【Solicitation Order】ESP32-C3 VDF Clock

### Project Introduction

The display effect of the VFD screen is quite eye-catching, I like it very much.

When I have time, I go to the seafood market to see if there are any VFD screens with good designs and cheaper prices. At the end of November, I opened the seafood market and promoted this screen. "15￥10 pieces, 25￥20 pieces" Good guy! It was so cheap that I decisively placed an order for 20 pieces, which cost 37 yuan including postage.

Then a group friend told me about Lichuang’s activity for using Essence modules. At first glance, I could get a 50-yuan component coupon for free. My DNA moved. Even though I had never used ESP32, I signed up.

In half a month, I was in a hurry. I measured the pins corresponding to the segments and bits of the screen and tried the supply voltage and current of the screen. I barely used ESP32 and wrote the VFD driver chip driver.

Another group member said that there are several companies making this screen, and the number of pins used and screen content are somewhat different. Some are called DL18-0615, some are called VFD18-0615


, and then this cheap screen was sold out by others... ..................

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### Project function introduction

* Simple time display;
* Turn off the VFD screen at a fixed period (not available yet);
* Countdown reminder ( Pay attention to rest your eyes, it is not available yet);
* WIFI time adjustment (it is not available yet);

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###

In the project properties, you can fill in the completion progress bar of the project, and select the check box according to the completed functions. It can also be used to display the progress of function completion

* [x] Schematic design
* [x] PCB design
* [x] PCB proofing
* [x] Welding test
* [ ] Functional test
* [ ] Program test
* [ ] Supplement When calibrating online
* [ ]

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The holes on the assembly board are M2 specifications, and M2 copper pillars can be used

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### The circuit is explained and

designed with 2 PCBs, separating the VFD driver board and main control board, VFD The driver board can be used to control other microcontrollers.

The VFD screen test section and pins are quite bright when using an anode grid voltage of 12V. When using the VFD driver chip to dynamically scan, the brightness needs to be around 28V to be satisfactory, and the filament provides a voltage of around 2.5V.

At first I wanted to use a positive voltage driver (29V for the anode grid and 2.5V for the filament), but the HV5812 I was using only had 20 output pins. The screen I had needed a driver chip with 21 output pins, so I had no choice but to change it to negative. Voltage drive (anode grid 0V, filament -26.5V).

The negative high voltage is realized by using XL6007E1 boost + charge pump. The filament uses a bias circuit and LM9022 to realize AC drive (the brightness of the two ends of the AC filament screen using DC is not uniform, and the end with a lower voltage is darker).

The VFD driver selected HT16512.

Because the main controller had to use Essence's ESP module to participate in the event, he used the ESP32-C3S-2M he had on hand.

The RTC chip uses PCF8563T.

The 3.3V power supply supplies the ESP32 module, CH340C, and HT16512. It does not require a large current, so it is enough to choose AMS1117.

5V power supply is used to boost the negative voltage and drive the filament.

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### As for the software

```C
program, let’s talk about the HT16512 driver. It is not easy to edit the open source project. The details will be posted on the B site and then linked.``
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### Update record

2021-12 -22: The IIC pull-up resistor was pulled to D4, which caused the CR1220 to power off abnormally. It was quickly fixed. The MBR0530 of D4 and D6 was replaced with 1N4148W T4 to reduce the reverse leakage current. Currently, the power supply current of CR1220 to PCF8563 is about 0.57uA in the power down state. .

2022-01-20: The XL6007 boost was replaced by LM2611AMF with soft start, and the VFD screen power supply control was brought together with DCDC.

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### Actual pictures![ESP32-C3-VFD02.jpg]
# Demonstration video