Example_V10RPiV2 - fablab-wue/piTelex GitHub Wiki

Second Example with V.10 at Raspberry Pi, using GPIO lines and a MAX232 line driver

The schematics design is based on MAX232 chip to support the full V.10 specification (without negative voltage hack).

  • Main features:

    • correct V.10 voltage level
    • wired-or (2 diodes and resistor) for printing own typed characters in red and incoming characters in black

  • Additional (optional) features:

    • I2C connector
    • NeoPixel connector
    • 1 user-button connector (medium cable length)
    • off-button connector (short cable length)
    • duo-color-LED to show the connection status
    • SSR connector for power saving
    • reconfigurable (solder pads) for V.24 with TXD, RXD, RTS, CTS

Hardware

All you need is a Raspberry Pi, a MAX232 as driver and a hand full of resistors, capacitors and diodes.

Schematics

Connectors

J6 - V.10 (V.24) to teletype
Pin Name Pin DSub V.10 Name Comment
1 GND 7 + 9 + 11 E1, E21, E22
2 +5V - - not used
3 RXD 2 D1 from teletype to RPi
4 TXD 3 D2 from RPi to teletype
5 CTS 4 S2 status/observe line. Goes to high if teletype is in LIN-mode
6 RTS - - not used

Jumpers

No. Use
1,3 select GPIO input lines for RXD/TXD
2 enable/disable hardware loopback
4 select full (+/- 9V) or reduced (+/-6V] V.10 voltage
5 enabale/disable external power relay (SSR)

Printed circuit board

A PCB is available for the above schematics:

The PCB data be dowloaded from https://github.com/fablab-wue/piTelex.supplement/blob/master/PCB_KiCad/piTelex_V10_1.0.0/

Software

For piTelex installation see SW_Install

This adapter is handled by the software module RPiTTY.

The settings in the file telex.json have to be adapted:

    # TeKaDe FS200 or FS220 over V.10 interface (new pinout)
    "RPiTTY_FS200_V10_new": {
      "type": "RPiTTY",
      "enable": true,
      "mode": "V10",
      "pin_txd": 27,               # Pin13
      "pin_rxd": 17,               # Pin11
      "pin_relay": 0,
      "inv_relay": true,
      "pin_power": 9,              # Pin21
      "inv_power": false,
      "use_observe_line": true,
      "pin_observe_line": 22,      # Pin15
      "inv_observe_line": true,
      "nZZ_observe_line": true,
      "baudrate": 200,             # 50, 75, 100, 200
      "coding": 0,                 # 0=ITA2
      "loopback": false
    },