Verifying The Functionality of VSD Mini Squadron Board By Implementing a Centade (0-99) BCD Counter

BCD stands for Binary-Coded Decimal. A BCD counter is a type of counter used in digital electronics and computing to represent decimal numbers using binary-coded decimal format. In BCD format, each decimal digit (0-9) is represented by a 4-bit binary code.

  • Decimal 0 is represented as 0000 in BCD.
  • Decimal 4 is represented as 0100 in BCD.
  • Decimal 15 is represented as 0001 0101 in BCD.

  • VSD Mini Squadron Board
  • 8 LEDs ( 4 Blue & 4 Red )
  • Eight 220 ohm Resistors
  • Push button switch
  • Jumper cables
  • Bread board
  • USB type-C or a 3.3V DC power source

As we can see from the above image,

  • A push button which act as trigger is connected between GND & PD1.
  • All the 8 LEDs have a common GND & each of their Anode is connected to a 220 ohms resistors.
  • Ports PC0 to PC3 forms the unit digit & are connected to their respective LEDs with PC0 being LSB (Least Significant Bit) & PC3 being MSB (Most Significant Bit)
  • Similarly, Ports PD2 to PD5 forms the tens digit & are connected to their respective LEDs with PD2 being LSB (Least Significant Bit) & P being MSB (Most Significant Bit)

As we know the VSD Mini Board can be programmed in embedded C, below is the C code which programs the board to act as a BCD counter.

#include <ch32v00x.h>

// Define GPIO pins for the LEDs
#define UNIT_LSB_PIN GPIO_Pin_0  // LSB of the units digit
#define UNIT_MSB_PIN GPIO_Pin_3  // MSB of the units digit
#define TENS_LSB_PIN GPIO_Pin_2  // LSB of the tens digit
#define TENS_MSB_PIN GPIO_Pin_5  // MSB of the tens digit

// Function to initialize GPIO pins
void GPIO_Config(void) {
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOD, ENABLE);

    // Configure the reading pin on port D as digital input
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; // Input with pull-up
    GPIO_Init(GPIOD, &GPIO_InitStructure);

    // Configure LEDs for units digit on port C as output
    GPIO_InitStructure.GPIO_Pin = UNIT_LSB_PIN | GPIO_Pin_1 | GPIO_Pin_2 | UNIT_MSB_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOC, &GPIO_InitStructure);

    // Configure LEDs for tens digit on port D as output
    GPIO_InitStructure.GPIO_Pin = TENS_LSB_PIN | GPIO_Pin_3 | GPIO_Pin_4 | TENS_MSB_PIN;
    GPIO_Init(GPIOD, &GPIO_InitStructure);

// Function to update the BCD counter display
void UpdateDisplay(uint8_t tens, uint8_t units) {
    GPIO_Write(GPIOC, (GPIO_ReadOutputData(GPIOC) & 0xFFF0) | units); // Write units digit to port C
    GPIO_Write(GPIOD, (GPIO_ReadOutputData(GPIOD) & 0xFFC3) | (tens << 2));  // Write tens digit to port D

// Simple delay function
void delay(uint32_t count) {
    while(count--) {
        __NOP(); // Do nothing (NOP instruction)

int main(void) {
    uint8_t units = 0, tens = 0;
    int prevButtonState = 1; // Initialize to high

    GPIO_Config(); // Configure the GPIO

    while(1) {
        // Read the button state from pin D1
        int buttonState = GPIO_ReadInputDataBit(GPIOD, GPIO_Pin_1);

        // Detect negative edge (1 to 0 transition)
        if(!buttonState && prevButtonState) {
            // Increment the BCD counter
            if(units > 9) {
                units = 0;
                if(tens > 9) {
                    tens = 0;
            UpdateDisplay(tens, units); // Update the BCD display
        prevButtonState = buttonState; // Update the previous button state

        delay(10000); // Debounce delay

The board is programmed to continuously monitor the voltage/state at port PD1. Upon detecting a negedge, which is the transition of voltage from 3.3v to 0v, it will increment the counter to the next state. This can be observed in the below video.

Registration for Ethical RISC-V IoT Workshop

Welcome to Ethical RISC-V IoT Workshop

The “Ethical RISC-V IoT Workshop” at IIIT Bangalore, organized in collaboration with VSD, is a structured, educational competition aimed at exploring real-world challenges in IoT and embedded systems. Participants progress through three stages: building an application, injecting and managing faults, and enhancing application security. The event spans from May 9 to June 15, 2024, culminating in a showcase of top innovations and an award ceremony. This hands-on hackathon emphasizes learning, testing, and securing applications in a collaborative and competitive environment.

Rules :
  1. Only for Indian Student whose college is registered under VTU
  2. Only team of 2 members can Register
  3. Use only VSDSquadron Mini resources for product development
Awards :
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  2. 3 Winner team’s Product will be evaluated for Incubation
  3. 7 consolation prizes
  4. Completion Certificate to final round qualifier
  5. Chance to build a Proud Secured RISC-V Platform for India

Date for Registration : 9th May - 22nd May, 2024
Hackathon Inauguration : 23rd May 2024

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