IFS09-TeleReceiver

IFS09-TE-TeleReceiver

Hardware design, KiCad schematics, PCB layout, and embedded firmware for the Telemetry Receiver Board of the IFS09, developed for the ISC Formula Student Racing Team (Season 2026/2027).

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Getting started

1. Create a GitHub account if you don't have one yet.

2. Download and install GitHub Desktop (beginner) or Git CLI (advanced).

   • If this is your first time using GitHub Desktop, make sure to read the User Manual.
   • If this is your first time using Git, start with a tutorial:
     • Git Tutorial
     • Atlassian Git Tutorial
   • Keep a copy of GitHub's Git Cheat Sheet handy as a reference.

3. Clone this repository to your machine:

   • SSH: git@github.com:isc-fs/IFS09-TE-TeleReceiver.git
   • HTTPS: https://github.com/isc-fs/IFS09-TE-TeleReceiver.git

How we work with this repository

Main branches

The repository follows standard ISC branching rules:

• main is the production branch. It contains only validated hardware releases, schematics, and firmware ready for track operations. Never work directly on it.
• dev (or active feature branches) is the development and integration point. Never commit directly to main — all changes arrive through a reviewed Pull Request.

main  ──────────────────●──────────────────────●──▶  (validated releases only)
                        ↑                      ↑
dev   ──────●───●───●───●───●───●───●───●───●──●──▶  (continuous integration)
            ↑   ↑       ↑   ↑   ↑       ↑   ↑
          feat/1 fix/1 feat/2 fix/2   feat/3 fix/3

Feature branches

All work — whether a new hardware revision, firmware update, or bug fix — is done on a feature branch created from dev (or main). When the work is ready, a Pull Request is opened, reviewed, merged, and the branch is deleted.

feat/<n>   →  new functionality / hardware addition (feat/1, feat/2, feat/3 ...)
fix/<n>    →  bug fix / schematic correction       (fix/1,  fix/2,  fix/3  ...)

Step-by-step workflow

1. Create the branch:

   git checkout main
   git pull origin main
   git checkout -b feat/your-feature-name

2. Work and commit:

   git add .
   git commit -m "feat(hw): add decoupling capacitors to 3.3V rail"

3. Push and open Pull Request:

   git push origin feat/your-feature-name

   Open a PR against main (or dev), verify 0 KiCad DRC/ERC errors, provide test evidence, and request review from the Telemetry Subsystem Technical Director.

1. Project Overview & System Purpose

The IFS09 Telemetry Receiver serves as the primary trackside ground-station receiving interface for the IFS09 race car. It captures high-frequency wireless telemetry frames (CAN-bus powertrain telemetry, accumulator/BMS diagnostics, suspension potentiometer data, and GPS telemetry) transmitted from the vehicle over 2.4 GHz RF, streaming uncorrupted telemetry packets over USB-Serial to the pit wall telemetry workstation.

+-----------------------------------------------------------------------------------------+
|                                     IFS09 RACE CAR                                      |
|  [Sensors & CAN Bus] ---> [ECU / VCU] ---> [Telemetry TX: nRF24L01+ PA+LNA]            |
+---------------------------------------------------+-------------------------------------+
                                                    |
                                             2.4 GHz RF Link
                                       (Trackside Line-of-Sight)
                                                    |
+---------------------------------------------------v-------------------------------------+
|                         IFS09 TELEMETRY RECEIVER (BASE STATION)                         |
|                                                                                         |
|  [External 2.4GHz Antenna] ===> [SMA Jack] ===> [nRF24L01+ PA+LNA Module]               |
|                                                        |                                |
|                                                    SPI Bus                              |
|                                                        v                                |
|                                              [Arduino Nano 3.0]                         |
|                                                 (ATmega328P)                            |
|                                                        |                                |
|                                              USB-C Serial (115200)                      |
|                                                        v                                |
|                                            [Ground Station PC / UI]                     |
+-----------------------------------------------------------------------------------------+

Key Highlights

• Processing & USB Interface: Arduino Nano 3.0 with native USB-C connector powered by the ATmega328P (16 MHz, 5V logic).
• RF Front-End: 2.4 GHz nRF24L01+ PA+LNA transceiver module with integrated Power Amplifier (PA) and Low-Noise Amplifier (LNA) for long-range sensitivity (up to $-95\text{ dBm}$ @ $250\text{ kbps}$), resolving link range constraints from prior seasons (FSA & FSS 2026).
• Antenna Interface: Edge/chassis-mountable SMA Female (Jack) connector ($50,\Omega$) matched for external 2.4 GHz high-gain omnidirectional whip antennas (or IPEX interface).
• Dedicated 3.3V LDO Regulation: On-board LM1117MP-3.3 low-dropout regulator with coupling capacitors ($10,\mu\text{F}$ input/output) providing clean, high-current 3.3 V to the transceiver independently of the Arduino Nano internal regulator.
• Status LED Indicators: Dedicated software-controlled LEDs for radio link communication activity and transceiver hardware detection.
• Testability: Dedicated test points including TP1 (nrf_power_tp) and signal test pads.
• Mechanical Integration: Four symmetric M3 mounting holes (3.2 mm drill diameter) for securing within a custom 3D-printed enclosure using M3 heat-set threaded inserts.

