Embedded software and hardware debugging problems

1. Serial numbers cannot be sent and received continuously during RS485 usage.

At first, the problem was that the TX of maxcompute needs to be connected to the pulling resistance, and 20 K of the large resistance cannot be used. Using a strong pulling resistance of less than 10 can solve the problem.

Later I found the problem. When the number of 0 s exceeds 10, I found that the problem was caused by the high common mode voltage. I handled the two 485 S and solved the problem.

2. ZigBee module problems.

During the last debugging, it was found that a module had to be powered by a downloader before it could work, during the final debugging, it was found that the reset end of a module had a problem and was always in the reset status. Therefore, the reset end could not be run and was directly connected to the power supply.

3. lm331

VFC, voltage frequency conversion.

4. today, I used my own design of the CPLD-driven 4.3-inch TFT with a TF card seat attached to it. After a night's initialization failed, I finally found that after the backlight is turned on, the power supply voltage of 3.3v is reduced to about 3.0v, leading to abnormal TF card operation.

5. the MA recoverable insurance is used to supply power to the stm32. It is found that the baseline source has a great power float, and the 3.3v power supply is also fluctuating. This problem can be solved by connecting the recoverable insurance to 0 euro resistance.

6. When no isolation module is used for RS485, it is best to share the ground. If isolation is used, there is no need to share the ground, and sometimes it will cause great noise interference.