Several important conclusions of AVR microcontroller

Single chip microcomputer STM32L151CCU6

1206RGB (single)

0201 package SLP0603 ESD electrostatic diode 5V one-way ESD

Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ) 7.5PF 10PPM 20PPM 30PPM

Probe orientation needle 265*2980 needle head diameter is 6.0 end probe needle

When I switched to ST and AVR, I didn't systematically read related documents. According to the project, I got the datasheet and prepared the tools. The most visible ones are features and pins, so I often neglected in some details. After experiencing the painful lesson, sum up some. . . .

1. When downloading the program to Tiny25 through the ISP, it is found that the data of the built-in EEPROM is completely cleared and reset to 0xFF. After many practices, it can be said that when downloading a program to an AVR microcontroller, the internal EEPROM data will all be reset. Therefore, if you want to burn some initialization values ​​to the EEPROM, the best way is to define a .eeprom segment. After burning the FLASH program, burn the generated eep file to the EEPROM. Modifying Fuse and LockBits does not affect the EEPROM data.

2. If the A/D pin of Tiny5 is floating, the AD voltage of the A/D pin will be affected by the voltage of other pins. Therefore, when using the A/D module, make sure that each A/D pin is not in a floating state. The unused pins can be pulled up or pulled down. This principle is not only for the A/D pin but also for other digital pins. This should be handled without leaving floating pins, reducing potential hazards and reducing EMI.

3. After turning on the LockBits of the AVR MCU, reading the FLASH program and EEPROM data will be FF, but you can re-download the program to FLASH. After downloading the program, LockBits is automatically cleared. The default is off.