Considering that color silk screen printing is copyrighted and some people resell it and use it commercially, I no longer provide complete patterns. I only provide background boards without copyright or complete patterns filled with watermarks. If you need color silk screen printing, you have to find the picture yourself and put it together. Enter the PCB, or you can find the corresponding copyright-owned artist or company for authorization, submit an authorized screenshot to me, and you can provide the original image source file.

B station video: https://www.bilibili.com/video/BV1FG4y1s7tZ/

0.0 Development Board Preface

Some time ago, LC also rolled out a lot of development boards, how could I not be outdone! (It seems like that’s the opposite!)

Hence the Jerry development board.

0.1 Preface to Jerry’s (domestic) chip ( I hope you can read it )

There are many foreign manufacturers of Bluetooth chips, and those that make Bluetooth A2DP (that is, capable of Bluetooth audio transmission) are: TI, ST, Qualcomm, NXP, Cypress, etc.

There are also many domestic manufacturers of Bluetooth A2DP chips, such as Momentix, Jerry, Zhongke Lanxun, Anxinke, Shanjing, Hengxuan, etc.

However, there are very few domestic manufacturers that can open source their data and documents. Basically, the only ones who can get the data are foreign Bluetooth manufacturers. In the past few years, the only domestic manufacturers seemed to be Anxinke (ESP32).

As we all know, domestic Bluetooth chip manufacturers rarely release information to individuals. Even if they have information on hand, they rarely share it.

However, due to various factors such as the huge increase in chip prices in the post-epidemic era, we have to choose to transform into domestic chips. Therefore, many manufacturers have gradually begun to open source their various Bluetooth chips, which also facilitates the cultivation of a group of enthusiasts.

In China, there are Shanghai Broadcom's BK7252, Zhongke Lanxun's AB32VG1, Boliu Intelligent's BL606P (should not have A2DP), and the Jerry AC79XX series in this project.

Off topic:

Before the launch of the 79 series, most of Jerry's chips were closed source . Most of the Jerry chips that you can buy on Taobao are agents , and the software that works is specially customized (public version software )

For example, in this case, the software has been hard-coded , and you can only control it through IO, or better yet, through the serial port.

In other words, you can use it after you buy it and plug it in. You can’t customize it or burn the code yourself, and burning the code requires a special download tool. There used to be hundreds of these download tools.

What's more, SDK is very difficult to get. Even if you get SDK, Jerry compilation tools still need to apply for LICENSE from Jerry official, one machine, one code.

Moreover, for chips purchased by an agent, you also need to write the key provided by your purchasing agent in the code...

This series of operations caused previous individual developers to encounter trouble in the first step when they wanted to use Jerry's chips!

But now, my lord! Times have changed, Jerry 79 series are all open source!

1. Introduction

This development board is modified based on Jerry's official development board: JL_AC79_DevKit V1.0

The development board contains a core board and a base board, which are connected using pin headers.

The basic schematic diagram of the core board is basically copied from the official one, except that the wiring and antenna are different.

The camera and screen module of the official base board are removed from the base board, IOKEY is added, the power amplifier is replaced with a 4.5wx 2 boost amplifier, serial port circuit and battery management chip, built-in lithium battery, and an IIS to analog audio circuit is added.

The picture below is the core board:

There is also a white version:

The picture below is the core board + color screen printing bottom board:

Official development documents:

https://doc.zh-jieli.com/AC79/zh-cn/release_v1.0.3/board_description/board_overview/index.html

Official schematic:

https://gitee.com/Jieli-Tech/fw-AC79_AIoT_SDK/tree/release/AC79NN_SDK_V1.0.3/doc/datasheet/AC791N%E8%A7%84%E6%A0%BC%E4%B9%A6/schematic/JL_AC79_DevKitBoard

The FLASH welded on my development board is 16M Byte.

Official development version purchase link: https://item.taobao.com/item.htm?spm=a1z10.1-c-s.w4004-22883854875.30.504d246b7hM503&id=668602916268&mt=

It's just that the official board is a bit more expensive, so I made one myself.

A set costs 500.

1.1 General framework

The general framework is as follows, which is similar to the official one, but with some changes:

2.0 Core board part

This part mainly introduces the core board resources and how to burn and run the simplest DEMO.

2.1 Core board system block diagram

2.2 Core board IO

The IO here is an official picture. In fact, the functions of an IO are far more than what is written above. For details, you can check the chip specification sheet.

2.3 Development environment

Official Documents Section 3

https://doc.zh-jieli.com/AC79/zh-cn/release_v1.0.3/getting_started/environmental_install/index.html

Download and install CodeBlocks, install the toolchain, and install the package manager.

Can be compiled using VSCode.

2.4.HELLO DEMO

Run the simplest HELLO DEMO and view the serial port output

Now modify the correct FLASH capacity in app_config.h in the include folder.

The official default is 8Mbit. I used 16Mbit, so I changed it to 16. The SDRAM capacity in AC7916A is 8Mbit (4M*16bit), so it also needs to be modified.

Looking at the code, we can see that the C0 pin is the TX port.

Then enter the download mode and compile and burn the code.

