13 replies to this topic

[Fabien Royer]

Hi,

I'm experiencing an odd behavior using COM2 on the netduino mini.

I'm using 2 USB TTL cables on both ports:

• COM1 (pin 11 & 12): deployment / debug
• COM2 (pin 1 & 2): serial user interface

The application uses COM2 to present a user interface and to receive input. The trouble is that what I send on COM2 is not what I receive in the dumb terminal
No matter what, I always get this string of data, which kind looks like a debugger handshake string to me:

MOM#X,iTMMJCVN MEM1y=y=YH$RiQRiQRiQRiQy=EMFRiQRiQRiQRiQy=TMRiQRiQRiQRiQy= E#RiQRiQRiQRiQy=.#KRiQRiQRiQRiQy=VORiQRiQRiQRiQy=VE$RiQRiQRiQRiQy=

Using COM1 instead produces the expected output but interferes with debugging / deployment of course.

Is COM2 only capable of RS232 communication?
Do you recognize the data string coming out of COM2 above?

Suggestions?

Cheers,
-Fabien.

PS: I checked out the datasheet here: http://www.analog.co...ts/ADM3101E.pdf and I'm still not sure what to think

[soshimo]

Hi,

I'm experiencing an odd behavior using COM2 on the netduino mini.

I'm using 2 USB TTL cables on both ports:

• COM1 (pin 11 & 12): deployment / debug
• COM2 (pin 1 & 2): serial user interface

The application uses COM2 to present a user interface and to receive input. The trouble is that what I send on COM2 is not what I receive in the dumb terminal
No matter what, I always get this string of data, which kind looks like a debugger handshake string to me:

MOM#X,iTMMJCVN MEM1y=y=YH$RiQRiQRiQRiQy=EMFRiQRiQRiQRiQy=TMRiQRiQRiQRiQy= E#RiQRiQRiQRiQy=.#KRiQRiQRiQRiQy=VORiQRiQRiQRiQy=VE$RiQRiQRiQRiQy=

Using COM1 instead produces the expected output but interferes with debugging / deployment of course.

Is COM2 only capable of RS232 communication?
Do you recognize the data string coming out of COM2 above?

Suggestions?

Cheers,
-Fabien.

PS: I checked out the datasheet here: http://www.analog.co...ts/ADM3101E.pdf and I'm still not sure what to think

Isn't COM2 RS232 levels (+-12vdc)? So it might not recognize TTL (0 +5vdc).

[Chris Walker]

Fabien, COM2 is running at RS232 voltage levels (-12V to 12V DC). You'll want to grab a USB-RS232 cable (or poke D-sub jumper wires into the female end of a serial cable and then into the breadboard holes for pins 1/2 on the Netduino Mini). Chris

[Fabien Royer]

Thanks guys. I was afraid you'd say that

[Fabien Royer]

I wish there were a version of the netduino mini with 2 TTL COM ports (and zero RS232 ).


Has Secret Labs considered such an option?

[Chris Walker]

I wish there were a version of the netduino mini with 2 TTL COM ports (and zero RS232 ).


Has Secret Labs considered such an option?

Yes.

We were talking about this last night on the live chat. The Netduino Mini is scheduled to get a brother at some point...sans RS232. No firm timelines as of yet, but the more it's requested the faster it'll get to market

Chris

[soshimo]

Yes.

We were talking about this last night on the live chat. The Netduino Mini is scheduled to get a brother at some point...sans RS232. No firm timelines as of yet, but the more it's requested the faster it'll get to market

Chris

What was the thinking to have an RS232 UART? I know a lot of modern mobos don't even come with a com port (or only one) and most people these days use USB to Serial (via FTDI or a similar chipset). I know I haven't bothered with my serial cable since I retired my venerable self-built pic programmer a few years back after I finally ponied up some money for a real pic programmer (usb). Even that chip used TTL levels to program (although you needed to apply > +12vdc for high voltage programming but that was easily done using DTR tied to a transistor operating in saturation mode with +14vdc collector voltage).

[Fred]

I must admit I've not seen a serial port for many years and had to buy a USB to serial adaptor especially for the Mini. It seems far more likely that you'd need to connect to 2 TTL serial devices than a legacy RS232 one.

[AlfredBr]

What was the thinking to have an RS232 UART?

I imagine it is for form-factor compatibility with the BasicStamp II.

[Chris Walker]

What was the thinking to have an RS232 UART?

Two reasons:
1. Netduino Mini is pin-compatible with BASIC Stamp 2...so it works with a lot of existing robot kits, dev boards, etc.
2. For commercial/industrial users...many industrial control systems use RS232 as their main interface.

We're listening to your feedback,

Chris

[Quiche31]

Yes.

We were talking about this last night on the live chat. The Netduino Mini is scheduled to get a brother at some point...sans RS232. No firm timelines as of yet, but the more it's requested the faster it'll get to market

Chris

+1 from me too. I'd happily exchange an additional true TTL-UART against compatibility with BS2 on pins 1/2/3!

[soshimo]

Two reasons:
1. Netduino Mini is pin-compatible with BASIC Stamp 2...so it works with a lot of existing robot kits, dev boards, etc.
2. For commercial/industrial users...many industrial control systems use RS232 as their main interface.

We're listening to your feedback,

Chris

That actually makes a lot of sense. I understand as well why you make that the default programming interface. The idea for a related mini sans RS232 is also a great idea. Thanks and keep up the good work!

[CW2]

+1 from me too. I'd happily exchange an additional true TTL-UART against compatibility with BS2 on pins 1/2/3!

Well, I was thinking about removing the RS-232 line driver chip and connecting R_IN, R_OUT resp. T_IN, T_OUT pads together. But it would not be easy, due to the size of the package and number of other SMD components around it (and I will not be able to solder it back). Maybe one of the next revisions of Netduino Mini could have solder jumpers (at the bottom?) to bypass the RS-232 level shifter.

[contractorwolf]

hey, my lack of experience in the differences in ttl vs rs232 led me here. i also assumed that although the com2 says rs232 i had assumed that i would use it just like com1, and i was wrong. am i also wrong to assume that i could just attach a MAX 232 onto the 1-4 pins and have my appropriate TTL tx and rx? i am working on a board that uses the mini and the xbee (with power regulator for 3.3v). my plan is to make a board that is about the size of the netduino plus but already has the xbee on the board so it could do zigbee (or wifi if you had the right xbee module with wifi). would a MAX 232 solve my problem and allow me to use the com2 for communication with the xbee? Thanks