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Hardware Specifications

This page provides comprehensive technical specifications for all hardware components supported by Calculinux.

PicoCalc Hardware

Physical Specifications

Specification Details
Form Factor Pocket-sized handheld computer
Display Built-in 320×320 LCD screen
Input Full physical keyboard with compact layout
Power USB-C port for charging, internal rechargeable battery
Module Interface Custom connector for SBC modules

Display System

Specification Details
Interface SPI (Serial Peripheral Interface)
Controller ILI9488
Resolution 320×320 pixels
Text Mode 53 columns × 40 rows (6×8 font)
Color Depth 16-bit RGB565
Refresh Rate ~30 FPS target (60Hz capable)
SPI Speed 80 MHz (overclocked from 40 MHz standard)
Backlight Controlled by STM32 MCU

Keyboard System

Specification Details
Type Physical matrix keyboard
MCU STM32F103R8T6 (keyboard controller/southbridge)
Interface I2C to main SBC
I2C Address 0x1F
I2C Bus i2c2 at 400kHz
Layout Compact layout with function keys
Features Mouse mode (dual shift), MCU-based matrix scanning

USB-C Ports

The PicoCalc has TWO USB-C ports with different functions:

Port Function Notes
PicoCalc USB-C Port Battery charging + Serial console Console at 1500000 baud, connects to Lyra UART
Lyra USB-C Port USB-OTG data only Does NOT charge PicoCalc, requires 3.3V devices

Two Distinct USB-C Ports

  • PicoCalc port: Accessible externally, charges battery, provides serial console access for debugging
  • Lyra port: Internal (requires case opening), USB host/device functionality, 3.3V only

Power System

Specification Details
Battery Internal rechargeable lithium-ion
Charging Via PicoCalc USB-C port
Input Voltage 5V
Power Consumption (Idle) ~0.5-0.52W
Power Consumption (Active) ~0.59-0.60W
Power Consumption (WiFi) ~0.63-1.1W
Battery Life 2-4 hours typical (varies by usage)

Storage

Type Location Notes
Primary Storage MicroSD in Luckfox Lyra Main system storage
Expansion Storage MicroSD in PicoCalc slot Additional storage via SPI (slower)

Luckfox Lyra Specifications

Processor

Component Specification
SoC Rockchip RK3506G2
CPU Triple-core ARM Cortex-A7 @ 1.2GHz + ARM Cortex-M0
Architecture ARMv7-A (32-bit)
NPU 0.5 TOPS AI accelerator

Memory & Storage

Component Supported Configurations
RAM 128MB DDR2 (only tested configuration)
Flash Storage Optional SPI NAND (128MB-1GB, must be erased for SD boot)
External Storage MicroSD card slot (primary boot device)

RAM Configuration

Only the 128MB RAM configuration has been tested with Calculinux. Other RAM variants (64MB, 256MB) exist but have different pinouts and would require custom adapter boards.

Network Interfaces

Interface Availability Notes
WiFi External USB adapter required See supported chipsets below
Ethernet Lyra Plus model only 10/100 Mbps, untested with Calculinux
Bluetooth Not supported No Bluetooth hardware

Expansion Interfaces

All interfaces operate at 3.3V logic levels:

Interface Status Notes
GPIO ✅ Available External GPIO free (display/keyboard don't use)
USB ✅ Available Internal USB host/device, 3.3V only
I2C ✅ Available Multiple I2C buses
I2S ❓ Untested Audio interface available
SPI ✅ Available Shared with display
UART ✅ Available Serial communication
MIPI DSI 🚧 Possible For alternate displays (22-pin CM4 connector)

Critical: 3.3V Logic Levels

ALL interfaces operate at 3.3V ONLY. Using 5V devices or signals will damage the hardware. Always verify voltage compatibility before connecting peripherals.

Display Interface Details

Parameter Value
SPI Bus spi0
SPI Mode 0 (CPOL=0, CPHA=0)
Max Speed 80 MHz
Chip Select GPIO0 RK_PA4
Data/Command GPIO0 RK_PA3
Reset GPIO0 RK_PA2

Keyboard Interface Details

Parameter Value
Interface I2C
Bus i2c2
Address 0x1F
Speed 400 kHz (Fast Mode)
SCL Pin GPIO0 RK_PB2
SDA Pin GPIO0 RK_PB3

Supported WiFi Chipsets

The following USB WiFi adapters are supported (must operate at 3.3V):

Enabled in Current Kernel

  • RTL8192CU - Realtek single-band USB adapter
  • R8712U - Realtek single-band USB adapter
  • R8188EU - Realtek single-band USB adapter
  • RTL8723BS - Realtek dual-band (SDIO/USB)

Requiring Kernel Configuration

The following chipsets have drivers available but are not currently enabled:

  • RTL8723DU
  • RTL8812AU
  • RTL8814AU
  • RTL8821CU
  • RTL88X2BU
  • RTL8188FU
  • RTL8188FTV
  • RT2800 series
  • MT7612U
  • MT7610U
  • RT5370

3.3V Requirement for WiFi

USB WiFi adapters must operate at 3.3V as the Lyra's USB provides only 3.3V power. Standard 5V USB adapters will not work and may damage the board. Use an externally powered USB hub for 5V devices.

Boot Priority

The RK3506G2 boot ROM follows this priority:

  1. SPI NAND (if present and programmed)
  2. SD Card (if SPI NAND is erased or absent)
  3. USB Boot (for recovery/programming)

SPI NAND Boot Priority

If your Luckfox Lyra has SPI NAND flash, you must erase it or the boot ROM will ignore the SD card. See the SPI NAND Erase Guide for detailed instructions.

Luckfox Lyra Variants

Model RAM Storage Ethernet Status with Calculinux
Luckfox Lyra 128MB SD only No ✅ Fully Supported
Luckfox Lyra (SPI NAND) 128MB SPI NAND + SD No ✅ Supported (NAND must be erased)
Luckfox Lyra Plus 128MB SPI NAND + SD Yes (10/100) ❓ Untested

Other Lyra Models

Other Luckfox Lyra variants exist (64MB, 256MB RAM, different SoC models) but have different pinouts and are not compatible without custom adapter boards.

Thermal Considerations

Condition Details
Normal Operation No heatsink required for typical console use
Heavy Load Monitor temperatures during intensive tasks
Enclosed Design PicoCalc case limits airflow, consider heat dissipation

Power Supply Requirements

Component Requirement
Input Voltage 5V DC
Minimum Current 2A
Recommended 5V 2A or higher USB power supply
Cable USB-C data-capable cable

Power Supply Recommendations

  • Use a quality USB-C cable (not just charging cables)
  • Ensure power supply can deliver stable 2A
  • Under-voltage can cause system instability and boot failures
  • Quality power supplies reduce risk of data corruption

Console Display Specifications

Parameter Value
Physical Resolution 320×320 pixels
Console Font 6×8 pixels per character
Text Area 53 columns × 40 rows
Color Support 16-bit color (RGB565)
Frame Rate 30 FPS target

Small Text Console

The 53×40 text area is smaller than standard terminals (typically 80×24 or larger). Many applications may require:

  • Horizontal scrolling for wide output
  • Setting COLUMNS=53 LINES=40 environment variables
  • Using compact display modes when available

Note: This page is the canonical reference for all hardware specifications. Other pages should link here rather than duplicating these details.