# HTIT-Tracker V0.5 Schematic

## Document Metadata
- **Format:** PDF 1.4
- **Title:** New Output
- **Keywords:** Altium
- **Creator:** Altium Designer
- **Producer:** llPDFLib 3.x
- **Creation Date:** 2023-07-31

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## Schematic Components

This is the full schematic for the Heltec Wireless Tracker V0.5, designed in Altium Designer.

### Power Management

| Component | Value/Part | Function |
|-----------|-----------|----------|
| F1 | 6V 500mA | Fuse |
| D1 | RSB6.8S | TVS Diode |
| D2 | 1N5819 | Schottky Diode |
| Q1 | AO3401 | P-channel MOSFET |
| U2 | TP4054 | LiPo Charger IC |
| U4 | CE6260B33M | 3.3V LDO |
| U6 | CE6260B33M | 3.3V LDO (Vext) |
| R16 | 2K/5% | Charge current set |

### ESP32-S3FN8 Main MCU (U7)

**Crystal:**
| Component | Value |
|-----------|-------|
| U5 | 40MHz Crystal |
| C19, C20 | 22pF/10V |
| X1 | 32.768KHz (RTC) |
| C8, C22 | 4.7pF/10V |

**Key GPIO Connections:**
- GPIO0: USER_Key
- GPIO1: Vbat_Read (via ADC)
- GPIO2: ADC_Ctrl
- GPIO3: Vext_Ctrl
- GPIO8: LoRa_NSS
- GPIO9: LoRa_SCK
- GPIO10: LoRa_MOSI
- GPIO11: LoRa_MISO
- GPIO12: LoRa_RST
- GPIO13: LoRa_BUSY
- GPIO14: DIO1
- GPIO18: LED Write Ctrl
- GPIO19/20: USB_D-/USB_D+
- GPIO21: LED_K (TFT backlight)
- GPIO33: GNSS_TX
- GPIO34: GNSS_RX
- GPIO35: GNSS_RST
- GPIO36: GNSS_PPS
- GPIO38-42: TFT Display (CS, RES, RS, SCLK, SDIN)
- GPIO47: BOOT_MODE
- GPIO48: D_SEL

### SX1262 LoRa Module (U12)

| Component | Value | Function |
|-----------|-------|----------|
| L1 | 2.7nH | RF matching |
| L2 | 24nH | RF filter |
| L3 | 2.0nH | RF matching |
| C12, C15, C18, C25 | 0.1uF | Decoupling |
| C13, C14 | 1.8pF | RF matching |
| U11 | UPG2179 | RF Switch |
| X4 | 32MHz | TCXO |
| E4 | IPEX | LoRa Antenna |

### UC6580 GNSS Module (U9)

| Component | Value | Function |
|-----------|-------|----------|
| X2 | 26MHz | TCXO |
| X3 | 32.768KHz | RTC Crystal |
| C34, C41 | 4.7pF | Crystal load |
| R27 | 10K/5% | Reset pullup |
| U8 | HDDL1L5RSS-B8 | L1/L5 LNA |
| U10 | SW7125DE | RF Amplifier |
| E3 | IPEX | GNSS Antenna |

**RF Frontend:**
| Component | Value |
|-----------|-------|
| L4 | 68nH |
| L5 | 1nH |
| L6 | 2.2nH |
| L7 | 18nH |
| L8 | 0R/5% |
| L9 | 6.8nH |
| L10 | 7nH |
| L11 | 4.5nH |
| EL2 | 1uH (inductor) |

### TFT Display (U1 - 0.96" OLED)

| Pin | Signal |
|-----|--------|
| SDIN | GPIO42 |
| SCLK | GPIO41 |
| RS | GPIO40 |
| RES | GPIO39 |
| CS | GPIO38 |
| LED_K | GPIO21 (via Q4) |

### USB Type-C (U3)

| Pin | Signal |
|-----|--------|
| VBUS | VDD_5V |
| DN1/DN2 | USB_N |
| DP1/DP2 | USB_P |
| CC1 | R3 (5.1K to GND) |
| CC2 | R6 (5.1K to GND) |

### Battery Management

| Component | Value | Function |
|-----------|-------|----------|
| JP3 | 1.25X2P-LiPo | Battery connector |
| C1 | 10uF/10V | Input cap |
| C2 | 220nF/10V | Charge cap |
| R13 | 390K/1% | Voltage divider |
| R14 | 100K/1% | Voltage divider |
| Q2 | AO3401 | Power switch |
| Q3 | S9013 | ADC control |

### LEDs

| LED | Color | Resistor | Function |
|-----|-------|----------|----------|
| LED1 | Orange | R7 (330R) | Charging indicator |
| LED2 | White | R10 (330R) | User LED |

### Buttons

| Button | Function |
|--------|----------|
| S1 | RESET_SW |
| S2 | USER_SW (GPIO0) |

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## Pin Headers

### Header P2 (8-pin)
Power and ground pins

### Header P3 (8-pin)
Additional GPIO

### Header P4 (16-pin)
Main GPIO header J2

### Header P5 (16-pin)
Main GPIO header J3

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![Schematic Detail](../images/schematic_page_1_img_1.png)