pbio/drv/display: Add driver for Virtual Hub.

Author: laurensvalk

bricks/_common/sources.mk

@@ -148,6 +148,7 @@ PBIO_SRC_C = $(addprefix lib/pbio/,\
 	drv/counter/counter_nxt.c \
 	drv/counter/counter_stm32f0_gpio_quad_enc.c \
 	drv/display/display_ev3.c \
+	drv/display/display_virtual.c \
 	drv/gpio/gpio_ev3.c \
 	drv/gpio/gpio_stm32f0.c \
 	drv/gpio/gpio_stm32f4.c \

lib/pbio/drv/display/display_virtual.c

@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2025 The Pybricks Authors
+//
+// Display driver for a Virtual Hub
+
+#include <pbdrv/config.h>
+
+#if PBDRV_CONFIG_DISPLAY_VIRTUAL
+
+#include <stdio.h>
+#include <string.h>
+
+#include <pbdrv/display.h>
+
+#include <pbio/error.h>
+#include <pbio/image.h>
+#include <pbio/os.h>
+
+/**
+ * User frame buffer. Each value is one pixel with value:
+ *
+ *  0: Empty / White
+ *  1: Light Grey
+ *  2: Dark Grey
+ *  3: Black
+ *
+ * Non-atomic updated by the application are allowed.
+ */
+static uint8_t pbdrv_display_user_frame[PBDRV_CONFIG_DISPLAY_NUM_ROWS][PBDRV_CONFIG_DISPLAY_NUM_COLS] __attribute__((section(".noinit"), used));
+
+/**
+ * "Hardware" buffer of the virtual display.
+ */
+static uint8_t pbdrv_display_hardware_frame[PBDRV_CONFIG_DISPLAY_NUM_ROWS][PBDRV_CONFIG_DISPLAY_NUM_COLS] __attribute__((section(".noinit"), used));
+
+/**
+ * Flag to indicate that the user frame has been updated and needs to be
+ * encoded and sent to the display driver.
+ */
+static bool pbdrv_display_user_frame_update_requested;
+
+static pbio_os_process_t pbdrv_display_virtual_process;
+
+/**
+ * Display driver process. Initializes the display and updates the display
+ * with the user frame buffer if the user data was updated.
+ */
+static pbio_error_t pbdrv_display_virtual_process_thread(pbio_os_state_t *state, void *context) {
+
+    PBIO_OS_ASYNC_BEGIN(state);
+
+    // Clear display to start with.
+    memset(&pbdrv_display_user_frame, 0, sizeof(pbdrv_display_user_frame));
+    pbdrv_display_user_frame_update_requested = true;
+
+    // Update the display with the user frame buffer, if changed.
+    for (;;) {
+        PBIO_OS_AWAIT_UNTIL(state, pbdrv_display_user_frame_update_requested);
+        pbdrv_display_user_frame_update_requested = false;
+        memcpy(pbdrv_display_hardware_frame, pbdrv_display_user_frame, sizeof(pbdrv_display_hardware_frame));
+    }
+
+    PBIO_OS_ASYNC_END(PBIO_SUCCESS);
+}
+
+/**
+ * Image corresponding to the display.
+ */
+static pbio_image_t display_image;
+
+/**
+ * Initialize the display driver.
+ */
+void pbdrv_display_init(void) {
+
+    // Initialize image.
+    pbio_image_init(&display_image, (uint8_t *)pbdrv_display_user_frame,
+        PBDRV_CONFIG_DISPLAY_NUM_COLS, PBDRV_CONFIG_DISPLAY_NUM_ROWS,
+        PBDRV_CONFIG_DISPLAY_NUM_COLS);
+
+    pbio_os_process_start(&pbdrv_display_virtual_process, pbdrv_display_virtual_process_thread, NULL);
+}
+
+pbio_image_t *pbdrv_display_get_image(void) {
+    return &display_image;
+}
+
+uint8_t pbdrv_display_get_max_value(void) {
+    return 3;
+}
+
+void pbdrv_display_update(void) {
+    pbdrv_display_user_frame_update_requested = true;
+    pbio_os_request_poll();
+}
+
+#endif // PBDRV_CONFIG_DISPLAY_VIRTUAL

lib/pbio/platform/virtual_hub/pbdrvconfig.h

@@ -23,6 +23,11 @@
 
 #define PBDRV_CONFIG_COUNTER                                (1)
 
+#define PBDRV_CONFIG_DISPLAY                                (1)
+#define PBDRV_CONFIG_DISPLAY_VIRTUAL                        (1)
+#define PBDRV_CONFIG_DISPLAY_NUM_COLS                       (178)
+#define PBDRV_CONFIG_DISPLAY_NUM_ROWS                       (128)
+
 #define PBDRV_CONFIG_GPIO                                   (1)
 #define PBDRV_CONFIG_GPIO_VIRTUAL                           (1)
 

lib/pbio/platform/virtual_hub/pbioconfig.h

@@ -1,10 +1,11 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2022 The Pybricks Authors
+// Copyright (c) 2022-2025 The Pybricks Authors
 
 #define PBIO_CONFIG_BATTERY                 (1)
 #define PBIO_CONFIG_DCMOTOR                 (6)
 #define PBIO_CONFIG_DCMOTOR_NUM_DEV         (6)
 #define PBIO_CONFIG_DRIVEBASE_SPIKE         (1)
+#define PBIO_CONFIG_IMAGE                   (1)
 #define PBIO_CONFIG_LIGHT                   (0)
 #define PBIO_CONFIG_LOGGER                  (1)
 #define PBIO_CONFIG_LIGHT_MATRIX            (0)