Serial Terminal Apps
Serial terminal applications for ASIC miner debugging. UART communication tools for control board diagnostics, firmware recovery, and low-level troubleshooting.
Overview
Serial terminal applications let you communicate with a miner's control board via UART (Universal Asynchronous Receiver/Transmitter). This is essential for low-level debugging, viewing boot logs, accessing the bootloader, and recovering bricked devices that can't be reached over the network.
When do you need a serial terminal? When a miner won't boot, has no network connectivity, or you need to access the U-Boot bootloader for NAND recovery. Most routine maintenance doesn't require serial access.
Hardware Requirements
Before using any serial terminal software, you need:
| Item | Description |
|---|---|
| USB-to-UART adapter | CP2102, CH340, FT232, or PL2303 based |
| Jumper wires | Female-to-female Dupont wires |
| Pin header | Solder to control board UART pads if needed |
UART Connection Settings
Most Antminer and Whatsminer control boards use:
| Parameter | Value |
|---|---|
| Baud rate | 115200 |
| Data bits | 8 |
| Stop bits | 1 |
| Parity | None |
| Flow control | None |
Pinout
Connect your USB-to-UART adapter to the control board's UART header:
| Adapter Pin | Control Board Pin |
|---|---|
| TX | RX |
| RX | TX |
| GND | GND |
| Do NOT connect VCC | — |
Never connect the VCC/3.3V line from your USB adapter to the control board. The control board has its own power supply. Connecting VCC can damage both devices.
Serial Terminal Software
PuTTY (Windows)
The classic terminal emulator with serial port support.
PuTTY
v0.81Free SSH, Telnet, and serial terminal client for Windows. Lightweight and reliable for UART debugging.
Configuration:
- Set Connection type to Serial
- Enter your COM port (e.g.,
COM3) — check Device Manager - Set Speed to
115200 - Click Open
Tera Term (Windows)
Feature-rich terminal emulator with macro support and logging.
Tera Term
v5.2Open-source terminal emulator for Windows. Supports serial, SSH, and Telnet with macro scripting and log capture.
CoolTerm (Cross-Platform)
CoolTerm
v2.0.1Simple serial port terminal application. Clean interface with data logging. Works on Windows, macOS, and Linux.
minicom (Linux / macOS)
The standard command-line serial terminal for Unix systems.
# Install
# Ubuntu/Debian
sudo apt install minicom
# macOS
brew install minicom
# Connect (replace /dev/ttyUSB0 with your device)
minicom -b 115200 -D /dev/ttyUSB0
# Or use screen
screen /dev/ttyUSB0 115200picocom (Linux / macOS)
Lightweight alternative to minicom.
# Install
sudo apt install picocom # Debian/Ubuntu
brew install picocom # macOS
# Connect
picocom -b 115200 /dev/ttyUSB0
# Exit: Ctrl+A then Ctrl+XArduino Serial Monitor
If you already have the Arduino IDE installed, its built-in Serial Monitor works well for basic UART communication.
USB-to-UART Driver Installation
Most USB-to-UART adapters require drivers:
| Chip | Driver Source |
|---|---|
| CP2102 / CP2104 | Silicon Labs |
| CH340 / CH341 | WCH |
| FT232 / FT2232 | FTDI |
| PL2303 | Prolific |
macOS users: Recent macOS versions include drivers for most common adapters (CP210x, FTDI). If your adapter isn't detected, install the manufacturer's driver and reboot.
Common UART Debugging Tasks
Viewing Boot Logs
Connect the serial terminal before powering on the miner to capture the full boot sequence:
U-Boot 2016.11 (Feb 10 2023 - 15:30:22 +0800)
DRAM: 512 MiB
MMC: mmc0@10100000: 0
Loading Environment from NAND...
...
Starting kernel ...Accessing U-Boot
To interrupt the boot process and access the U-Boot bootloader:
- Connect serial terminal
- Power on the miner
- Immediately press any key when you see
"Hit any key to stop autoboot" - You now have access to U-Boot commands
# U-Boot commands
printenv # Show environment variables
setenv ipaddr 192.168.1.100 # Set IP
tftpboot 0x82000000 firmware.img # TFTP boot
nand erase.chip # Erase NAND (DANGEROUS)
reset # RebootU-Boot is powerful and dangerous. Commands like nand erase.chip will destroy all data on the control board. Only use U-Boot commands if you understand what they do and have a recovery plan.
Kernel Debugging
After boot, the serial console provides access to the Linux shell:
# Login (credentials vary by model/firmware)
# Common defaults: root/root or root/admin
# View kernel messages
dmesg | tail -100
# Check running services
ps aux | grep cgminer
# View system log
cat /var/log/messagesTroubleshooting Serial Connections
| Problem | Cause | Solution |
|---|---|---|
| No output at all | Wrong baud rate | Verify 115200 bps |
| Garbled text | TX/RX swapped | Swap TX and RX wires |
| COM port not found | Missing driver | Install correct USB-UART driver |
| Partial output | Loose connection | Check wire connections |
| Permission denied (Linux) | User not in dialout group | sudo usermod -aG dialout $USER |
Related Resources
- Diagnostic Software — network scanners and monitoring
- Flash Tools — firmware flashing utilities
- UART, SPI & I2C Protocols — learn about serial communication
- Control Board Architecture
Flash Tools
Firmware flashing tools for ASIC mining hardware. SD card imaging, NAND re-programming, and recovery tools for Antminer, Whatsminer, and Avalon.
Antminer Schematics
Antminer hashboard and control board schematics. Circuit diagrams, block diagrams, and pinout references for Bitmain mining hardware.