added firmware section

firmware/.gitignore

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+# Compiled binaries
+*.elf
+*.bin
+*.hex
+
+# Build artifacts and memory maps
+*.map
+*.o
+*.d
+*.lst
+
+# Specifically ignore the output files for our target
+main.elf
+main.bin
+main.map

firmware/Makefile

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+all : flash
+
+TARGET:=main
+TARGET_MCU:=CH32V003
+
+# Path based on your error output
+CH32FUN:=/home/martin/ch32fun/ch32fun
+
+include $(CH32FUN)/ch32fun.mk
+
+flash : cv_flash
+clean : cv_clean

firmware/Readme.md

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+# CH32V003 Firmware & Linux Development Setup
+
+This folder contains the firmware source code for the CNC Water Flow Controller, built using the [ch32fun](https://github.com/cnlohr/ch32fun) framework. 
+
+Below is the guide to set up the build environment, compile, and flash the CH32V003 series on Linux using CLI tools.
+
+*Tested on: Ubuntu Linux, CH32V003J4M6 (8-pin)*
+
+---
+
+## 1. Install toolchain
+
+Download xPack RISC-V GCC:
+[https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases](https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases)
+
+Extract it:
+```bash
+mkdir -p ~/toolchains
+tar -xzf xpack-riscv-none-elf-gcc-*-linux-x64.tar.gz -C ~/toolchains
+```
+
+Activate it (add this to your ~/.bashrc for permanence):
+```Bash
+export TOOLCHAIN=$HOME/toolchains/xpack-riscv-none-elf-gcc-* # Update e.g.: xpack-riscv-none-elf-gcc-15.2.0-1
+export PATH=$TOOLCHAIN/bin:$PATH
+```
+
+Verify the installation:
+```Bash
+riscv-none-elf-gcc --version
+```
+
+## 2. Install Flashing Tool (minichlink)
+Clone the ch32fun repository and build minichlink:
+```Bash
+git clone https://github.com/cnlohr/ch32fun ~/ch32fun
+cd ~/ch32fun/minichlink
+make
+sudo mv minichlink /usr/local/bin/
+```
+
+## 3. Build the Firmware
+Navigate to this firmware directory where the Makefile and main.c are located. Make sure the CH32FUN path in the Makefile points to where you cloned ch32fun.
+```Bash
+cd Flow-Controller/firmware
+make clean
+make
+```
+This will generate main.bin and main.elf.
+
+## 4. Flash Firmware
+Connect your WCH-LinkE programmer to the board's J1 header:
+| Signal | Programmer | MCU Header (J1) |
+| :--- | :--- | :--- |
+| SWIO | SWDIO | Pin 3 (SWIO) |
+| GND | GND | Pin 2 (GND) |
+| 5V | 3.3V | Pin 1 (+3.3V) |
+Flash the compiled binary:
+```Bash
+make flash
+```
+or manually: 
+```bash
+minichlink -w main.bin flash
+```
+
+## 5. Logs
+See logs on the SWIO pin:
+```Bash
+minichlink -T
+```
+
+## 6. Unbricking
+If you accidentally misconfigure the SWIO pin and lock yourself out, you can use the CH32V003 Unbrick CLI tool:
+```Bash
+git clone https://github.com/shakir-abdo/ch32v003-unbrick.git
+cd ch32v003-unbrick
+npm install
+./unbrick.js
+```

firmware/funconfig.h

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+#ifndef _FUNCONFIG_H
+#define _FUNCONFIG_H
+
+#define CH32V003 1
+
+// Default system clock to 48MHz
+#define FUNCONF_SYSTEM_CORE_CLOCK 48000000
+
+// support "printf-over-single-wire" at about 400kBaud on the SWIO pin (PD1)
+#define FUNCONF_USE_DEBUGPRINTF 1
+#define FUNCONF_USE_UARTPRINTF  0
+
+#endif // _FUNCONFIG_H

