High speed drawing with ESP32-WORVER and CPLD
In the previous experiment, by using ESP32-WORVER for the microcomputer, the memory can be increased and a lot of image data can be held, and the CPLD can be used to directly generate the control signal for the electronic paper from the SPI signal. By doing, I found that drawing can be done at high speed like animation.
Since the experiment went well, I'd like to turn this experimental board into a PCB.
Design with KiCad
These are the circuits around the microcontroller of ESP32-WROVER. I used the ESP32-WROVER-DEVKIT circuit as a reference.
As for the USB connector, I tried USB-C for the first time this time. Hopefully, I'll try to design in USB-C from now on.
It is a circuit around the MAX V CPLD, which is indispensable for speeding up drawing. However, the circuit is very simple and consists of just a CPLD, JTAG, and an electronic paper connector.
Power supply for EDP
The circuitry is the same as the reference design of the dedicated power supply IC for electronic paper. This power supply IC is controlled by I2C. The WAKEUP signal is pulled up high so that I2C signals can be accepted.
I tried to make this PCB large enough to fit the board completely on the back side of the electronic paper.
Since this is an experimental PCB, I made it possible to output the empty pins of ESP32 and CPLD to the pin header so that it can be extended later. SPI and I2C are also output to the pin header in the same way.
The booklet that came with the transistor technology is very useful to use KiCad like a manual.
May be hard to mount
This time, there are two 0.4mm pitch ICs on this board, and there is also a 0.5mm pitch connector. If everything is not mounted well, it won't work. It's going to be a bit difficult to mount. For the other parts, I used the 0603 size, which should be fine.
I would like to put it together with the other PCB and order it from a PCB manufacturer in China.
2020.5.31 Add The PCB was received and the components were mounted.
End of addition