MiniEVB LGT8F328P

The term MiniEVB refers to small boards available in various sizes that are mostly compatible with Arduino. These use microcontrollers of the type LGT8F328P from the manufacturer LogicGreen (now: Prodesign Semiconductor) with an instruction set largely compatible with the ATmega328P, but with some enhancements. This article focuses on the so-called Nano Style LQFP32 MiniEVB, where the pins and their positions along the long sides match those of the Arduino Nano.

Features/Specifications

This board comes in two versions:

• The green board has a Micro-USB port, only an internal oscillator, and uses the HT42B534-2 as a USB-TTL converter. According to the datasheet, the internal oscillator has a deviation of up to 1% (10000ppm), which in practice could result in a deviation of up to 864 seconds per day.
• The purple board features a USB-C connector, a 16 MHz oscillator, and uses the CH9340C USB-to-TTL chip. Both variants share the same pinout. The advantages of the purple board over the green one include lower power consumption and more accurate timing thanks to the external oscillator (useful for time-critical applications). According to the datasheet, the maximum deviation is between 10–100ppm, which would result in a deviation of 8.6 seconds per day.

MiniEVB LGT8F328P vs. Arduino Nano

• Different ISP interface
• 4 additional GPIOs: PE0, PE2, PE4, PE5 (2 of which can be used as ISP interface)
• No fuses

Connections

The pinout of the LGT8F328P Nano board is nearly identical to that of the Arduino Nano, with a few differences:
There are 5 additional digital input/output pins; AREF, A6, and A7 can be used as digital pins, and the SWC and SWD pins are also available.

Used Components

Programming with the Arduino IDE

Add Board Manager URL

To compile and upload sketches for LGT8F328P Nano boards using the Arduino IDE, some initial setup is required. Go to "Preferences → Additional Board Manager URLs" and add the following URL: https://raw.githubusercontent.com/dbuezas/lgt8fx/master/package_lgt8fx_index.json
If another URL is already present in this field, it can be separated using a comma:

Install LGT8F328P Nano Board

Next, the LGT8F328P Nano board must be installed. Go to "Tools → Board → Board Manager". Search for "lgt8fx" and install "LGT8fx Boards by dbuezas".

Select Port

Now connect the LGT8FX to the PC via USB and select the port under "Tools → Port:".
If the COM port is not available on Windows, you may need to install the USB to UART Bridge.

Test-Program

For the first test, I used a slightly modified Blink-sketch. This can be compiled and uploaded just like with a standard Arduino:

void setup() {
    pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
    for (byte i=0; i

Analog-Digital Converter (ADC)

Since the ADC can handle higher resolution and reference voltages, analog signals can be resolved more finely. The following experiment is similar in setup to the one from LDR GL55xx (without the LED). However, instead of the LDR, a potentiometer, piezo transducer, or similar could also be used.

/*
    Parameter:      Voltage reference:
    ----------------------------------------
    DEFAULT         VCC
    EXTERNAL        External Reference (REF)
    INTERNAL1V024   Internal 1.024 volts
    INTERNAL2V048   Internal 2.048 volts
    INTERNAL4V096   Internal 4.096 volts
*/

void setup() {
    Serial.begin(9600);
    analogReference(INTERNAL4V096);

    // 10, 11, or 12 bit
    analogReadResolution(12);
}

void loop() {
    int v = analogRead(A0);
    float voltage = v * 4.096 / 4096.0;
    Serial.print("Value:   " + String(v) + "\t\t");
    Serial.println("Voltage: " + String(voltage) + " V");
    delay(50);
}

Digital-Analog Converter (DAC)

On pin #4 (D4 / PD4 / DAO), a real analog signal can be generated with a resolution of 8 bits:

void setup() {
    analogReference(DEFAULT);
    pinMode(DAC0, ANALOG);
    analogWrite(DAC0, 69); // 0...255
}

void loop(){}

Watchdog Timer (WDT)

Since the Watchdog works a bit differently compared to the Arduino Nano, it is recommended to use the dbuezas/WDT library instead of the avr/wdt.h library. In the following sketch, only the line wdt_reset() needs to be uncommented, and the sketch will run continuously.

/*
    Parameter       WDT reset period
    --------------------------------
    WTO_64MS         64 ms
    WTO_128MS       128 ms
    WTO_256MS       256 ms
    WTO_512MS       512 ms
    WTO_1S            1 s
    WTO_2S            2 s
    WTO_4S            4 s
    WTO_8S            8 s
    WTO_16S          16 s
    WTO_32S          32 s
*/

#include "WDT.h"

void setup() {
    pinMode(LED_BUILTIN, OUTPUT);
    digitalWrite(LED_BUILTIN, LOW);
    Serial.begin(9600);
    Serial.println("Start");
    wdt_enable(WTO_4S);
}

void loop() {
    Serial.println("Elapsed time: " + String(millis()) + "ms");
    delay(888);
    // wdt_reset();
}

Heat radiation

Further information

• MiniEVB Boards – An Overview
• LGT8F328P – LQFP32 Boards
• LGT8fx Boards for Arduino IDE