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isavitsky edited this page Sep 30, 2018 · 3 revisions

433T30D LoRa KISS TNC wiki

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Case top:

Case top

Case bottom:

Case bottom

To install the firmware:

  1. Disassemble the unit.
  2. Solder four wires for ST-LINK SWIM: PCB SWIM
  3. Flash the STM8L-433T30D-TNC.hex file with ST-LINK flasher.
  4. Connect module AUX output to DB-9 pin 7 (RTS).

If you're not going to use DB-9 RS-232 port, but TTL UART instead, you can use 4-pin RS-485 connector for this purpose. You will need to remove the VCC diode and two yellow Y capacitors and solder three wire bridges from 433T30D module TX, RX and AUX pins to the RS-485 outlet.

Unit setup

Use M0 switch for switching between the setup and operation modes. Setup is entered by putting the M0 down. Connect the serial terminal programme to the appropriate serial port with 9600/8/N/1, no flow control.

Welcome screen indicates "Semtech chip id: 0x12" which tells that MCU is able to communicate with the Semtech chip. Value of 0x00 indicates a hardware error.

  1. A first step is to initialise the EEPROM by selecting menue item 3.
  2. A second step is Basic settings. Transparent serial bridge is meant to be operated point-to-point, so TX delay, P-parameter and slot time are irrelevant. In KISS mode good values to start with are: TxDelay = 1, P-parameter = 63 and SlotTime = 10 in multipoint mode and TxDelay = 0, P-parameter = 255 in point-to-point mode (SlotTime is irrelevant in this case). All devices in the network should have the same spreading factor, modulation bandwidth and preamble (advanced settings) unless SF=6, where same coding rate should be set same as well. With SF=7—12 coding rate is determined automatically.
  3. A third step is advanced settings. In advanced settings it is required to select PA_BOOST in PaConfig and set the required power. The other important thing is to choose a right preamble length in item 4. Here are the good values to start with:
Modulation BW Preamble
7.8 kHz 5
10.4 kHz 5
15.6 kHz 5
20.8 kHz 6
31.25 kHz 6
41.7 kHz 6
62.5 kHz 7
125 kHz 8
250 kHz 16
500 kHz 32

Play around these values for best performance in particular RF environment.

Unit operation

For robust operation it is needed to turn on the serial port hardware flow control otherwise data loss is inevitable.

Use M1 switch to change RTS polarity. Generally, M1 up is for TTL UART and M1 down for RS-232.

RF chat in transparent serial bridge mode:

$ screen <serial tty device> <chosen serial port speed>

Ctrl-a-c

$ sudo stty -F <serial tty device> crtscts

Ctrl-d

PPPd in transparent serial bridge mode:

$ sudo pppd <IP1>:<IP2> <serial port tty> <serial port speed> noauth nodefaultroute mru 298 nodetach local debug noccp lcp-echo-failure 10 nodeflate lcp-echo-interval 300

In KISS mode:

$ sudo stty -F <serial tty device> <chosen serial port speed> raw crtscts
$ sudo kissattach <serial tty device> <AX.25 port> [IP address]
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