Open source RK816 power supply

About welding: In order to make the size smaller, we used QFN40 RK816 and Acer QFN32 package 8F2K64. If you don’t have QFN and 0201 or lower welding capabilities, don’t try it. All components of the module are welded with a hot air gun, not to mention that the capacitors of this 0603 are also all Arranged with minimum space. The actual size of the board is 3.6*2.3cm, QFN32 is 4*4mm, and QFN40 is 5*5mm. This version is not the final version. I will wait until all the programs are adjusted before making the board.

Regarding heat dissipation: The module power is about 15W, and the efficiency is still good, so the heat generation is not very large. If you need to add a heat sink, you can directly attach it to the chip after insulating it. The overall height control is very good.

About MCU: The current market situation and this function only use serial port to USB and computer communication, and download and debug. There is also a serial port lead as communication control. It supports all instructions of the serial port except that it cannot download the program. The IIC communication line is used to set the PMIC (RK816 power chip), the SPI-driven LED screen plus a few buttons to set the voltage, plus the RGB-LEDs on both sides of the USB port to indicate the status.

Regarding burning: Download the compiled HEX and burn it into the MCU. Since the burning port is integrated into the USB, the burning program directly uses the type-c cable download. The first time burning program is very troublesome. You need to remove the chip next to the USB socket and fly the wires, and then use USB mode or switch to an external serial port for burning. After burning, the program comes with download detection code, so there is no need to fly wires during later debugging.

About the function: In order to be universal, all commands can theoretically be written into the EEPROM and executed on power-up, including the output voltage and RTC setting time of the module after power-on. All command statuses will have printed information after execution, which can be viewed through the USB-to-serial port, and the baud rate can be set. If external serial port control is used, printing information and commands can be switched to the external serial port.

About time: You can directly use the contents of the computer clipboard to set the time, which can be calibrated in seconds. The built-in RTC clock can automatically compensate for the year, month and day. It is recommended to use it with a battery or an uninterrupted power supply. The error control is average. After all, it is just a PMIC power chip.

function list:

1.RTC, RTC alarm clock

2.USB input/OTG output, choose one from the two

3.DC-DC output, ladder voltage and linear voltage

4.LDO output, ladder voltage

5.GPIO/board temperature/battery temperature, choose one from three

6. Battery charger, can set cell voltage and charging current

7. Battery capacity meter, based on voltage and current

8.ADC function, battery/USB/current/temperature

9.RGB status, configurable

10. Four composite keys, multi-function keys

11.LED screen display, running time, voltage, current, capacity

12. Serial port/USB parameter settings, commands

The above functions are all in the process of being written, and updates are slow and energy is limited.

Welding diagram: The size of the pad and 3D package is estimated wrong. Welding is really a test of skills. I personally don’t recommend messing with it! ! !

Current command: serial port 115200,N,8,1

Attached register description