oled display working

hello_usb.cpp

@@ -11,9 +11,28 @@
 #include "hardware/i2c.h"
 #include "hardware/gpio.h"
 #include "pico-ssd1306/ssd1306.h"
+#include "pico-ssd1306/textRenderer/TextRenderer.h"
 
 using namespace pico_ssd1306;
 
+// Global display pointer so helper functions can update the OLED
+static SSD1306 *g_display = nullptr;
+
+// Holds last echoed line for display
+static char g_last_echo[128] = "";
+
+// Refresh OLED with current input (line 0) and last echoed text (line 2)
+static void refresh_display(const char *current_input, const char *last_echo) {
+    if (!g_display) return;
+    g_display->clear();
+    // Use next bigger font (12x16) to improve readability
+    // First line: current input
+    pico_ssd1306::drawText(g_display, font_12x16, current_input, 0, 0);
+    // Second line: last echoed text (start lower to avoid overlap)
+    pico_ssd1306::drawText(g_display, font_12x16, last_echo, 0, 20);
+    g_display->sendBuffer();
+}
+
 // Define the maximum size for the input string buffer
 #define MAX_INPUT_LEN 64
 // Define the timeout period: 5 seconds in microseconds
@@ -25,14 +44,26 @@ using namespace pico_ssd1306;
 void echo_and_reset(char* buffer, int* index_ptr) {
     if (*index_ptr > 0) {
         buffer[*index_ptr] = '\0';
+        // Print to USB serial (ALL CAPS)
         printf("\nEchoed (ALL CAPS): ");
         for (int i = 0; buffer[i] != '\0'; i++) {
-            printf("%c", toupper(buffer[i]));
+            char ch = toupper(buffer[i]);
+            printf("%c", ch);
         }
         printf("\n");
+
+        // Save last echoed (all caps) for display
+        size_t i = 0;
+        for (; buffer[i] != '\0' && i < sizeof(g_last_echo) - 1; ++i) {
+            g_last_echo[i] = (char)toupper(buffer[i]);
+        }
+        g_last_echo[i] = '\0';
     }
+
     *index_ptr = 0;
     printf("> ");
+    // Update OLED to show cleared input and last echo
+    refresh_display("", g_last_echo);
 }
 
 void wait_for_usb_connection() {
@@ -62,13 +93,20 @@ void run_echo_session() {
                 if (buffer_index > 0) {
                     buffer_index--;
                     printf("\b \b");
+                    // update display to reflect removed char
+                    input_buffer[buffer_index] = '\0';
+                    refresh_display(input_buffer, g_last_echo);
                 }
             } else if (input_char == '\r' || input_char == '\n') {
                 echo_and_reset(input_buffer, &buffer_index);
+                // after echo_and_reset the display is refreshed inside it
             } else if (buffer_index < (MAX_INPUT_LEN - 1) && isprint(input_char)) {
                 printf("%c", input_char);
                 input_buffer[buffer_index] = input_char;
                 buffer_index++;
+                // update OLED with current input
+                input_buffer[buffer_index] = '\0';
+                refresh_display(input_buffer, g_last_echo);
             }
         }
 
@@ -96,12 +134,15 @@ int main() {
 
     // Create display object (address 0x3C is common). Adjust size/address if needed.
     SSD1306 display(i2c0, 0x3C, Size::W128xH64);
+    // rotate display 180 degrees (flip). setOrientation(1) flips screen orientation
+    display.setOrientation(false);
     display.clear();
     display.sendBuffer();
-    for (int y = 0; y < 64; y++){
+
-        display.setPixel(64, y);
+    // set global pointer and show initial prompt using larger font
-    }
+    g_display = &display;
-    display.sendBuffer(); //Send buffer to device and show on screen
+    g_last_echo[0] = '\0';
+    refresh_display("> ", g_last_echo);
 
 
     while (true) {