Exterior

The PCB acrylic shell is in the project file, but it is not recommended (it is expensive). I made it together with the robotic arm in the first version, but it was too thin, so I simply made a new robotic arm (3mm) in Moubao.

The clip for holding the marker (sort of) has a diameter of 12.2mm. A 12mm or slightly larger marker should be able to fit in just fine. I attached it with hot melt glue.

There is a problem

• Acrylic is too thin. Before I bought it, I thought it would be okay to be thinner (I bought 1.5mm, which required 3mm, which was half the size). I bought it a long time ago, but I have been learning the software and have not installed it. The last one It was only after I started working together that I discovered that the acrylic broke if I applied too much force. Ah! My life is given by hot melt glue, hot melt glue yyds! Too thin also leads to incorrect installation position, mismatched screw lengths, and overall looseness! It’s the same reason in the video! (Resolved, July 20, 2022)
• I changed to a marker pen, but it is not erasable (can only be wiped with alcohol), so I still have to buy a marker pen... My wallet~, it should be better to buy the kind that is harder to dry, and the ink pen.
• There is also a problem with the pen wipe point.
• The automatic clock can only be realized through the host computer, and you will learn how to go offline later.

Learning experience

I feel like I still need to record it, and I’ve been watching the video step by step.

Lichuang eda video link collection: https://space.bilibili.com/430536057/channel/collectiondetail?sid=232449

But when I looked at it , I was confused in Python. How could he move? After reading it, I realized that I should read the firmware code first, and then Python (I didn't watch the live broadcast, and I don't know if it was a problem with the upload order). My first reaction was to read it in order.

Firmware is a large piece of code. We build another platform on the Hongmeng platform, and then break away from the C language level and use simpler Python to write it. For example, the AT command set of commonly used Bluetooth and wifi is also a firmware. This has recently been There is an explanation in the Q&A video (at 45 minutes).

Q&A video: https://www.bilibili.com/video/BV1yr4y1u7fn?spm_id_from=333.999.0.0&vd_source=f87e51689044981647f4f4464ea1e304

other

When burning, the power supply used is 3V3, and the voltage will be output from the input terminal through the LDO (only about 2.78V). This should be caused by the current flowing back through the internal MOS body diode. There is no problem in the first place, the voltage is not high, and the current is not large. , the LDO will not be damaged, but the power indicator light will flash... Use an oscilloscope to test and find the pulse signal at the LDO input end.

Demo video

1. Draw a circle (but not very round)
2. Draw a five-pointed star
3. Automatic clock (because markers are quick-drying and need to be wiped with alcohol every time, so I will demonstrate it here)