want to use a usb cable instead of a serial cable?

nissan300sx · Post by **nissan300sx** » Sun Nov 12, 2006 12:21 pm

here we can talk about using usb cables instead of serial cables. its not terribly difficult i think. my honda ecu uses the same max323 adapter that the megasquirt has integrated on the board. i also use a motorola phone usb cable on the same exact honda ecu. its a little different setting up the com ports on your pc or laptop but i'll explain it a little more if anyone is interested

mrbell · Post by **mrbell** » Mon Nov 13, 2006 2:34 pm

I'm a bit confused as to what you are trying to do. It sounds like you're wanting to use a USB-serial adapter, which you should be able to just do, but you still need the Max232 and serial cable.
Optionally, you could build a USB-serial chip into the ECU, but it certainly seems easier(and possibly cheaper in the long run) just to use the usb-serial dongle.
If you want to use direct USB-USB communication, you'll have to put a USB controller chip into the ECU, which is fine, but USB doesn't really work like a regular serial connection. You'll have to reengineer the communcations layer on both sides...

nissan300sx · Post by **nissan300sx** » Tue Nov 14, 2006 6:45 am

im saying that instead of using the serial cable and the max232. you can connect a certain motorola phone cable directly to the rx/tx/gnd. the cable has a chip built in to it. you download the proper drivers, which i will find and post, and it will set up the motorola usb cable as a com port which you can then select as the port you are going to tune with. does this sound any better? im trying hard to make sense but im not exactly a technical super guru. i just understand whats going on in the ecu's i have tested and i am just saying i want to test it on a megasquirt, and if anyone is interested they can try it too.

mrbell · Post by **mrbell** » Tue Nov 14, 2006 9:06 am

If the USB cable shows up as a com port on the computer, then I am 99% certain that the phone has a MAX232 or equivalent in it and the cable is a USB-serial adapter. The cable or the phone could have both bits. This wouldn't gain you anything over having a standard USB-serial adapter(which can be bought at any store that carries computer peripherals), except a smaller plug. But that can be remedied in many other ways.
A better solution, having no requirements of a special cable and using all commodity hardware and standard software interfaces, would be to put a USB controller and socket onto the MS and talk direct USB.

Mk1rocco · Post by **Mk1rocco** » Tue Nov 14, 2006 9:38 am

Have a look at THIS internal USB adapter for Megasquirt sold by DIYAutotune. It'd be a bit more difficult to adapter to Microsquirt but only because Microsquirt's SMT.

nissan300sx · Post by **nissan300sx** » Sat Nov 18, 2006 8:14 am

no, its not a serial adapter because the original tx/rx signals arent even communicating like a serial connectiion until they go through the max 232, yes the prolific chip inside the usb cable is kinda like a serial/usb adapter except you just connect rx/tx/gnd on the MS board directly to the cable just like the DIYAutotune adapter. yes i have seen diyautotune's adapter but my cable only cost $10 where i live. its just a cheap alternative for people who dont have serial ports on their computers. the reason the usb cable comes up as a com port is so that it can communicate with the MS. it wouldnt automatically configure an MS ecu because the MS doesnt work like that. maybe some day there would be memory space on the MS for alternate fuel and timing maps to select from. that would be where the MS could be recognized as a storage drive and the fuel maps could just be copied to the MS memory.

The Benz Master · Post by **The Benz Master** » Mon Aug 27, 2007 6:04 pm

I was just thinking, with the now low price of the SD memory cards or simply the usb drives, it would be a cool thing to have on the megasquirt.. I dont know about faisability tho, i'm not an electronic expert.

Post by **Bruce Bowling** » Tue Aug 28, 2007 7:45 am

Mk1rocco wrote:Have a look at THIS internal USB adapter for Megasquirt sold by DIYAutotune. It'd be a bit more difficult to adapter to Microsquirt but only because Microsquirt's SMT.

The reason why uS is not USB was the connector. Right now we have a nice ampseal with the board conformal-coated. The serial Rxd and Txd coe out of the ampseal. With USB it is best to maintain cable impedance so running the signals thru the ampseal is not a great idea. This would then mean a USB connector somewhere. Trying to locate a sealed USB connector became pretty expensive. And with converter cables being so readily available (for example I can get a Prolific USB-serial adapter on Ebay for under $10.00) having uS using serial instead of USB is not a real impediment.

Having said that, notice on the uS there is a 4-pin space for a header, neat the ampseal on the top. This has +5V, Gnd, Txd, and Rxd (rs-232 levels). This can be used for a daughtercard arrangement with a USB converter chip. We are targeting this potentially for wireless comms.

- Bruce

MegaScott · Post by **MegaScott** » Tue Aug 28, 2007 9:37 am

Bruce Bowling wrote:We are targeting this potentially for wireless comms.
- Bruce

Cool!

All we need then is a Java tuning App that can interface to the Mega/Microsquirt bluetooth signal for display on the user's phone or PDA....