Main Site Documentation

Serial communication


#1

Hey guys,

Is it possible to output use serial communication (COM) on domino without using a shield? Something like directly using pins?

I know you can use pins as COM out and COM in. But let’s say I would like to connect it directly to a servo controller (which uses com) to write data to the servo controller without the need of a USB-serial cable?)

Controller:
http://www.lynxmotion.com/Product.aspx?productID=395

From the userguide (http://www.lynxmotion.com/images/html/build136.htm)

  1. This is the TTL serial port or DB9 serial port enable. Install two jumpers as illustrated below to enable the DB9 port. Install wire connectors to utilize TTL serial communication from a host microcontroller.

See unidirectional TTL serial.

Can Domino do this??

Thanks!


#2

I think this is explained in the book.

Serial interfaces can be RS232 (-12V to +12V) or TTL (0V to 5V or 0V to 3.3V). If your controller is TTL then you can connect it directly.
Our servo board is TTL for example so you can connect it directly.


#3

Wow. FEZ is SO FREAKIN’ EASY :wink:

This was almost TOO simple, hahaha.
Thanks chimp, works very good!

What I’ve done:
Connect a cable from COM1 out (Di1) to RX on the SSC-32.
Connect another cable from GND to GND on the SSC-32 (this is essential, or you will get strange signals)

Code:

class Program
    {
        public static void Main()
        {
            SerialPort UART = new SerialPort("COM1", 115200);
            UART.Open();
            int Servo = 12;
            int Position = 1500;
            while (true)
            {
                byte[] data = Encoding.UTF8.GetBytes("#" + Servo.ToString() + "P" + Position.ToString() + "T150\r");
                UART.Write(data, 0, data.Length);
                Thread.Sleep(200);
            }
        }
    }

Thanks Gus :wink:


#4

Hey gus,

Pursuant to that; can Fez support CMOS (Asynchronous) 3.3V-level signals. (Not 5V tolerant) connections?


#5

Not sure your question make sense or I am not understanding it!

CMOS = voltage levels = will work with FEZ (CMOS or TTL at 3.3V or 5V all should work)
Asynchronous = way of transferring data = UART (COM) which you have 4 on FEZ (USBizi)


#6

The FEZ output will be 3.3v , However if the interfaced device outputs 5v, the FEZ can interface without the need for a level translator.

EDIT: I did not see the reply from Gus : please read that :slight_smile:


#7

Most likely I don’t understand the technology so I’m asking incorrectly. What I want to do is to make a shield that uses a component which uses CMOS levels (MOSFETS). In the product’s integration guide they mention how it’s 3.3v levels and that you’ll need some chip or other circuit to convert TTL levels to CMOS and vica versa. But since Fez is a microcontroller it’s got to be using CMOS levels already, right? Therefore on the FezDomino the COM port pins should all be CMOS levels right?

(http://www.semiconductorstore.com/pdf/newsite/Lantronix/Xport-Pro_IG.pdf pg7)


#8

In most cases, TTL will work with CMOS…I am still not sure why you are asking these questions and what is it that you are trying to make :slight_smile:

If you are a beginner in electronics, stick the components we provide on this website to get started before you start making your own components/shields


#9

Oh the purpose is to make an Ethernet shield for the Fez_Domino to offload the TCP/IP and web service work to. The reason being is that the Ethernet shield for Fez has a beta driver that is stated as unreliable.


#10

The beta is the software driver and not the board itself. We have Ethernet shield already and there are tens of these already out there for Arduino that would just work with FEZ Domino!

You making a new board will not give you any benefit at all