Shadow Dash USB via FTDI cable - RS232 end question

[walterclark1]

I have SD 1.20, a USB OTG cable for the Samsung Galaxy S4, and an FTDI UC232-R adapter cable.

I have been using Bluetooth to the MS3 with the Bluetooth RS232 adapter configured and sold by EFI Analytics. To power that adapter I have 5V on the MS3 RS232 connector pin 9. THE FTDI adapter shows pin 9 used (optionally) as RI. I want to try using the USB connection because a tablet I am looking to get to dedicate to Shadow Dash doesnt have BT so I want to get the USB functionality tested on a working device (the S4) first then move to the tablet..and maybe modify a dedicated FTDI adapter to take power from the MS3 via the DB9 instead of the tablet via USB. Can I assume connecting this unmodified FTDI cable to my MS3 DB9 connector with pin 9 still supplying 5V will not be a problem for the adapter cable? Thanks.

[walterclark1]

I decided to mod my existing FTDI cable - the US232R to power it from the MS3 DB9 pin 9 and disconnect the 5V USB input. It works with my known device - the Galaxy S4 and add-on OTG cable. So I can use it for testing when the tablet(s) arrive.

The cable I am using is made by FTDI and puts the chipset in the DB9 connector end. This makes the RS232 cable length and the USB end about a meter.

If I understand one of the rationalizations for going with a RS232-USB solution for Shadow Dash rather than just using the existing (on the MS3 fitted Megasquirt anyway) native USB it is the better noise immunity of the RS232 in an automotive - esp. race car - environment. Assuming that to be true, the cable I am testing with is configured backwards from what would be helpful. I would want an FTDI cable with the chipset at the USB end and the RS232 cable running to the MS RS232 port. So assuming that to be the case, anyone know if the cable sold at EFI Analytics one with the chipset at the USB end? I know FTDI sells complete and partial cables and well as modules either way, but the EFI Analytics unit is priced so as to make buying anything else (complete or partial cables, or modules) rather pointless unless one desired a different physical configuration.

[LT401Vette]

The cable from EFI Analytics has the chipset at the RS232 end, but uses a well shielded USB cable that is only 3ft long. So I haven't seen anyone with noise problems when using it. So I wouldn't worry, even in a race car.
However, if you want to go with almost all RS232; The USB to RS232 adapter that DIY Autotune sells is more of a straight adapter. You should discard the USB cable that comes with it, then you can run pretty close to all RS232 if you plug the OTG cable directly into the adapter then run RS232 the rest of the length.
You will still be USB in the OTG cable, but they are only a few inches long, not generally very well shielded though.

Using either of the above, If you have noise issues it is probably going to be from the OTG cable, but I haven't seen to many troubles there.

[walterclark1]

Thanks Phil.

I fiddled a little with this again this AM. In particular I wanted to know a bit more about the USB on the MS3 board. I opened my MS box and found out it is an FT232R chip with its power coming from the USB connector. This last little bit is probably why some Android devices dont work with the USB port...They dont always supply +5V in OTG mode even thought they are acting as the host. I think that is permitted within one of the protocols called SRP. I know my Galaxy S4, thru its OTG cable does not provide 5V to any of the peripherals I have such as memory sticks, the FTDI USB-RS232 cable and the MS's FT232R chip. My guess is that this is fairly common.

I decided to mod an old but good USB A-B cable to check the S4 to FT232R path out. I clipped the power wire in the cable near the USB B end and soldered the bit from the B end to pin 9 of a DB9 to plug into the MS serial port and pick up 5V for the FT232R chip. I put an OTG adapter on the A end and connected it to my S4. Seems to work the same with Shadow Dash as the RS232-USB cable I mentioned earlier.

One of the Android tablets I have coming to evaluate as a possible "dashboard" uses a mini-B USB rather than the more common, among Android devices, micro-B. All of the ones I am considering also have separate DC charge inputs so I can avoid the OTB/USB charge mess. Once I settle on a tablet, I plan to make up a USB cable from one of the USB A-B cables I have already (all very good ones - made surplus when my wife retired her private practice). I will 1) add a 3rd - electrostatic - shield, grounded only at the MS end 2) get power for the FTDI chip from the MS DB9 pin 9 if the tablet doesnt provide it in OTG mode, 3) eliminate the "OTG adapter" with a configured mini or micro plug. From what I can tell the only thing an "OTG adapter" does is tie the mini/micro B pin 4 to pin 5/Ground to tell the Android device it is now supposed to be a host. I have extra of both types of plugs from other projects.

If I am not happy with the USB noise margins I will go with RS232 from the MS DB9 to an FTDI module at the tablet with a mini or micro B plug in place of the standard A plug so it can plug directly into the tablet USB. The module will be powered by either the tablet or MS depending on the tablet.

Update: The particular OTG adapter I got for the S4 is not connected from the USB micro B pin 1 to the standard USB A pin 1 to supply 5V. I dont know if this was deliberate or a defect as the vendor hasnt a clue... I made up a micro B to standard B cable with the OTG pin configuration (pin 4 grounded on the micro B). S4 supplies the FT232R just fine and (at least with the engine not running) it all works fine with Shadow Dash.

[Timmerklits]

Hello,

I just bought shadow dash also.
The bluetooth adapter is from serial to bluetooth, but in this car the ECU has an USB cable coming out.
Is it possible to go from This usb to serial and then use the bluetooth adapter, or is there a bluetooth adapter with usb connection also?

[Timmerklits]

I know see that some devices also work with the usb cable.

I have here a samsung tablet what i want to try, there are adapters available from micro usb to usb from samsung itself. Will they work?
Or what will be the best way to connect to the table?

[LT401Vette]

There is no USB to bluetooth adapter that will work with USB on the controller. USB to bluetooth adapters require host mode and a driver, like on a PC. You can't do that on the MS.

If the USB port on your MS is based on an FTDI chipset and your phone supports USB host mode, then you can connect to it via USB. You will need a USB OTG cable to plug the USB into your phone.

[Timmerklits]

Hello, just received an usb otg cable from galaxyworld, plugged it into my samsung tab3 and to the car, immediately everything works well. 45 data per second. Goes as fast as on my laptop, nice.