Based on Alibaba Cloud smart devices

Based on Alibaba Cloud smart devices

The schematic diagram is based on Song Gong's schematic diagram, and the PCB design completely follows the design method of the course.

Problems with the schematic diagram:

Above is the schematic diagram I drew.

This is the schematic diagram of Zhou Gong. VCC reaches GND through the U5 chip through the relay coil. The schematic diagram I drew is that both ends are connected to GND. Later it was discovered that the problem had been corrected.

There are several design issues regarding PCB:

1. There is no copper under the relay and wifi module.
2. Strong and weak electricity must be separated
3. After filtering and decoupling capacitors, the circuit must pass through these capacitors before connecting to other devices such as chips. If they are directly connected to other devices, it means that the capacitors have no effect.

Here are the problems that occurred in my PCB design:

The problem is that the C2 capacitor is too far away from the chip. If the capacitor is closer to the chip, the filtering effect will be better. It has been modified later.

The problem with C14 and C15 is that the capacitor is too far away from the U2 chip. The filtering effect will be better if it is closer to the U2 chip. It has been modified later.

Modify the entire line to be thicker and safer. Just double the thickness and don't need to make it too thick. It has been modified later.

Classic mistake, the line passes directly through C11 so that the current does not pass through C7 and C8. C7 and C8 should be put down.

This is the situation after modification, the current passes through C7, C8 to C11.

The above is the problem of pcb and schematic diagram.

Next, wait for the PCB and components to arrive.

This is the printed pcb

Solder stc15 chip and ch304e

The components have basically been welded, because the WiFi module has not yet arrived, and the WiFi module and its smallest system parts have not been welded.