Connecting Mac to Altair-Duino via USB

[Greg Lovekamp]

I have the simplest question in the world: how can I use my Mac to connect to my Altair-Duino via USB? I have followed what I have found online.

• Connect cable.
  
• From terminal, determine /dev entry; appears to be /dev/tty.usbmodemXXXX (it comes and goes with cable being connected/unconnected and XXXX changes when doing so
  
• Use “screen” command: screen /dev/tty.usbmodemXXXX 115200

I’m supposed to see some message, but I get nothing. If I use switches to load and run BASIC on Altair-Duino, LEDs flash as expected, but I get nothing on my Mac. For the world, it just looks like my Mac doesn’t behave as other’s do, and I have no connection.

What am I doing wrong? This is truly the simplest of things, but I can’t get it to work!

[John Galt]

what i remember is the default settings are 9600 Baud 8N1 

screen /dev/tty.usbmodemXXXX 9600

[Chris Davis]

I just tried it and it works great:

From Terminal I entered "screen /dev/cu.usbmodem14101" and it worked.  If I tried to include a baud rate it did not work.

I normally use Serial2 and it's super easy

[Chris Davis]

Oh yeah, John is correct.  The default baud rate is 9600, so "screen /dev/cu.usbmodem14101 9600" works.

[Chris Davis]

Sorry, I was assuming you were connecting to the Altair-Duino 680 (which has a default baud rate of 9600).  The Altair-Duino 8800 has a default baud rate of 115200 at the programming port of the Arduino.

Make sure you are connecting to the programming port (not the native port).  It is the USB connector closest to the Arduino power jack.

If you're absolutely sure you're connecting to the programming port, try using Serial2 (it has a free 30 day trial) or CoolTerm.

[Tom Wilson]

Isn't there also a magic power up switch combo to pick the Native USB port profile? If not, is that the default if you remove the configuration files from the SD card? 

[Chris Davis]

By default there is not a configuration to use the native USB port, but it would be easy to add one.  Unfortunately you'd first need to use a serial device of some sort to create that configuration.

The default with no configuration loaded is to use the programming USB port.

[Greg Lovekamp]

I only have ONE USB port…

[Chris Davis]

Look where you connected that USB extension to the Arduino.

[Chris Davis]

I checked your order and I see you purchased an assembled and tested unit.  So it is connected to the Programming port (unless something changed in the past five years).

Have you used this since you bought it?  Do you have another computer you can connect it to?  Does it otherwise power up when your connect it via USB?

[Greg Lovekamp]

Ah, THAT explains it. I have used the Altair-Duino, but I have always used it connected to my home network, then I’ve used telnet to access it. I have never used it connected to USB.

I was going to take it to our local vintage club meeting; we have some actual vintage machines and some replicas. So, I’ve been trying to configure it for travel where I won’t have my network. Along the way, I found an interesting shell that has jitter, screen burn in and such, and I thought “wow, that’s so much better!” So, I figured I’d skip the network all the time just for the “feel”. Oh, well.

[Tom Wilson]

It's easy enough to change. Hold Stop + Aux1 Up to access the main menu, then configure the serial port to use USB. 

Save your network setup as Preset 1 and the USB setup as Preset 2. Then you can switch between them at boot by setting the front panel switch to (right switch for network, second switch for USB) and holding DEPOSIT when you power up the Altair.

I also turn on Serial Console and Serial Input in the menu, so I can immediately see that a boot message to confirm the desired port is working. (Also, so I can use the Altair from across the room.)

[Chris Davis]

How did you select the wifi modem as the input/output device?  The default may be set up to use pins 18/19 instead of the USB port.  I would raise STOP+AUX1, reset to defaults, and save the configuration as #0.  Then when you connect to the Altair-Duino via USB it should work.