---
title: "Captured source: Local Back Display"
description: "Captured source: Local Back Display Original ticket source file: local-back-display.h. ``c #pragma once #include #include #ifdef cplusplus extern \"C\" { #endif #define RECORDBACKD…"
doc_version: 1
last_updated: 2026-10-17
canonical_url: "http://parc.yolo.scapegoat.dev/note/projects/2026/08/03/busybar-firmware-sources/local-back-display-h"
---

# Captured source: Local Back Display

Captured source: Local Back Display Original ticket source file: local-back-display.h. ``c #pragma once #include <stdint.h> #include <stddef.h> #ifdef cplusplus extern "C" { #endif #define RECORDBACKD…

## Content

# Captured source: Local Back Display

Original ticket source file: `local-back-display.h`.

```c

#pragma once

#include <stdint.h>
#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

#define RECORD_BACK_DISPLAY "back_display"

#define BACK_DISPLAY_W        (160)
#define BACK_DISPLAY_H        (80)
#define BACK_DISPLAY_BPP      (8)
#define BACK_DISPLAY_BUF_SIZE (BACK_DISPLAY_W * BACK_DISPLAY_H * BACK_DISPLAY_BPP / 8)

typedef struct BackDisplaySrv BackDisplaySrv;

typedef struct BackDisplayContrast {
    uint8_t val;
} BackDisplayContrast;

/**
 * @brief Draw the back display data.
 *
 * @param instance back display service instance
 * @param buf back display data to draw
 * @warning this will enqueue the data to be drawn on the next frame, not immediately
 */
void back_display_draw(BackDisplaySrv* instance, const uint8_t* data);

/**
 * @brief Controls the display's power setting
 *
 * @note This configuration will not be persisted across reboots. The display is
 * always turned on on power up.
 *
 * @warning This function counts how many apps are currently keeping sleep
 * active, and only puts the display out of it once the count reaches zero. A
 * call to this function with the value of `false` is thus not guaranteed to
 * pull the display out of sleep.
 *
 * @param instance back display service instance
 * @param sleep `true` if the display is to be put into sleep (turned off),
 *              `false` if it is to be put out of sleep (turned on)
 */
void back_display_sleep_mode(BackDisplaySrv* instance, bool sleep);

/**
 * @brief Set the back display contrast
 *
 * @param instance back display service instance
 * @param contrast contrast value
 */
void back_display_set_contrast(BackDisplaySrv* instance, BackDisplayContrast contrast);

/**
 * @brief Get the width of the back display.
 *
 * @return the width of the back display
 */
size_t back_display_get_width(void);

/**
 * @brief Get the height of the back display.
 *
 * @return the height of the back display
 */
size_t back_display_get_height(void);

#ifdef __cplusplus
}
#endif

```

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