instead. I'm not a fan of powering the rc2014 from the cheensy FTDI boards I use.

I will need an FTDI connection option for uploading?

 

Without burning roms or something esoteric with ide or compact flash, you'll need to use serial. By the way, I don't recommend starting out trying to use the rpi display board until you have serial working on it's own first. You'll need serial to be working anyways before the rpi will work and the rx/tx jumpers on the rpi just add another step to debugging serial issues.

[Andrew Instone-Cowie]

Thanks, that's pretty much where I was headed - get the core set of 5 boards up and running before looking at the fancy stuff. I'm monitoring input current and so far it's not a problem, and I have the DC supply set at 7.5V. I'll see how it goes and might swap the reg out for a Traco switch mode drop in replacement if it becomes a problem.

Andrew

[David Lee]

Cool. At that voltage, I imagine you'll be ok.

[Marten Feldtmann]

Am Sonntag, 4. Februar 2018 21:11:45 UTC+1 schrieb Andrew Instone-Cowie:

So my eBay FTDI cable arrived with its pins wired in some random order, so I've fished them out of the inline socket to sort them out. Looking at the SIO/2 schematic I see that the RTS line is wired back to the SIO/2, is this actually needed or used? Do I need any more than just Rx/Tx/Gnd?

Any answer to this question ? I'v also problems about this one:

a) First      - I have to connect Rx,Tx in a crossed way - right ?
b) Second  - How do I support RTS ? Do I have to connect it to GND (at the FTDI adapter). Is this needed at all ?

Marten

 

[Jay Cotton]

maybe this will help.

http://rc2014.co.uk/wp-content/uploads/2016/07/Serial-IO-Assembly-Guide.pdf

[CubeCentral]

Looking at this:  http://rc2014.co.uk/wp-content/uploads/2017/06/SIO2.pdf

 

You are going to want to take the Tx line from your computer (probably a USB-->TTL adapter or a USB FTDI cable as I have) and feed it into the Rx line on the RC2014.  Then the Rx line from your computer into the Tx line on the RC2014.  Ground goes to ground.

I have found that the RTS signal *is* used and is crucial for getting things like XMODEM to work properly.  It should be fed into the CTS signal on the computer.

 

That FTDI cable I have plugs right into the SIO/2 board and works without issue.  If you follow its pinout, you should end up with a properly working cable.  (however they label their RTS line wrong I think it should be DTR)  Sparkfun says that it has the same pinout as this breakout, so the order is GND, CTS, 5V, TXD, RXD, DTR.

 

Be sure to remove the jumper marked 5V on the SIO/2 if you’re powering your RC2014 from the barrel jack or some other power source.  Otherwise, with the jumper in place, you may power the RC2014 through the FTDI connection from your computer’s USB.

 

I hope this helps, please let me know if you’ve additional questions.

 

    -Randal   (at CubeCentral)

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[Marten Feldtmann]

Now that makes sense ... my FTDI adapter had no CTS/DTR signals ,... just ordered a better one ,,,,

Marten