Hardware Guide

Complete hardware configuration and pin mapping for SerialyTTY.

ESP32-C6 DevKit

Board Specifications

Specification	Value
MCU	ESP32-C6-WROOM-1
Architecture	RISC-V 32-bit
CPU Frequency	160 MHz
RAM	320 KB SRAM
Flash	8 MB
WiFi	802.11 b/g/n (2.4 GHz)
Bluetooth	BLE 5.0
USB	USB 2.0 Full Speed (native)
Operating Voltage	3.3V

Power Requirements

• Input Voltage: 5V via USB-C
• Operating Current: ~100mA (typical), up to 500mA with peripherals
• Deep Sleep: <10µA (when implemented)

Pin Configuration

UART Bridge (Primary Function)

Function	GPIO	Description
UART1_RX	GPIO16	Receives data from target device
UART1_TX	GPIO17	Transmits data to target device
UART0_RX	GPIO20	USB Serial (console)
UART0_TX	GPIO21	USB Serial (console)

UART Configuration:

• Baud Rate: Auto-detected (9600-115200)
• Data Bits: 8
• Parity: None
• Stop Bits: 1
• Flow Control: None

TFT Display (ILI9341) - Optional

Function	GPIO	Description
SPI_MOSI	GPIO7	Master Out Slave In (shared)
SPI_MISO	GPIO2	Master In Slave Out (shared)
SPI_SCLK	GPIO6	SPI Clock (shared)
TFT_CS	GPIO10	Chip Select (Display)
TFT_DC	GPIO3	Data/Command
TFT_RST	GPIO4	Reset
TFT_BL	GPIO5	Backlight Control

SPI Configuration:

• Clock Speed: 40 MHz
• Mode: SPI Mode 0
• Bit Order: MSB First
• DMA: Channel 1 (enabled)

Display Specifications:

• Resolution: 240x320 pixels
• Color Depth: RGB565 (16-bit)
• Interface: 4-wire SPI
• Operating Voltage: 3.3V
• Backlight: PWM controlled (future)

SD Card Module - Optional

Function	GPIO	Description
SPI_MOSI	GPIO7	Master Out Slave In (shared)
SPI_MISO	GPIO2	Master In Slave Out (shared)
SPI_SCLK	GPIO6	SPI Clock (shared)
SD_CS	GPIO1	Chip Select (SD Card)

SPI Configuration:

• Clock Speed: 20 MHz (default), up to 40 MHz
• Mode: SPI Mode 0
• Filesystem: FAT16/FAT32
• Voltage: 3.3V (ensure card is 3.3V compatible!)

SD Card Requirements:

• Type: microSD or SD (with adapter)
• Format: FAT32 (recommended)
• Capacity: Up to 32GB tested
• Speed Class: Class 4 or higher

I2C Bus (Reserved)

Function	GPIO	Description
I2C_SDA	GPIO8	I2C Data (future expansion)
I2C_SCL	GPIO9	I2C Clock (future expansion)

I2C Configuration:

• Speed: 100 kHz (standard mode)
• Address Range: 0x08-0x77
• Pull-ups: 4.7kΩ external required

Available GPIO Pins

Reserved for future expansion:

GPIO	Current Use	Notes
GPIO0	Free	Boot mode control (avoid external pull-down)
GPIO11	Free	General purpose
GPIO12	Free	General purpose
GPIO13	Free	General purpose
GPIO18	Free	General purpose
GPIO19	Free	General purpose
GPIO22	Free	General purpose
GPIO23	Free	General purpose

Wiring Diagrams

Minimal Configuration (UART Only)

ESP32-C6                Target Device
┌─────────┐            ┌─────────┐
│         │            │         │
│  GPIO16 │◄───────────│   TX    │
│  (RX)   │            │         │
│         │            │         │
│  GPIO17 │────────────►   RX    │
│  (TX)   │            │         │
│         │            │         │
│   GND   │────────────│   GND   │
│         │            │         │
└─────────┘            └─────────┘

Full Configuration (with Display and SD)

                  ┌─────────────────┐
                  │   ESP32-C6      │
                  │                 │
    ILI9341       │  GPIO7 (MOSI)   │──┬── SD Card MOSI
    MOSI ─────────│  GPIO2 (MISO)   │──┤
    MISO ─────────│  GPIO6 (SCLK)   │──┴── SD Card SCLK/MISO
    SCLK ─────────│  GPIO10 (CS)    │
    CS   ─────────│  GPIO3  (DC)    │      SD Card
    DC   ─────────│  GPIO4  (RST)   │      CS ────── GPIO1
    RST  ─────────│  GPIO5  (BL)    │
    BL   ─────────│                 │
                  │  GPIO16 (RX)    │──── Target TX
                  │  GPIO17 (TX)    │──── Target RX
                  │                 │
                  │   GND           │──── Common Ground
                  │   3.3V          │──── Power peripherals
                  └─────────────────┘

