lgt

+- [[LGT-dat]] - [[LGT8F328-DAT]] - [[DAR1056-DAT]] - [[CIC1053-dat]] - [[NWL1097-dat]]

+

+

+| pin | LGT | extra |

+| --- | ----- | ----- |

+| 4 | VCC | |

+| 5 | GND | |

+| 18 | SWC | PE0 |

+| 21 | SWD | PE2 |

+| 29 | Reset | |

+- [[TQFP-dat]]

+## Sketch uploads By Arduino IDE

+

+

+

+## bootloader

+

+C:\Users\Administrator\AppData\Local\Arduino15\packages\lgt8fx\hardware\avr\2.0.7\bootloaders\lgt8fx8e\optiboot_lgt8f328d.hex

+

+C:\Users\Administrator\AppData\Local\Arduino15\packages\lgt8fx\hardware\avr\2.0.7\bootloaders\lgt8fx8p\optiboot_lgt8f328p.hex

+

+

+## LGT8F328D

+

+- error blink LED

+- optiboot_lgt8f328d_intosc.hex

+

+

+

+

+

+- [[LGT8F328-dat]] - [[LGT-dat]]

+

+- [[avr-dat]]

+

+- [[fab-dat]]

+- [[AVR-app-dat]] - [[avr-fuse-dat]]

+

+# avr-fuse-dat

+

+AVR Fuses: The "BIOS" of Your Microcontroller

+

+In AVR microcontrollers (like the ATmega328P used in the Arduino Uno), **fuses** are configuration bits that determine the fundamental hardware behavior of the chip. Unlike your application code, fuses are not erased when you upload a new program; they are stored in a separate, non-volatile memory space.

+

+### 1. Key Responsibilities

+Fuses tell the hardware how to "wake up" and function at a physical level. Common configurations include:

+

+* **Clock Source Selection:** Choosing between an internal RC oscillator, an external crystal, or an external clock.

+* **Clock Divider:** A factory-set fuse (`CKDIV8`) that often slows the chip down to 1MHz by default.

+* **Brown-out Detector (BOD):** Triggers a reset if the supply voltage drops below a safe threshold (e.g., 2.7V or 4.3V) to prevent data corruption.

+* **Bootloader Support:** Defines how much memory to reserve for a bootloader and where the execution starts after a reset.

+* **Watchdog Timer (WDT):** Can be permanently enabled via fuses to reset the chip if the software hangs.

+

+---

+

+### 2. The Binary Logic (Important!)

+AVR fuses use **inverse logic**, which is often counter-intuitive for developers:

+* **0 = Programmed (Active/Enabled)**

+* **1 = Unprogrammed (Disabled/Off)**

+

+> **Note:** If you want to enable a feature, you usually set its bit to `0`.

+

+---

+

+### 3. Fuse Byte Structure

+Most modern AVRs organize fuses into three main bytes:

+

+| Byte | Primary Function | Example Impact |

+| :---------------- | :---------------------------- | :--------------------------------------------- |

+| **Low Fuse** | Clock settings & Startup time | Determines how fast the chip runs. |

+| **High Fuse** | Bootloader, SPI, & Reset | Can disable the ability to reprogram the chip. |

+| **Extended Fuse** | Brown-out Detection | Controls stability during power fluctuations. |

+

+

+

+---

+

+### 4. Risks: "Bricking" the Chip

+Fuses are powerful and can "brick" your microcontroller if set incorrectly:

+* **Wrong Clock:** If you select an "External Crystal" but don't have one soldered to the board, the chip will have no heartbeat and will stop responding to programmers.

+* **Disable Reset:** If you disable the `RSTDISBL` fuse to gain an extra I/O pin, you can no longer use standard ISP programmers to change your code.

+* **Disable SPI:** Disabling the `SPIEN` fuse prevents further programming via the standard Serial Peripheral Interface.

+

+---

+

+### 5. How to Change Them

+Fuses cannot be changed by the code running *on* the chip. You must use an external hardware programmer (like a USBasp, AVRISP mkII, or another Arduino acting as an "ArduinoISP") and software like **AVRDUDE**.

+

+**Example AVRDUDE command to set fuses:**

+`avrdude -c usbasp -p m328p -U lfuse:w:0xFF:m`

+

+

+

+

+## Arduino Uno (ATmega328P) Typical Fuse Settings

+

+The following values are the standard configuration for a 5V, 16MHz Arduino Uno:

+

+| Fuse Byte | Hex Value | Binary Value | Key Functions Enabled |

+| :------------ | :-------- | :----------- | :-------------------------------------------- |

+| **Low Fuse** | `0xFF` | `11111111` | External Crystal (16MHz), Max Start-up Time. |

+| **High Fuse** | `0xDE` | `11011110` | SPI Programming Enabled, 512-word Bootloader. |

+| **Extended** | `0xFD` | `11111101` | Brown-out Detection (BOD) set to 2.7V. |

+

+---

+

+### 1. Low Fuse (0xFF) Breakdown

+The Low Fuse primarily handles the **Clock Source**.

+* **0xFF** tells the chip: "Don't use the internal oscillator; wait for an external 16MHz crystal to stabilize before starting."

+* It also disables the `CKDIV8` (Divide clock by 8) bit. If this were set to `0x7F`, your 16MHz Arduino would crawl at 2MHz.

+

+

+

+### 2. High Fuse (0xDE) Breakdown

+The High Fuse manages **System features** and **Bootloader memory**.

+* **SPIEN (Bit 5):** Set to `0` (Enabled) so you can program it via the ICSP header.

+* **BOOTSZ (Bits 2-1):** Set to reserve 512 words (1024 bytes) for the Optiboot bootloader.

+* **BOOTRST (Bit 0):** Set to `0` (Enabled) so the chip jumps to the bootloader address immediately upon power-up instead of starting the user sketch.

+

+### 3. Extended Fuse (0xFD) Breakdown

+

+This byte is almost exclusively for **Brown-out Detection (BOD)**.

+* **0xFD** sets the threshold to **2.7V**.

+* If the power supply dips below 2.7V, the chip will force a reset. This prevents the processor from executing "garbage" instructions or corrupting EEPROM memory when the voltage is too low for stable logic.

+

+## CNV-TQFP32

+

+ pin 5 = pin 1

+ pin 6 = pin 2

+ pin 7 = pin 3

+ pin 8 = pin 4

+ pin 9 = pin 5

+

+ pin 22 = pin 18

+ pin 23 = pin 19

+ pin 24 = pin 20

+ pin 25 = pin 21

+

+

+

+

+

+

+

+

+

+

+# fab-PCB-soldering-skills-dat

+

+- to resolder a chip, and to keep all the pins well contact, add weight on the chip to gain better contact

+

+

+

+

+

+

+

+

+

+- [[user-friendly-mechanical-design-dat]]

+

+# user-friendly-mechanical-design-dat

+

+

+- fast-lock

+- Wing-Nut (羊角) / wing-screw

+

+

+

+