Add 0x08_lcd1602_cbm bare-metal LCD1602 driver

drivers/0x08_lcd1602_cbm/Src/main.c

@@ -0,0 +1,117 @@
+/**
+  ******************************************************************************
+  * @file    main.c
+  * @author  Kevin Thomas
+  * @brief   LCD1602 demonstration: static title and live counter display.
+  *
+  *          Drives a 16x2 HD44780 LCD via a PCF8574 I2C backpack. Line 0
+  *          shows a static title ("Reverse Eng.") and line 1 displays a
+  *          counter that increments every second. The counter value is
+  *          also printed over UART for debugging.
+  *
+  *          Wiring:
+  *            GPIO0  -> UART TX (USB-to-UART adapter RX)
+  *            GPIO1  -> UART RX (USB-to-UART adapter TX)
+  *            GPIO2  -> PCF8574 backpack SDA (4.7 kohm pull-up to 3.3 V)
+  *            GPIO3  -> PCF8574 backpack SCL (4.7 kohm pull-up to 3.3 V)
+  *            3.3V   -> PCF8574 backpack VCC
+  *            GND    -> PCF8574 backpack GND
+  *
+  ******************************************************************************
+  * @attention
+  *
+  * Copyright (c) 2026 Kevin Thomas.
+  * All rights reserved.
+  *
+  * This software is licensed under terms that can be found in the LICENSE file
+  * in the root directory of this software component.
+  * If no LICENSE file comes with this software, it is provided AS-IS.
+  *
+  ******************************************************************************
+  */
+
+#include "rp2350_i2c.h"
+#include "rp2350_lcd1602.h"
+#include "rp2350_uart.h"
+#include "rp2350_xosc.h"
+#include "rp2350_delay.h"
+
+#define COUNT_DELAY_MS 1000
+
+/**
+  * @brief  Convert an unsigned 32-bit integer to a decimal string.
+  *
+  *         Writes at most 10 decimal digits plus a null terminator
+  *         into the provided buffer. The buffer must be at least
+  *         11 bytes.
+  *
+  * @param  val value to convert
+  * @param  buf destination buffer (minimum 11 bytes)
+  * @retval None
+  */
+static void _uint_to_str(uint32_t val, char *buf)
+{
+  char tmp[11];
+  int i = 0;
+  if (val == 0) {
+    buf[0] = '0';
+    buf[1] = '\0';
+    return;
+  }
+  while (val > 0) {
+    tmp[i++] = (char)('0' + (val % 10));
+    val /= 10;
+  }
+  for (int j = 0; j < i; j++)
+    buf[j] = tmp[i - 1 - j];
+  buf[i] = '\0';
+}
+
+/**
+  * @brief  Format "Count: " followed by a right-justified counter value.
+  *
+  *         Writes the formatted string into a 17-byte buffer and pads
+  *         with spaces to fill the 16-column display width.
+  *
+  * @param  count current counter value
+  * @param  buf   destination buffer (minimum 17 bytes)
+  * @retval None
+  */
+static void _format_counter(uint32_t count, char *buf)
+{
+  char num[11];
+  _uint_to_str(count, num);
+  const char *prefix = "Count: ";
+  int i = 0;
+  while (prefix[i]) { buf[i] = prefix[i]; i++; }
+  int j = 0;
+  while (num[j]) buf[i++] = num[j++];
+  while (i < 16) buf[i++] = ' ';
+  buf[i] = '\0';
+}
+
+/**
+  * @brief  Application entry point for the LCD 1602 counter demo.
+  * @retval int does not return
+  */
+int main(void)
+{
+  xosc_set_clk_ref();
+  i2c_release_reset();
+  i2c_init();
+  lcd_init();
+  uart_puts("LCD 1602 driver initialized at I2C addr 0x27\r\n");
+  lcd_set_cursor(0, 0);
+  lcd_puts("Reverse Eng.");
+  uint32_t count = 0;
+  while (1) {
+    char buf[17];
+    _format_counter(count, buf);
+    lcd_set_cursor(1, 0);
+    lcd_puts(buf);
+    uart_puts(buf);
+    uart_puts("\r\n");
+    count++;
+    delay_ms(COUNT_DELAY_MS);
+  }
+}