Lierda Cat.1 NT26FxDx OpenKit Application Guide_Rev0.1

Chinese

ChangeList

[!NOTE] Note Please remove the enclosure and check the silkscreen model and version on the main board to confirm that your development board version matches this application guide.

NT26FxDx OpenKit is an embedded development kit based on a Cat.1 communication module for rapid evaluation and development with Lierda’s NT26F series OpenCPU SDK. The kit integrates cellular networking, voice interaction, a camera, touch screen, LCD display, and peripheral expansion, helping customers quickly become familiar with module capabilities and carry out application validation.

The development board includes an NT26FxDx module, onboard ES8311 audio codec, Class-AB/Class-D power amplifier, camera interface, and LCD/dot-matrix display interfaces, while also integrating lithium battery charging management and multiple regulated power supply circuits. Based on this kit, users can implement network communication, voice capture and playback, screen display, image acquisition, and other functions. It is suitable for prototype development and functional validation in scenarios such as smart terminals, voice interaction, image acquisition, and IoT devices.

This application guide will help you get started quickly with NT26FxDx OpenKit and provide detailed information about this development board.

TBD

This guide includes the following content:

• Hardware Version: Introduces hardware revision history and known issues.

• Getting Started: Briefly introduces the development board and provides hardware and software setup guidance.

• Hardware Reference: Provides detailed hardware information for the development board.

• Related Resources: Lists links to related documents.

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Hardware Version

This document applies only to the NT26FxDx OpenKit main board model: L-CT4IT00-YP00W-01_V04.

PCB Model	PCB Version	Change Log
L-CT4IT00-YP00W-01	V04	/

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Getting Started

This section briefly introduces NT26FxDx OpenKit and explains how to flash firmware onto NT26FxDx OpenKit and prepare the required environment.

Component Introduction

Component Model	Description
L-CT4IT00-YP00W-01_V04	Main Board PCB
24031C12	LCD+TP
ZJY096I0400WG01	OLED
TBD	Battery
TBD	Enclosure
TBD	Camera
TBD	LCD ADP PCB
TBD	Speaker
TBD	Antenna

L-CT4IT00-YP00W-01_V04 (Main Board PCB)

24031C12 (LCD+TP)

ZJY096I0400WG01 (OLED)

TBD (Enclosure)

TBD (Battery)

TBD (Camera)

TBD (LCD ADP PCB)

TBD (Speaker)

TBD (Antenna)

Main Board Introduction

The main components and interfaces of NT26FxDx OpenKit are described below:

Main Components (TOP)	Description
Pwrkey Button	Pwrkey, used to power the module on and off
USB Connector*(1)*	Type-C connector for power supply, charging, communication, and download
Charging Indicator	Two indicators, red and green. The red light stays on while charging, and the green light stays on when fully charged
Reset Button	Reset, used to reset the module
CL4056D	Charging management chip, suitable for 4.2V batteries
Antenna Socket	IPEX Gen-1 socket
RGB LED	RGB indicator, indicates module operating status
Onboard Silicon MIC	Either this or the microphone connector can be used
Microphone Connector*(2)*	1.25mm/2PIN connector socket for connecting an electret microphone
Boot Button	Used to force entry into download mode
NT26F6D0 Module	Cat.1 bis module supporting OPEN application development
Dot-Matrix Display Connector	Used to connect an SSD1306 dot-matrix display (12864/12832)
Key0/1/2 Buttons	Three user-defined buttons
Main Components (BOT)	Description
Camera Connector*(3)*	0.5mm/24PIN FPC connector for connecting a camera module
ES8311	High-performance audio codec chip
LDO28	2.8V/300mA low-dropout linear regulator
Nor flash	Nor flash chip, 32Mbit, suitable for 3.3V systems
SIM Card Slot	Nano-SIM card slot connector for inserting a SIM card
CST8302A	Class-AB/Class-D amplifier
LDO33	3.3V/300mA low-dropout linear regulator
Speaker Connector	1.5mm/2PIN connector socket for connecting a 4 ohm/3W speaker
LCD Connector*(4)*	0.5mm/20PIN FPC connector for connecting the display adapter board
Battery Connector*(5)*	1.5mm/3PIN connector socket

[!NOTE] Note

1. USB Connector: Use a USB 2.0 cable with D+/D- data lines, not a charge-only cable.

2. Microphone Connector: This interface is polarized. Pay attention to the positive and negative wire order when connecting it, or recording will not work.