For specific operations, please refer to Section 4.2 of Jerry's official guide:

https://doc.zh-jieli.com/AC79/zh-cn/release_v1.0.3/getting_started/project_download/download.html

2.5. Additional instructions

The main control of this core board is AC7916A, which is an external FLASH, so no upgrade tools are required. For Jerry main controllers with built-in FLASH, such as AC7915B6A, AC7911B8, and AC7913A6, you need to purchase the Jerry forced upgrade tool:

You cannot do this tool by yourself, you must buy it, there is a transmission protocol in it.

Purchase link: https://item.taobao.com/item.htm?spm=a1z10.1-c-s.w4004-22883854875.2.4130246byY0LU9&id=620295020803

3.0 Base plate part

This part mainly introduces the various resources and verification of the baseboard.

Function verification mainly uses the official wifi_story_machine DEMO.

Mainly modify the board_config.h macro definition to achieve the function.

The directory: fw-AC79_AIoT_SDK-release-AC79NN_SDK_V1.0.3\apps\wifi_story_machine\board\wl82

The chip and development board macros are defined as:

Please ensure consistency.

3.1 Introduction to baseboard resources

The block diagram is shown on the core board, but not here. Let's look at it from the PCB.

There are actually quite a lot of resources, including battery power management, serial port, USB, LINE IN, OLED, microphone, IOKEY, ADKEY, SD card, LINEOUT, AMP, DAC, and various jumpers.

In the middle is a direct-plugged core board, and all IOs are directed to the bottom board.

3.2 Backplane power management

The charging management uses a TP5100 that I have used frequently recently. It can charge a single lithium battery at 2A, or two strings of lithium batteries. It uses a TYPE-C 6PIN power supply. The power supply comes from the battery and goes directly to the switch.

The 3.3V of the backplane is the same as that of the core board. It also uses the same DCDC. There are reserved jumpers. You can select the PA0 port controlled by the MCU or enable it directly.

In addition, there is a battery boosted to 5V for USB power supply, and there is also an MCU-controlled PC9, which can also be directly enabled.

3.3 Baseboard KEY

The buttons are divided into IOKEY and ADKEY. The official DEMO mainly uses ADKEY.

IOKEY uses PC4, PC5, PC6.

3.4 Baseboard LED

There are a lot of LED lights reserved, one main power supply is 3.3V LED, the other LEDs are connected to the PC port, and can be lit using IO or PWM.

3.5 Baseboard DEBUG

DEBUG uses the CH340C USB to serial port chip.

The default DEBUG port is PB3.

Please make sure that the macro definition has PB3 turned on:

3.6 Baseboard amplifier

The power amplifier uses XA9521.

It is a 2×4.5W/3.7V, adaptive boost, ultra-low EMI, high signal-to-noise ratio, Class G two-channel audio power amplifier.

The chip integrates a multi-channel power rail adaptive boost unit. When powered by a 3.7V lithium battery, it can drive a dual-channel 4Ω load to output 2×4.5W constant power.

Reserved power amplifier mode selection jumper.

The power amplifier is relatively unpopular, and I may use a more easily available power amplifier in the future.

3.7 Backplane SD card

The SD card is connected to the PB5, PB6, and PB7 ports, single line, and the power supply can be selected.

In the macro definition, you need to modify the SD card to group A of SD0, that is, PB5, PB6, and PB7.

CLK detection, single-wire mode.

3.8 Backplane digital-to-analog conversion

IIS to analog audio signal.

Use 4344 chip.

3.9 Backplane USB

USB pass-through to MCU, USB5V powered by boost.

3.10 Baseboard OLED screen

OLED controlled by IIC, connected to IIC PH0 PH1 port.

3.11 Floor microphone

Use a silicon microphone, connect it to the MIC IN of the MCU, and separate AGND.

4.0 Advanced features

There are many advanced functions that you have never played before, you can try them out.

4.1EQ

Open Jerry package.

Choose this for the AC791X series. If it is different for the AC790X series, please refer to the official development documentation for details.

Use wifi story machine demo.

Turn on EQ, online EQ, and USB communication in app_config.h

After the USB is burned in, do not disconnect the USB and open the serial port.

After opening it, you will enter the EQ adjustment map.

You can choose musicEQ for adjustment.

There are 10 sections of curve EQ that can be adjusted.

After adjustment, you can listen to the effect online. After adjustment, click this button to save it. The sound effect will continue to be used the next time you turn on the computer.

EQ is only for Bluetooth. If you want EQ effect in other modes, remember to add EQ code under each mode decoding.

For example, add the following enabling code under LINEIN.

This code can be found in BT decoding code.

Finally: color screen printing on the base plate.

Choose a pink Pokémon theme, which is basically pink Pokémon.

Import into PS for typesetting.

To be continued, the functions of the development board will continue to be improved.

Currently known issues:

1. The 7th pin SDB of the XA9521 power amplifier should be selected with the SDA pin.

2.The resistance of SD card detection pin and CLK pin should be changed to 7.5K.

3. The AUX socket LR is reversed. If the LINEIN mode is used, the left and right sides of the amplifier will be reversed, but the LINEOUT will not be reversed.

B station video：https://www.bilibili.com/video/BV1FG4y1s7tZ/

Video demonstration: