SC131 calls AltairDuino over WiFi

[Frank P.]

I had 3 spare ESP-01s modules, so I flashed one with David Hansel's WiFiModem firmware (originally developed to put the AltairDuino on WiFi) slightly modified for the SC131 (just some name changes). Connected it (via much level conversion, since it's 3.3V) to Serial Port B of the SC131. The SC131's TX line also needed a TTL buffer because it didn't have enough oomph to drive the level converter directly. Configured the WiFiModem FW for 38400 baud (sort of a random choice), then proceeded to use MODE.COM to set COM1: to 38400, and TALK.COM to call 192.168.1.120 (my AltairDuino). It all works (see video here: SC131 calls AltairDuino)

I also re-configured the WiFiModem FW for 115200 baud, and connected it to Serial Port A. In that mode, I was able to telnet in to the SC131 from a TeraTerm terminal using its TCP/IP connection mode (just as I'm able to do to my AltairDuino). Unfortunately, the ESP-01s does not support HW flow control, so I went back to the USB-FTDI interface for normal use.

Still, it was an interesting experiment in melding the new with the old.

[Frank P.]

Simplified "SC131 goes online"

With some help from David Hansel, I was able to slightly modify the WiFiModem firmware for the ESP-01s to disable the internal pullup on its RX serial line; Then, blatantly ignoring the prohibition on 5V signals into the GPIO pins of an ESP8266, I was able to (and remain able to - nothing blows up, at least not in the short term) drive the RX line directly from the SC131's TX line. The ESP-01 still needs a 3.3V power source, so I interposed a 5V-to-3.3V regulator between the SC131's 5V and the ESP-01. The result is now a pretty simple hookup, just two modules, the ESP-01s and the regulator. I even set the WiFiModem Hayes emulation call-out speed to 1200 baud (at s37=5) and tried atdt 75.177.156.228 (The Cave BBS) for that old-timey experience.