2. Hardware Architecture & Schematic Design

The official schematic sheet (v2.0) is embedded below. Click on the preview image to open or download the vector PDF:

_{🔍 Click on the schematic preview above to view or download the vector PDF (Schematics-2.0.pdf)}

2.1 Schematic Subsystem Breakdown

1. Dedicated 3.3V Low-Dropout Regulator (LM1117MP-3.3)

• Design Rationale: The Arduino Nano's internal 3.3V rail (derived from the USB-UART bridge) is limited to $\sim 50,\text{mA}$, whereas the nRF24L01+ PA+LNA transceiver demands peak burst currents upwards of $115\text{--}150,\text{mA}$ during active reception/amplification. Attempting to power the module from the Nano causes severe rail sagging, brownouts, and packet drops.
• Implementation: A dedicated LM1117MP-3.3 SOT-223 LDO regulator (U2) steps down the 5V USB bus rail to an isolated, high-current 3.3V plane (rated up to $800,\text{mA}$).
• Filtering & Decoupling: Implemented according to the manufacturer datasheet with a $10,\mu\text{F}$ input capacitor (C5) and a $10,\mu\text{F}$ output capacitor (C4) ensuring ripple $< 30,\text{mV}_{p-p}$.

2. nRF24L01+ PA+LNA Transceiver Front-End (U1)

• Design Rationale: In previous seasons (FSA 2026 & FSS 2026), telemetry link dropouts occurred around large track perimeters due to insufficient link margin and strong inverter EMI. Using a dedicated external module with integrated Power Amplifier (PA) and Low-Noise Amplifier (LNA) boosts receiver sensitivity down to $-95,\text{dBm}$ (@ $250,\text{kbps}$) and transmit power to $+20,\text{dBm}$.
• Antenna Interface: Standard SMA Female edge connector ($50,\Omega$) matched for external high-gain 2.4 GHz whip antennas elevated outside the pit enclosure.
• Local Decoupling: Additional $1,\mu\text{F}$ (C1) and $10,\text{nF}$ (C2) ceramic capacitors placed directly across $V_{CC}$ and $GND$ pins.
• Testability: Dedicated testpoint TP1 (nrf_power_tp) allows direct DMM/oscilloscope measurement of the transceiver power rail.

3. Processing Unit & USB Interface (A1)

• Core Microcontroller: Arduino Nano 3.0 module footprint featuring native USB-C connectivity and the ATmega328P (16 MHz, 5V logic).
• Decoupling: $100,\text{nF}$ capacitor (C3) tied from AREF to GND to suppress high-frequency analog reference noise.
• RF-NANO Pin Mapping Alignment: Control and SPI signal lines follow the industry-standard RF-NANO mapping to ensure cross-compatibility with firmware sketches.

4. Diagnostic & Radio Status LED Indicators

• Comm_status_indicator (D1 LED + $2,\text{k}\Omega$ R1): Connected to Arduino digital pin D2. Controlled via software to blink during active packet reception or remain steady when the RF link is healthy.
• nRF24_detected (D2 LED + $2,\text{k}\Omega$ R2): Connected to Arduino digital pin D3. Illuminates automatically on setup if radio.isChipConnected() succeeds, providing instantaneous visual feedback isolating socket/transceiver hardware faults from software issues.

3. PCB Layout & Physical Implementation

3.1 Routing Strategy & Layer Stackup

• Component Placement:
  • Arduino Nano 3.0 socket on the left half with USB-C facing outward for unobstructed chassis cable insertion.
  • nRF24L01+ PA+LNA header socket on the right half with antenna port facing outward.
  • LM1117MP-3.3 regulator and decoupling capacitor cluster (C1–C5) tightly positioned directly below the transceiver header to minimize inductive trace loops.
  • Status LEDs (D1, D2) and current-limiting resistors (R1, R2) placed along the top edge for direct visibility.
• Power Distribution: Wide copper traces for the +5V bus and 3.3V output rail, combined with an unbroken ground plane on the bottom layer to ensure low-impedance RF return paths.
• Mechanical Mounting: Four symmetric M3 mounting holes (3.2 mm drill diameter) placed at the corners, dimensioned for M3 threaded heat-set inserts in a custom 3D-printed enclosure.

4. Pinout & Hardware Interfacing

[!IMPORTANT] Authoritative Pinout Notice:
The pinout below is the definitive, verified hardware mapping matching Schematics-2.0.pdf and the board layout.

• CE (Chip Enable): D7 (ATmega328P PD7 / Pin 11)
• CSN (Chip Select Not): D8 (ATmega328P PB0 / Pin 12)
• Comm_status_indicator: D2 (PD2 / Pin 5)
• nRF24_detected: D3 (PD3 / Pin 6)
• SPI Bus: MOSI $\rightarrow$ D11, MISO $\rightarrow$ D12, SCK $\rightarrow$ D13

4.1 Pinout & Complete Circuit Interconnection Table

4.2 Production Receiver Firmware (SW/RTT_nano_26/)

The official receiver firmware sketch is located in SW/RTT_nano_26/RTT_nano_26.ino.

