RTL_433 on TTGO Lora SX1728 v1

I have several “TTGO LORA SX1278 ESP32 0.96 OLED 16 Mt bytes (128 Mt bit) 433Mhz …” board that I got many years ago that I was hoping to get setup to capture a temperature sensor (LaCrosse-TX141THBv2) that is running on 433 MHz. I can capture it in RTL_433 with an RTL_SDR receiver but have yet to see if on the TTGO board.

It looks like about a year ago there was similar work being done, Starting with Lilygo TTGO 433. I followed that to setup and build my own firmware as it looks like there isn’t currently an RTL_433 build for the v1 board.

From the log I am getting looks like the RLT_433 has been initialized, but it doesn’t look like it is seeing the sensor.

N: RF Config not found using default
N: Enable RTL_433 Receiver: 433.92Mhz
rtl_433_ESP(7): Average RSSI Signal -90 dbm, adjusted RSSI Threshold -81, samples 50000

Are there any good diagnostic logs I can enable? Or other good debug steps?

What is the difference between the define “ARDUINO_TTGO_LoRa32_V1” and “WIFI_LoRa_32”? I couldn’t find any specific references to what those two would be and it looks like some of the libraries use the “WIFI_LoRa_32”.

The difference may be the pins allocation to the LoRa module; I encourage you to check the pins_arduino.h file of each board:

To check which one matches your board.

Thanks! I think I made progress, but I’ll leave a couple breadcrumbs if others come across this trying to figure out their board.

I am using the Gitpod and it has been a little bit of a pain searching though the code up there. However, looking through “espressif/arduino-esp32” and “NorthernMan54/rtl_433_ESP” my best guess is that the “WIFI_LoRa_32” is actually some Heltec variant not the LilyGo one. And I’m not really seeing anyone use the “ARDUINO_TTGO_LoRa32_V1”. Since I am specifying the SX1278 variant and the pinout, it doesn’t think these should matter.

I enabled “RF_MODULE_INIT_STATUS”, “OOK_MODULATION”, and “DEMOD_DEBUG” in hopes that it would give me useful information. I am able to see that the SX1278 chip is being configured with reasonable values (so the SPI interface is working). It helped me look into how it was being configured and specifically look at packet mode vs continuous mode (rtl_433 uses continuous mode). Which then makes use of the DIO0, DIO1, and DIO2 pins.

I was also seeing a bunch of lines like “rtl_433_ESP(6): Ignored Signal length: 1, Time since last bit length: 41086, Gap length: 10732, Signal RSSI: -78, Current RSSI: -95, pulses: 0, noise count: 0”. Since it was always pulses 0 and noise 0, I wondered if the data wasn’t being transmitted to the ESP chip. In continuous mode, the DIO1 pin is the clock, and the DIO2 pin is the data. The data doesn’t come over the SPI interface like I had originally assumed. I have yet to be able to find a schematic for my board (the closest I could find is the v1.3 boards, which does have those pins hooked up. Unfortunately, it looks like the v1 board has a 32khz crystal on those pins instead of hooking up the extra DIO lines.

So next step is to try to remove the crystal and wire up the DIO1 and DIO2 lines. But that will take a couple days to get to so I figured I would leave my notes here.