firmware/main.c

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+#include "ch32fun.h"
+#include <stdio.h>
+
+// ==========================================
+// PIN CONFIGURATION (CH32V003J4M6 - SOP8)
+// ==========================================
+// Package Pin 1: PD6 (FLOW_PULSE_MCU) -> EXTI Input
+// Package Pin 3: PA2 (ALARM_TRIGGER)  -> GPIO Output
+// Package Pin 5: PC1 (I2C_SDA)        -> Bitbang or HW I2C
+// Package Pin 6: PC2 (I2C_SCL)        -> Bitbang or HW I2C
+// Package Pin 7: PC4 (BUTTON_ADC)     -> ADC Channel 2 Input
+// Package Pin 8: PD1 (SWIO) -> Programming & Logging
+
+#define FLOW_PIN      6 // PD6 = bit 6 of GPIOD
+#define ALARM_PIN     2 // PA2 = bit 2 of GPIOA
+#define BUTTON_PIN    4 // PC4 = bit 4 of GPIOC
+
+// Constants
+#define FLOW_CONVERSION_FACTOR 5.5  // L/min = Hz / 5.5 (Adjust for ZJ-S401)
+
+#define ADC_UP_BTN_MAX     200  // Button 1 range: 50..200  (center ~93)
+#define ADC_UP_BTN_MIN      20
+#define ADC_DOWN_BTN_MAX    15  // Button 2 range: 0..15    (should read ~0)
+
+#define DEBOUNCE_DELAY_MS   200
+
+// Globals
+volatile uint32_t pulse_count = 0;
+uint32_t flow_rate_ml_min = 0;    // Stored in mL/min for integer precision
+uint32_t threshold_ml_min = 2000; // Default: 2.0 L/min
+uint8_t  alarm_active = 0;        // Track state to prevent log spam (0 = OK, 1 = ALARM)
+
+// ==========================================
+// INTERRUPT HANDLER (Flow Sensor Pulses)
+// ==========================================
+void EXTI7_0_IRQHandler(void) __attribute__((interrupt));
+void EXTI7_0_IRQHandler(void) {
+    if (EXTI->INTFR & (1 << FLOW_PIN)) {
+        pulse_count++;
+        EXTI->INTFR = (1 << FLOW_PIN); // Clear interrupt flag
+    }
+}
+
+// ==========================================
+// HARDWARE INITIALIZATION
+// ==========================================
+void Init_Hardware(void) {
+    // 1. Enable Clocks for GPIOA, GPIOC, GPIOD, ADC, AFIO
+    RCC->APB2PCENR |= RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOD | RCC_APB2Periph_ADC1 | RCC_APB2Periph_AFIO;
+
+    // 2. Configure ALARM_TRIGGER Output (PA2) - Push-Pull
+    GPIOA->CFGLR &= ~(0xF << (4 * ALARM_PIN));
+    GPIOA->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP) << (4 * ALARM_PIN);
+    GPIOA->BSHR = (1 << (16 + ALARM_PIN)); // Default to ALARM STATE (Low = MOSFET OFF)
+
+    // 3. Configure FLOW_PULSE_MCU Input (PD6) - Pull-up
+    GPIOD->CFGLR &= ~(0xF << (4 * FLOW_PIN));
+    GPIOD->CFGLR |= (GPIO_CNF_IN_PUPD) << (4 * FLOW_PIN);
+    GPIOD->BSHR = (1 << FLOW_PIN); // Enable pull-up
+
+    // Setup EXTI on PD6 (CH32V003 has single EXTICR, 2 bits per pin, Port D = 0b11)
+    AFIO->EXTICR |= (0b11 << (FLOW_PIN * 2));   // PD6: Port D=0b11, bits [13:12]
+    EXTI->INTENR |= (1 << FLOW_PIN);             // Enable EXTI interrupt on line 6
+    EXTI->FTENR  |= (1 << FLOW_PIN);             // Falling edge trigger
+    NVIC_EnableIRQ(EXTI7_0_IRQn);                // Enable interrupt in NVIC
+
+    // 4. Configure BUTTON_ADC Input (PC4 / AIN2) - Analog mode (no pull)
+    GPIOC->CFGLR &= ~(0xF << (4 * BUTTON_PIN));
+
+    // Setup ADC
+    ADC1->CTLR2 |= ADC_ADON;       // Turn on ADC
+    ADC1->RSQR3 = 2;               // PC4 is ADC Channel 2 (AIN2)
+    ADC1->SAMPTR2 = 7 << (3 * 2);  // Max sampling time for CH2
+
+    ADC1->CTLR2 |= ADC_RSTCAL;     // Reset & calibrate
+    while(ADC1->CTLR2 & ADC_RSTCAL);
+    ADC1->CTLR2 |= ADC_CAL;
+    while(ADC1->CTLR2 & ADC_CAL);
+}
+
+// ==========================================
+// HELPER FUNCTIONS