Pinout Migration from Legacy Prototypes:

#include <SPI.h>
#include <RF24.h>
#include "printf.h"

// Hardware Pin Configuration (IFS09-TeleReceiver)
static const uint8_t PIN_CE           = 7;  // D7 -> nRF24 CE
static const uint8_t PIN_CSN          = 8;  // D8 -> nRF24 CSN
static const uint8_t PIN_LED_COMM     = 2;  // D2 -> Comm Status LED
static const uint8_t PIN_LED_DETECTED = 3;  // D3 -> nRF24 Detected LED

RF24 radio(PIN_CE, PIN_CSN);

void setup() {
    pinMode(PIN_LED_COMM, OUTPUT);
    pinMode(PIN_LED_DETECTED, OUTPUT);
    Serial.begin(115200);

    if (radio.begin() && radio.isChipConnected()) {
        digitalWrite(PIN_LED_DETECTED, HIGH); // Visual confirmation of SPI detection
        
        radio.setAddressWidth(5);
        radio.setChannel(76);
        radio.setAutoAck(false);
        radio.setDataRate(RF24_1MBPS);

5. Formal Design Documents & Reports

The project development is documented across three primary engineering artifacts:

6. Repository Structure

IFS09-TE-TeleReceiver/
├── docs/                              # Documentation Assets
│   └── images/
│       ├── schematic_v2.png           # Exported Schematic v2.0 Image
│       ├── pcb_layout_2d.png          # 2D PCB Layout Routing View
│       ├── pcb_render_3d.png          # 3D PCB Render Model
│       └── rf_nano_pinout.png         # Definitive Pinout Reference
├── IFS09-TeleReceiver/                # KiCad Project Files (KiCad E.D.A. 10.x / 8.x)
│   ├── IFS09-TeleReceiver.kicad_pro   # Project Configuration
│   ├── IFS09-TeleReceiver.kicad_sch   # Schematic Sheet
│   └── IFS09-TeleReceiver.kicad_pcb   # PCB Layout & Netlist
├── SW/                                # Firmware Sketches & Libraries
│   └── RTT_nano_26/                   # Production Telemetry Receiver Firmware
│       ├── RTT_nano_26.ino            # Main Arduino Receiver Sketch
│       └── printf.h                   # Serial Printf Header
├── DR_TE-IFS09-TeleReceiver.pdf       # Official Design Report (Rev 1)
├── WO_TE-IFS09-TeleReceiver.pdf       # Work Order Specification (Rev 1)
├── Schematics-2.0.pdf                 # Latest Exported Schematic Sheet (v2.0)
├── Schematics-1.0.pdf                 # Initial Schematic Sheet (v1.0)
├── .gitignore                         # KiCad and OS ignore rules
└── README.md                          # Comprehensive Documentation

7. Validation & Testing Protocol (Post-Fabrication)

Upon arrival of manufactured PCB units, the following sequential validation protocol will be executed prior to track deployment:

flowchart LR
    A[1. Power Rail Check (TP1)] --> B[2. SPI & Detection (LED D2)]
    B --> C[3. PuTTY Stream (115200)]
    C --> D[4. Dynamic Range Test (≥300m)]

1. Power Supply Rail Verification:
   • Unpowered continuity check across TP_5V $\rightarrow$ GND and TP1 (3V3) $\rightarrow$ GND ($> 10,\text{k}\Omega$).
   • Connect USB-C: Verify $5.00,\text{V} \pm 0.25,\text{V}$ input and $3.30,\text{V} \pm 0.10,\text{V}$ output on TP1 with peak ripple $< 30,\text{mV}_{p-p}$.
2. Microcontroller to Transceiver Interface Test:
   • Flash receiver test sketch. Verify radio.isChipConnected() == true and illumination of nRF24_detected LED (D3).
   • Probe SCK, MOSI, MISO, CSN, and CE testpoints with logic analyzer/oscilloscope.
3. USB-Serial Communication Test (PuTTY):
   • Connect to ground station PC at 115200 baud (8-N-1, No Flow Control).
   • Stream mock telemetry frames continuously for 10 minutes with 0% framing errors or data dropouts.
4. Vehicle Dynamic Range & Link Budget Test:
   • Mount transmitter in car; place base station in pits with external 2.4 GHz whip antenna.
   • Verify Packet Reception Rate ($\text{PRR} \ge 95%$) over the full track perimeter ($\ge 300,\text{m}$ line of sight).

8. Author & Team Credits

• Subsystem: Telemetry Subsystem (TE)
• Author & Technical Director: Andrés Sánchez de Ágreda
• Team: ISC Formula Student Racing Team — Universidad Pontificia Comillas (ICAI)
• Season: 2026 / 2027

ISC Racing Team — IFS09 Telemetry Subsystem