Hardware Setup Instructions

Step 1: ESP32-C6 Preparation

1. Inspect the board for physical damage
2. Verify all GPIO pins are accessible
3. Connect USB-C cable to computer
4. Confirm device enumeration (check device manager/dmesg)

Step 2: TFT Display Connection (Optional)

1. Verify display voltage: Must be 3.3V compatible
2. Connect power first: VCC to 3.3V, GND to GND
3. Connect SPI bus: MOSI, MISO, SCLK (shared with SD)
4. Connect control pins: CS, DC, RST, BL

Important:

• Use short, twisted-pair wires for SPI signals
• Keep SPI traces under 10cm if possible
• Add 0.1µF decoupling capacitor near display VCC

Step 3: SD Card Connection (Optional)

1. Format SD card: FAT32 using computer
2. Verify voltage: Use 3.3V compatible module only
3. Connect SPI bus: Share MOSI, MISO, SCLK with display
4. Connect CS: GPIO1 (different from display CS)

Important:

• Many SD modules have built-in level shifters - check specs
• Ensure separate chip select (CS) pins
• Test SD card reads/writes on computer first

Step 4: Target Device Connection

1. Identify target UART pins (TX, RX, GND)
2. Cross-connect: Target TX → ESP32 RX (GPIO16)
3. Cross-connect: Target RX → ESP32 TX (GPIO17)
4. Common ground: Connect GND pins

Warning: Ensure voltage levels match (3.3V). Use level shifters for 5V devices.

Signal Quality Considerations

SPI Bus Sharing

The display and SD card share the SPI bus (MOSI, MISO, SCLK) but have separate chip select (CS) pins:

• Display CS: GPIO10
• SD Card CS: GPIO1

Best Practices:

• Only one device active at a time (enforced in software)
• Use pull-up resistors on CS lines (10kΩ recommended)
• Minimize capacitive loading with short wires

UART Signal Integrity

For reliable baud detection:

• Use twisted-pair or shielded cable for long runs
• Keep UART traces away from SPI clock
• Add series termination (22-47Ω) for high speeds
• Avoid running UART parallel to power lines

Power Distribution

• Add bulk capacitor (100µF) near ESP32-C6 power input
• Add ceramic capacitor (0.1µF) near each peripheral
• Keep power traces wide (>20 mil) and short
• Monitor voltage drop - should stay within ±5%

Testing Hardware Connections

Visual Inspection Checklist

• All connections secure and properly seated
• No short circuits between adjacent pins
• Polarity correct (VCC, GND)
• Signal lines match pin configuration

Power-On Test

1. Connect USB cable (no peripherals)
2. Verify green LED on ESP32-C6 board
3. Check device appears in serial port list
4. Measure 3.3V between VCC and GND pins

Peripheral Test

1. Display: Should show boot screen on power-up (if enabled)
2. SD Card: Check for mount success message in serial log
3. UART: Loopback test - connect GPIO16 to GPIO17, verify echo

Troubleshooting Hardware Issues

Display Issues

Symptom	Possible Cause	Solution
Blank/white screen	Power issue	Check VCC/GND, measure voltage
Garbled display	SPI timing	Reduce SPI clock speed
No response	CS/DC/RST wrong	Verify pin connections
Dim display	Backlight off	Check BL pin (GPIO5)

SD Card Issues

Symptom	Possible Cause	Solution
Mount fails	Format incompatible	Reformat as FAT32
Read errors	Bad card	Try different SD card
No detection	CS not working	Verify GPIO1 connection
Slow performance	Low speed card	Use Class 10 card

UART Issues

Symptom	Possible Cause	Solution
No data received	TX/RX swapped	Cross-check connections
Corrupted data	Baud mismatch	Run auto-detection
Intermittent errors	Signal quality	Shorten cables, add pull-ups
No communication	Voltage mismatch	Check 3.3V/5V levels

PCB Design Guidelines (Future)

For custom PCB integration:

1. Layer Stack: Minimum 2-layer, 4-layer recommended
2. SPI Routing: Match length within 10mm, 50Ω impedance
3. UART Routing: Differential pairs if possible, 90Ω impedance
4. Ground Plane: Solid ground pour on bottom layer
5. Decoupling: 0.1µF ceramic caps within 5mm of ICs
6. Test Points: Add TP on all critical signals

---

Next: Learn about Features and system capabilities.