【Solicitation Order】esp32cam_minicar

Project Description

The mini wheat wheel reconnaissance car coincides with the Li Chuang event, and the spare parts in hand can be used to build such a car. For the first time, I experienced the one-stop service of Lichuang EDA->Jialichuang PCB->SMT.

Project function introduction

Control the car to move in all directions through the joystick of the mobile phone app, and have a wide-angle lens to monitor objects and road conditions ahead in real time.

• The main control of the car uses the esp32cam module and an external antenna;

• The IP5306 power management module is used to achieve 2.1A charging and 2.4A discharging. The many features of IP5306 make it very suitable for this car. (Suitable charging and discharging current; esp32cam does not have redundant io driver LED to display power and buttons; the automatic shutdown feature below 70ma is just the trigger for esp32cam to close the camera, without using the IO port, to achieve remote software shutdown, etc.);

• Use two 102535 batteries in parallel (no protection board), 2000mah large battery;

• It adopts type-c interface and supports cc and ac cables.

• Use the design of stacking up and down boards (in such a small design size, one plane cannot fit all the devices. There happens to be a module like esp32cam, so you only need to draw another expansion board);

• Use DRV8833 motor driver chip to drive N20 DC motor;

• The car shell is assembled without screws and buckles, and incorporates some elements of a machine box to prevent disassembly by children;

• The car's integration level is very high. The battery, motor, PCB, and casing are almost all tightly fitted, leaving no extra space.

• • -

Main control module

Because the esp32cam actually has only 7 IO ports that can be used, you need to find a way to get one to control the wheat wheel. You can use io33 occupied by the onboard LED (requires leads), or io4 occupied by the lighting lamp (need to remove a 1k resistor ). The latter is easier to operate, so I chose the latter. The actual location of the resistor that needs to be removed is circled in the picture below. Then change the 0 ohm resistor that controls the antenna. You need to use an external antenna for normal image transmission (I have tried placing the built-in antenna and the external antenna inside the car, but the effect does not work).

expansion board

Lichuang SMT has a very good experience and is ready to use. The female header can actually be SMT, but since we need to solder N20 anyway, we leave the female header for the soldering iron to warm up. N20 needs to be placed on the car chassis and then welded to the M1-4 position on the expansion board.

Charging instructions

Supports cc and ac cable charging, the cc charging current can reach 2a, and the ac current can reach more than 1a. The upper limit of lithium battery charging is 1c, so when using the ip5306 charger, the battery capacity cannot be less than 2000mah. If you want to extend the battery life, you can choose to charge it with an ac cable or a 5v1a charger.

Structural description

The structure diagram is as follows (Mai Lun modeled it lazily, just look at the size), and there is a discrepancy between the camera and the actual picture above. Because there was a mistake in modeling the housing, because the antenna was initially designed to be inside, and an ordinary camera was used, but the effect was found to be poor. So the casing on the camera was cut off directly, so you can barely see it. . . And finally I used a wide-angle lens (on the one hand, the wide-angle viewing angle is large, and on the other hand, the esp32cam’s built-in camera CMOS is vertical. I wanted to take a banner picture, and I happened to have a 120° wide-angle lens, which I tried and it was suitable). The camera cover is to be built as a separate part to adapt to different lenses. My shell proofing business took a long time, and I only had to wait a week this time, so I will wait until the 3D model of the shell is completed later (it will take a long time, because I also want to design a high-looking appearance, this version of the shell There is no decoration, the car light is not actually decoration, it carries 3 functions).

APP description

The app currently uses Blinker (Dian Deng Technology). The advantage is that it is simple to use. Novices can easily reproduce all the content of this project from scratch without relying on apps written by others. The disadvantage is that using the mqtt protocol, the joystick will have a slight delay, but the image transmission will not be affected. I will write an app later when I have time. Of course, if I just want to use it, there are also apps written by others online that can be used (most of them don’t have a joystick).

Precautions

Known PCB issue: The capacitor for the 5V output may be too small. The 5V ripple is a bit large when the motor starts. Because the logic 3.3v passes through an ldo, it can be used normally (as long as it is not measured with an oscilloscope, this problem does not exist). The advantage of the motor using 5v voltage instead of 1s voltage is that it can The disadvantage of software controlling the consistency of the motor without an encoder (very important for the wheel) is that it will interfere with the stability of the 5V voltage. The capacitors I have chosen so far are relatively small. Changing them to larger ones should improve the ripple.