5 units working, not synchronized in time or transmissions, that is for later Exercise

exercises/01_lora_ascii_pingpong/README.md

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+# Exercise: LoRa Transmission Validation (SX1262)
+
+## Overview
+
+This exercise validates raw LoRa packet transmission from the **LILYGO T-Beam SUPREME V3.0** using the onboard **SX1262** radio.
+
+The objective is to:
+
+1. Transmit deterministic LoRa packets at known parameters.
+2. Confirm successful reception using:
+
+   * A second T-Beam
+   * A Waveshare SX1303 concentrator sniffer
+   * Or any SDR/LoRa receiver configured with identical PHY settings
+3. Verify correct alignment of frequency, spreading factor, bandwidth, and coding rate.
+
+This is a **PHY-layer validation exercise**, not LoRaWAN.
+
+---
+
+## Hardware
+
+### Transmitter
+
+* Board: **LILYGO T-Beam SUPREME V3.0**
+* MCU: ESP32-S3
+* Radio: SX1262
+* Antenna: 915 MHz tuned antenna
+* Power: USB-C or 18650 battery
+
+### Receiver / Sniffer
+
+Any device capable of raw LoRa reception with manual PHY configuration:
+
+* Second T-Beam (SX1262)
+* Waveshare SX1303 + `lora_pkt_fwd`
+* SDR with LoRa demodulator
+
+---
+
+## LoRa Radio Specifications
+
+The sniffer **must** match these parameters exactly.
+
+| Parameter        | Value              |
+| ---------------- | ------------------ |
+| Radio Chip       | SX1262             |
+| Frequency        | **915.000 MHz**    |
+| Modulation       | LoRa               |
+| Bandwidth        | **125 kHz**        |
+| Spreading Factor | **SF8**            |
+| Coding Rate      | **4/5**            |
+| Preamble Length  | 8 symbols          |
+| Sync Word        | 0x12 (Public LoRa) |
+| CRC              | Enabled            |
+| IQ Inversion     | Disabled           |
+| Output Power     | 14 dBm (default)   |
+
+---
+
+## Important Notes for Sniffer Operators
+
+### 1. Frequency
+
+Ensure your sniffer JSON or configuration file contains:
+
+```
+"freq": 915000000
+```
+
+If using SX130x HAL:
+
+```
+915000000
+```
+
+No offset. No channel hopping.
+
+---
+
+### 2. Spreading Factor
+
+Must be:
+
+```
+SF8
+```
+
+If the sniffer is set to multi-SF mode, confirm that SF8 is enabled.
+
+---
+
+### 3. Bandwidth
+
+```
+125000 Hz
+```
+
+Not 250 kHz. Not 500 kHz.
+
+---
+
+### 4. Coding Rate
+
+```
+4/5
+```
+
+Some interfaces represent this as:
+
+```
+CR = 1
+```
+
+---
+
+### 5. Sync Word
+
+If your sniffer filters on sync word:
+
+```
+0x12
+```
+
+This is the public LoRa sync word (not LoRaWAN private).
+
+---
+
+## Expected Packet Behavior
+
+The transmitter:
+
+* Sends a short ASCII payload
+* Repeats at a fixed interval
+* Does not use LoRaWAN
+* Does not use encryption
+* Does not use MAC layer framing
+
+Sniffer output should display:
+
+* RSSI
+* SNR
+* SF8
+* BW125
+* Payload length matching transmitter
+
+---
+
+## Confirming Correct Alignment
+
+A properly aligned sniffer will show:
+
+* Stable RSSI
+* Correct SF detection (SF8)
+* Clean CRC pass
+* No excessive packet loss at short range
+
+If you see:
+
+* No packets → Check frequency mismatch first.
+* Packets but CRC fail → Check bandwidth mismatch.
+* Packets only intermittently → Check spreading factor.
+
+---
+
+## SX1262 SPI Mapping (T-Beam SUPREME)
+
+For reference, the radio is connected as follows:
+
+| Signal | ESP32-S3 Pin |
+| ------ | ------------ |
+| SCK    | 12           |
+| MISO   | 13           |
+| MOSI   | 11           |
+| CS     | 10           |
+| RESET  | 5            |
+| BUSY   | 4            |
+| DIO1   | 1            |
+
+These match the board’s hardware routing.
+
+---
+
+## Build & Flash
+
+### PlatformIO
+
+1. Open project folder
+2. Select correct environment
+3. Compile
+4. Upload via USB-C
+5. Monitor serial output
+
+### Arduino IDE
+
+* Board: ESP32S3 Dev Module
+* Flash: 8MB
+* PSRAM: QSPI
+* Upload speed: 921600
+* USB Mode: CDC and JTAG
+
+---
+
+## Purpose of This Exercise
+
+This exercise verifies:
+
+* SPI communication with SX1262
+* Radio configuration correctness
+* Antenna functionality
+* Sniffer alignment
+* Baseline RF performance
+
+It is intended as the foundational RF validation step before:
+
+* Reticulum interface integration
+* microReticulum radio abstraction
+* LoRa time-synchronized experiments
+* Multi-node field testing
+
+---
+
+## If You Cannot See Packets
+
+Work through this checklist:
+
+1. Confirm antenna attached.
+2. Confirm sniffer at 915 MHz.
+3. Confirm SF8.
+4. Confirm BW125.
+5. Reduce distance to < 2 meters.
+6. Increase TX power to 17–20 dBm for testing.
+7. Confirm no regional regulatory lock mismatch.
+
+---
+
+## Relationship to `main.cpp`
+
+This README corresponds to the current exercise implementation in:
+
+```
+main.cpp
+```
+
+See source for definitive parameter values 
+
+If you modify radio parameters in code, update this README accordingly.
+
+