+// ==========================================
+uint16_t Read_ADC(void) {
+    ADC1->CTLR2 |= ADC_SWSTART;
+    while(!(ADC1->STATR & ADC_EOC));
+    return ADC1->RDATAR;
+}
+
+void Update_Display(uint32_t current_flow, uint32_t threshold) {
+    // TODO: Implement OLED I2C drawing here using ch32fun's I2C bitbang
+}
+
+// ==========================================
+// MAIN LOOP
+// ==========================================
+int main() {
+    SystemInit();
+    Init_Hardware();
+
+    printf("\r\n==================================\r\n");
+    printf(" CNC Flow Controller Initialized\r\n");
+    printf("==================================\r\n");
+    printf("[INFO] Active Threshold: %lu mL/min\r\n", threshold_ml_min);
+
+    uint32_t last_time = SysTick->CNT;
+    uint32_t last_button_time = 0;
+
+    while(1) {
+        uint32_t current_time = SysTick->CNT;
+        uint32_t ticks_per_sec = DELAY_US_TIME * 1000000; // = FUNCONF_SYSTEM_CORE_CLOCK
+
+        // --- 1. EVALUATE FLOW EVERY 1 SECOND ---
+        if ((current_time - last_time) >= ticks_per_sec) {
+            last_time = current_time;
+
+            // Copy and reset pulse count safely
+            NVIC_DisableIRQ(EXTI7_0_IRQn);
+            uint32_t hz = pulse_count;
+            pulse_count = 0;
+            NVIC_EnableIRQ(EXTI7_0_IRQn);
+
+            // Calculate Flow: L/min = Hz / 5.5 => mL/min = (Hz * 10000) / 55
+            flow_rate_ml_min = (hz * 10000) / 55;
+
+            // --- 2. FAILSAFE LOGIC & LOGGING ---
+            if (flow_rate_ml_min >= threshold_ml_min) {
+                // Flow OK -> Drive ALARM_PIN High (MOSFET ON, CNC OK)
+                GPIOA->BSHR = (1 << ALARM_PIN);
+
+                if (alarm_active == 1) {
+                    alarm_active = 0;
+                    printf("[INFO] Flow restored: %lu mL/min. Alarm CLEARED.\r\n", flow_rate_ml_min);
+                }
+            } else {
+                // Flow Low -> Drive ALARM_PIN Low (MOSFET OFF, CNC Alarm)
+                GPIOA->BSHR = (1 << (16 + ALARM_PIN));
+
+                if (alarm_active == 0) {
+                    alarm_active = 1;
+                    printf("[WARN] Low flow detected: %lu mL/min (Thr: %lu). Alarm TRIGGERED!\r\n", flow_rate_ml_min, threshold_ml_min);
+                }
+            }
+
+            Update_Display(flow_rate_ml_min, threshold_ml_min);
+        }
+
+        // --- 3. BUTTON HANDLING (ADC Resistor Ladder) ---
+        // Thresholds match actual voltages: no-press ~1023, BTN1 ~93, BTN2 ~0.
+        uint16_t adc_val = Read_ADC();
+
+        if ((current_time - last_button_time) > (DEBOUNCE_DELAY_MS * DELAY_US_TIME * 1000)) {
+            if (adc_val >= ADC_UP_BTN_MIN && adc_val <= ADC_UP_BTN_MAX) {
+                // Button 1: voltage divider 10k+1k -> ~0.30V -> ADC ~93
+                threshold_ml_min += 100;
+                last_button_time = current_time;
+                printf("[SET] Threshold increased to: %lu mL/min\r\n", threshold_ml_min);
+                Update_Display(flow_rate_ml_min, threshold_ml_min);
+            }
+            else if (adc_val <= ADC_DOWN_BTN_MAX) {
+                // Button 2: direct to GND -> ~0V -> ADC ~0
+                if (threshold_ml_min >= 100) threshold_ml_min -= 100;
+                last_button_time = current_time;
+                printf("[SET] Threshold decreased to: %lu mL/min\r\n", threshold_ml_min);
+                Update_Display(flow_rate_ml_min, threshold_ml_min);
+            }
+        }
+    }
+}