3. Camera Connector: The FPC connector is a top-contact type, so the exposed contacts on the flex cable must face downward during insertion.

4. LCD Connector: The connector supports contact on both sides. Check the pin order carefully when inserting the flex cable to prevent reverse insertion.

5. Battery Connector: Be sure to verify that the battery terminal wire order, such as positive, negative, and NTC, matches the board-side connector definition. Incorrect wiring may damage the device.

Enclosure Interfaces

Key enclosure interfaces are described below: TBD

Start Using

Visually inspect the product before power-on to ensure the appearance is intact and there is no obvious damage.

Required Hardware

• NT26FxDx OpenKit complete unit

• Type-C data cable*

• Computer (Windows, Linux, or macOS)

[!NOTE] Note Some USB data cables support only power supply and charging and cannot be used for communication or download. Make sure the USB data cable you use supports firmware download.

Powering On the Hardware

A USB data cable is required for power supply, communication, and flashing. Connect the PC and NT26FxDx OpenKit with a USB data cable, then press and hold the power button for more than 3 seconds.

Driver Installation

For driver installation, refer to Lierda EigenComm Cat.1 bis Module USB Driver Installation Guide. After installation, the Lierda USB port can be seen in Device Manager.

Indicator Lights

NT26FxDx OpenKit indicates charging and operating status through the charging indicator and RGB indicator.

Charging Indicator

• When USB is not connected, the charging indicator is off

• When USB is connected, the charging indicator is red, indicating normal charging

• When USB is connected, the charging indicator is green, indicating the battery is fully charged

RGB Indicator

• When powered off, the RGB indicator is off

• When powered on, the RGB indicator stays solid green during normal operation

• When powered on, the RGB indicator flashes blue during voice interaction

• When powered on, the RGB indicator stays solid red in an abnormal state, such as network failure

• When powered on, the RGB indicator flashes green three times before shutdown

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Hardware Reference

Functional Block Diagram

The functional block diagram of NT26FxDx OpenKit is shown below.

Power Supply Methods

The main board includes a power switching circuit, and the system can be powered in the following ways:

1. Powered by Battery The device integrates a 3.7V lithium battery internally. Press the power button for 3 seconds to power it on.

2. Powered by Type-C Port Insert a Type-C USB data cable into the USB interface. The system power automatically switches to Type-C power supply. If the Charge_DET function is enabled, the device can power on when USB is inserted. If the Charge_DET function is not enabled, press the power button for 3 seconds to power it on.

Charging Circuit

The maximum charging voltage of CL4056D is 4.2V. For NTC, a battery with `R25=100K ohm` and `B25/50=4250` is recommended. With a `53.6K ohm/920K ohm` design, the charging temperature range can be `0.14 degC to 45.17 degC`. When `R25=10K ohm`, the charging range can be designed as `0 to 50 degC`. As shown in the reference circuit, when paired with a 103040 battery (`R25=10K ohm`, `B25/50=3435`), the charging temperature range is designed as `0.46 degC to 50.22 degC`. For the detailed calculation method, see the table below: [NTC Calculation Tool](images/NT26FxDx%20OpenKit%20Application%20Guide_Rev0.1/NTC_Calculation_Tool_V1.2.xlsx)(XLSX)

USB Interface

The CC1/CC2 pins of the USB Type-C connector are each pulled down to ground through a `5.1k ohm` resistor by default, configuring the device as a power sink and upstream-facing port (UFP) that supports charging only.

SIM Card Interface

In addition to the SIM card slot, the main board also reserves a package footprint for a chip SIM. The two overlap in PCB position, and the pluggable SIM card is used by default and must be provided by the user.

RF Interface

The RF interface reserves an IPEX Gen-1 socket and a pi-type matching network. If the antenna needs to be replaced, the matching can be adjusted.

