IMU Display

Lab 7: Real IMU Display (Based on Ex3)

1. โครงสร้างภาพรวมของ Lab

Why? - ทำไมต้องเรียนรู้เรื่องนี้

• Real Data: เรียนรู้การใช้ข้อมูลจาก sensor จริง (BMI270)

• IPC Architecture: เข้าใจการส่งข้อมูลระหว่าง CM33 และ CM55

• API Transition: เข้าใจการเปลี่ยนจาก simulation เป็น real hardware

What? - จะได้เรียนรู้อะไร

1. Sensor API: การใช้ aic_imu_read_accel()

2. IPC Architecture: CM33 (sensor) → Shared Memory → CM55 (UI)

3. Error Handling: การจัดการเมื่อ sensor ไม่พร้อม

4. Debug Print: การพิมพ์ข้อมูลดีบักแบบ throttled

How? - จะทำอย่างไร

1. เพิ่ม aic_sensors_init() ก่อนสร้าง UI

2. เปลี่ยน timer callback ให้ใช้ aic_imu_read_accel() แทน simulation

3. UI Code เหมือน Part I (Ex3)

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2. หลักการทำงานและ Flowchart

2.1 CM33-CM55 IPC Architecture

┌─────────────────────────────────────────────────────────────┐
│               CM33-CM55 COMMUNICATION                    │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│   ┌──────────────────┐                 ┌──────────────────┐ │
│   │       CM33       │                 │       CM55       │ │
│   │  (Sensor Core)   │                 │   (LVGL Core)    │ │
│   ├──────────────────┤                 ├──────────────────┤ │
│   │  BMI270 Driver   │                 │  LVGL Graphics   │ │
│   │  - I2C Comm      │                 │  - Chart Widget  │ │
│   │  - Raw Data Read │                 │  - Timer Update  │ │
│   └────────┬─────────┘                 └────────▲─────────┘ │
│            │                                    │           │
│            │ Write Sensor Data                  │ Read Data │
│            ▼                                    │           │
│   ┌──────────────────────────────────────────────┐          │
│   │           Shared Memory (0x261C0000)         │          │
│   │  ┌────────────────────────────────────────┐  │          │
│   │  │  update_count │  ax  │  ay  │  az  │...│  │          │
│   │  └────────────────────────────────────────┘  │          │
│   └──────────────────────────────────────────────┘          │
│                                                             │
└─────────────────────────────────────────────────────────────┘

2.2 Data Flow: Simulation vs Real

┌─────────────────────────────────────────────────────────────┐
│              PART I (SIMULATION)                            │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│   Timer (100ms)                                             │
│       │                                                     │
│       ▼                                                     │
│   simulate_imu_accel(&ax, &ay, &az)                         │
│       │                                                     │
│       ▼                                                     │
│   Scale: ax * 100  →  lv_chart_set_next_value()             │
│                                                             │
└─────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────┐
│              PART II (REAL HARDWARE)                        │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│   aic_sensors_init()  ← Initialize once at start            │
│                                                             │
│   Timer (100ms)                                             │
│       │                                                     │
│       ▼                                                     │
│   aic_imu_read_accel(&ax, &ay, &az)                         │
│       │                                                     │
│       ├── return false → return (sensor not ready)          │
│       │                                                     │
│       ▼  return true                                        │
│   Scale: ax * 100  →  lv_chart_set_next_value()             │
│                                                             │
└─────────────────────────────────────────────────────────────┘

2.3 UI Layout (Same as Ex3)

┌─────────────────────────────────────────────────────────────┐
│       "Week 4 Ex7: Real IMU (Based on Ex3)"                 │
├─────────────────────────────────────────────────────────────┤
│      "Accelerometer - REAL BMI270 DATA"                     │
│  ┌───────────────────────────────────────────────────────┐  │
│  │                  LINE CHART                           │  │
│  │   3 Series:                                           │  │
│  │   - X (Red)   ────────────────                        │  │
│  │   - Y (Green) ────────────────                        │  │
│  │   - Z (Blue)  ────────────────                        │  │
│  │                                                       │  │
│  │   50 points, Y range: -1500 to +1500                  │  │
│  └───────────────────────────────────────────────────────┘  │
│                                          X: +0.50           │
│                                          Y: -0.30           │
│                                          Z: +9.81           │
│      "[Part II] Using aic_imu_read_accel()"                 │
└─────────────────────────────────────────────────────────────┘

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3. ฟังก์ชันสำคัญ

3.1 Sensor API Functions

Function	Description
aic_sensors_init()	Initialize sensor subsystem (call once)
aic_imu_read_accel(&ax, &ay, &az)	Read accelerometer (m/s²)
aic_imu_read_gyro(&gx, &gy, &gz)	Read gyroscope (rad/s)

3.2 Return Values

/* Returns true if data is valid, false if sensor not ready */
bool aic_imu_read_accel(float *ax, float *ay, float *az);
bool aic_imu_read_gyro(float *gx, float *gy, float *gz);

3.3 Key Differences from Part I

Item	Part I (Simulation)	Part II (Real Hardware)
Init	(none)	aic_sensors_init()
Read	simulate_imu_accel()	aic_imu_read_accel()
Error	Always returns	May return false
Range	Predictable	Real sensor noise

