Dual Channel UART RS232-WAN Extension

This Plugin for the Andino X1, provides a DualChannel UART to the Raspberry Pi or the Arduino Controller. The WAN version has an internal connection for using a Lora WAN or 2G, 4G modem

Andino X1 - Dual Channel RS232 Extension

Overview

The Board based on the SPI Uart from NXP SC16IS752. The SPI Channel can be jumpered to the Raspberry Pi or the Arduino Controller. With the Arduino Controller time critical protocols can be implemented or a general pre processing of the data can be performed.

If the Jumper is closed the 2nd UARTs RxD is wired to the external screw terminal.

If the Jumper is open the 2nd UARTs RxD is wired to the internal connector.

External connectors

Andino X1 - Dual Channel RS232 Extension

Andino X1 - RS232 Connector Skrew Terminal

Internal connector

Andino X1 - RS232 WAN internal RS232

Installation on the Raspberry Pi

Starting sc16is752 on bootup

To start sc16is752 on bootup, append this to the /boot/config.txt file. Run

sudo nano /boot/config.txt

And add the following lines to the end of the file:

dtoverlay=spi0-2cs,cs0_pin=8,cs1_pin=12,cs0_spidev=off,cs_1_spidev=off
dtoverlay=sc16is752-spi0,int_pin=7,xtal=11059200

Save the file and quit, then reboot. After that two new Devices are available: /dev/ttySC0 and /dev/ttySC1

Testing the devices

To test device functionality, first install minicom:

sudo apt-get install minicom

For the initial setup, run

sudo minicom --setup

Enter Serial port setup

+-----[configuration]------+
| Filenames and paths      |
| File transfer protocols  |
| Serial port setup        |
| Modem and dialing        |
| Screen and keyboard      |
| Save setup as dfl        |
| Save setup as..          |
| Exit                     |
| Exit from Minicom        |
+--------------------------+

Here the modem connection can be set up. Set the serial device to either /dev/ttySC0 or /dev/ttySC1, depending on which device you want to test.

+-----------------------------------+
| A -Serial Device  : /dev/ttySC0   |
| B - Lockfile Location : /var/lock |
| C -   Callin Program  :           |
| D -  Callout Program  :           |
| E -Bps/Par/Bits   : 115200 8N1    |
| F - Hardware Flow Control : No    |
| G - Software Flow Control : No    |
|                                   |
|Change which setting?              |
+-----------------------------------+

After completing the configuration, press the Esc key to return to the main setup menu and exit. The configured device should now show up normally in minicom.

Application examples

Useful links

Forum SC16IS752 (SC16IS7XX driver) Device Tree problem
Device Tree, Overlays and Parameters
List of Overlays

Author