Button Interface

**The following buttons have special usage:** 1. The basic function of `PWRKEY` is as a power on/off button. After power-on, the press duration can also be adjusted so it can be used as a function button, for example, short press for conversation and long press for shutdown. 2. `KEY_USER0/KEY_USER1` can be multiplexed as wakeup buttons with higher interrupt priority, and can also be multiplexed as `AGPIO` so they retain their state during module sleep.

Dot-Matrix Display Interface

The dot-matrix display interface reserves a `2.54mm/4pin` soldering position and can optionally be used with the `ZJY096I0400WG01` accessory after soldering. Please note that the display power-on sequence must satisfy `3V3 powers on first, then I2C goes high`. Otherwise, an abnormal power-on sequence may randomly cause a black screen and make the display unusable.

LCD Interface

The LCD interface provides two options: `SPI` (single-line) and `QSPI` (four-line). It also supports an optional touch panel and dual-screen setup. **Please note**: Because different displays may have different interface pin orders and interface positions, an adapter board is recommended when debugging displays. NT26FxDx OpenKit provides a `TBD` adapter board model for connecting the `24031C12` display.

When using an SPI display, the following pins are available:

Display Pin Reference	Corresponding Net Name
VCC	3V3
IOVCC	VDD_EXT
TE	LCD_TE
SDA	LCD_D0
DC	LCD_D1
SCL	LCD_CLK
CS	LCD_CS1/LCD_CS2*(1)*
RST	LCD_RST
GND	GND
A	3V3
K	LCD_LED ctrl NPN*(2)*

[!NOTE] Note

1. To debug the dual-screen function, one 0R resistor needs to be soldered at R120 to connect the LCD_CS2 pin. I2C1_SCL and LCD_CS2 cannot be used at the same time, which means the dot-matrix display and touch panel cannot be used together with the dual-screen configuration.

2. LCD_LED controls the backlight cathode as the EN pin. It is recommended to reserve a current-limiting resistor. The reference circuit of the adapter board is shown below:

When using a QSPI display, the following pins are available:

Display Pin Reference	Corresponding Net Name
GND	3V3
LCD_RS	NC*(1)*
LCD_CS	LCD_CS1/LCD_CS2*(2)*
LCD_CLK	LCD_CLK
LCD_D3	LCD_D3
LCD_D2	LCD_D2
LCD_D1	LCD_D1
LCD_D0	LCD_D0
LCD_RT	LCD_RST
VDD3.3	3V3
VDD3.3	3V3
LEDA	3V3
LEDK	LCD_LED ctrl NPN*(3)*
LCD_TE	LCD_TE
GND	3V3

[!NOTE] Note

1. RS (Register Select) may also be named DC (Data/Command). Some controllers do not define this pin, such as the GC9B72NA controller. In that case, the unused LCD_CS pin can be multiplexed as a GPIO for control.

2. Same as for the SPI display and not repeated here.

3. Same as for the SPI display and not repeated here.

When using the touch panel (TP), the following pins are available:

Touch Panel Pin Reference	Corresponding Net Name
VDD	3V3
SDA	I2C1_SDA
SCL	I2C1_SCL
INT	TP_INT
RST	TP_RST
GND	GND

Camera Interface

The camera interface provides two options: `SPI` (single-line) and `DSPI` (dual-line). The recommended controllers are `GC032A` and `BF30A2`.

Audio Interface

Codec Chip

The `ES8311` codec chip communicates with and is configured by the Cat.1 bis module through the `I2S` and `I2C` interfaces.

Microphone Interface

The main board already includes an onboard silicon microphone. If you need to connect another external electret microphone, pay attention to the terminal wire order. If the polarity is reversed, it cannot be driven. Also remove the `0 ohm` resistors at `R412/R413` and solder `2.2K ohm` resistors at `R415/R416`.

Speaker Interface

The amplifier gain should match the peak-to-peak value of the preceding audio output and the speaker to avoid volume being too low or clipping distortion. Differential input is recommended for the audio input to improve audio noise immunity.

Indicator Light Interface

RGB Indicator Light

The RGB LED communication interface complies with the `WS2812` timing specification.

Charging Indicator Light

The charging indicator lights up when USB is connected: red during normal charging and green when fully charged.

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Related Resources

• SCH-PCB(ZIP)

• TBD (XLSX)

• NTC Calculation Tool(XLSX)

• GPIO Multiplexing Table(XLSX)