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4. Code Example

4.1 Header Includes

#include "week4_examples.h"
#include "../aic-eec/aic-eec.h"
#include "../aic-eec/sensors.h"
#include "../../shared/imu_shared.h"  /* For IPC debug */

4.2 Timer Callback (Real IMU)

static void ex7_timer_cb(lv_timer_t * timer)
{
    (void)timer;

    /* Read REAL accelerometer data */
    float ax, ay, az;
    if(!aic_imu_read_accel(&ax, &ay, &az)) {
        return;  /* IMU not ready - skip this update */
    }

    /* Scale to int for chart (multiply by 100) */
    int32_t x_val = (int32_t)(ax * 100);
    int32_t y_val = (int32_t)(ay * 100);
    int32_t z_val = (int32_t)(az * 100);

    /* Add new points */
    lv_chart_set_next_value(ex7_chart, ex7_ser_x, x_val);
    lv_chart_set_next_value(ex7_chart, ex7_ser_y, y_val);
    lv_chart_set_next_value(ex7_chart, ex7_ser_z, z_val);

    /* Update labels */
    lv_label_set_text_fmt(ex7_labels[0], "X: %+.2f", (double)ax);
    lv_label_set_text_fmt(ex7_labels[1], "Y: %+.2f", (double)ay);
    lv_label_set_text_fmt(ex7_labels[2], "Z: %+.2f", (double)az);

    /* Debug print (throttled - every 10 updates) */
    static uint32_t count = 0;
    count++;
    if (count % 10 == 0) {
        printf("[IMU] X:%+.2f Y:%+.2f Z:%+.2f\r\n",
               (double)ax, (double)ay, (double)az);
    }
}

4.3 Main Function

void week4_ex7_real_imu_display(void)
{
    /* ===== HARDWARE INITIALIZATION ===== */
    aic_sensors_init();

    /* ===== UI CODE (Same as Part I Ex3) ===== */

    /* Background */
    lv_obj_set_style_bg_color(lv_screen_active(),
                              lv_color_hex(0x16213e), LV_PART_MAIN);

    /* Title */
    lv_obj_t * title = lv_label_create(lv_screen_active());
    lv_label_set_text(title, "Week 4 Ex7: Real IMU (Based on Ex3)");
    lv_obj_set_style_text_color(title, lv_color_hex(0xFFFFFF), 0);
    lv_obj_align(title, LV_ALIGN_TOP_MID, 0, 10);

    /* Create Chart */
    ex7_chart = lv_chart_create(lv_screen_active());
    lv_obj_set_size(ex7_chart, 440, 260);
    lv_obj_align(ex7_chart, LV_ALIGN_CENTER, -10, 10);
    lv_chart_set_type(ex7_chart, LV_CHART_TYPE_LINE);
    lv_chart_set_point_count(ex7_chart, 50);

    /* Range: -1500 to 1500 (for ±15 m/s² x 100) */
    lv_chart_set_range(ex7_chart, LV_CHART_AXIS_PRIMARY_Y, -1500, 1500);

    /* Hide points */
    lv_obj_set_style_size(ex7_chart, 0, 0, LV_PART_INDICATOR);
    lv_obj_set_style_line_width(ex7_chart, 2, LV_PART_ITEMS);

    /* Add series */
    ex7_ser_x = lv_chart_add_series(ex7_chart,
                    lv_palette_main(LV_PALETTE_RED),
                    LV_CHART_AXIS_PRIMARY_Y);
    ex7_ser_y = lv_chart_add_series(ex7_chart,
                    lv_palette_main(LV_PALETTE_GREEN),
                    LV_CHART_AXIS_PRIMARY_Y);
    ex7_ser_z = lv_chart_add_series(ex7_chart,
                    lv_palette_main(LV_PALETTE_BLUE),
                    LV_CHART_AXIS_PRIMARY_Y);

    /* ... value labels ... */

    /* Timer - uses REAL IMU data */
    ex7_timer = lv_timer_create(ex7_timer_cb, 100, NULL);
}

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5. องค์ความรู้และเทคนิค

5.1 Error Handling Pattern

/* Always check return value before using data */
float ax, ay, az;
if(!aic_imu_read_accel(&ax, &ay, &az)) {
    return;  /* Exit early - don't update UI */
}
/* Safe to use ax, ay, az here */

5.2 Debug Print Throttling

/* Print every N updates to avoid console flood */
static uint32_t count = 0;
count++;
if (count % 10 == 0) {  /* Print every 1 second (at 100ms interval) */
    printf("[IMU] ...\r\n");
}

5.3 Shared Memory Debug

/* Check CM33 update count to verify IPC is working */
uint32_t cm33_count = IMU_SHARED_GET_COUNT();
printf("CM33 count: %u, CM55 count: %u\r\n",
       (unsigned int)cm33_count, (unsigned int)count);

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6. แบบฝึกหัด

Exercise 1: Magnitude Chart

เพิ่ม series สำหรับ magnitude (sqrt(x² + y² + z²)) บน chart เดียวกัน

Exercise 2: Moving Average Filter

ใส่ Moving Average Filter เพื่อลด noise:

filtered = 0.8 * filtered + 0.2 * raw

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7. References

• LVGL Chart

• PSoC Edge BMI270 IMU

• Inter-Processor Communication

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Previous Lab: Lab 6: Chart Dashboard Next Lab: Lab 8: Real Sensor Dashboard