1. Overview

BunHMI Display is a Human Machine Interface (HMI) solution by leverage LVGL and combined an onboard GUI processor and memory with touch display.

Also, we provide a free BunMaker software for rapid GUI project development. Let you design the HMI as like as cooking the delicious buns(quick, easy and diverse).

Figure 1. BunMaker GUI Editor

2. BunHMI

There 2 major sockets at the bottom side of BunHMI: UART and TypeC socket. show as Figure 2

BunHMI Back
Figure 2. Bottom side of BunHMI

The TypeC socket is used to download firmware from BunMaker(Figure 1).

The UART socket is used to link with the Host(MCU). There are 4 pins list as below

  • +5V: +5V power supply

  • TX: BunHMI UART Tx signal with logical level 3.3V.

  • TX: BunHMI UART Rx signal with logical level 3.3V.

  • GND: The power GND.

UART default baudrate: 115200, 8n1

The voltage level of BunHMI UART is 3.3V. Which should work fine with 5V TTL interface devices. But not for 5V CMOS devices!
Don’t connect BunHMI with RS-232 interface. This will cause damage of BunHMI display, and not recoverable.

Figure 3 shows typical link diagram of BunHMI and arduino device.

2.1. Boot Mode

There 2 boot mode:

  • Download mode: When plug TypeC cable, BunHMI will enter download mode.You can download firmware by using BunMaker(Figure 1).

  • Normal mode: When plug UART cable and power by +5V, the BunHMI will boot to Normal model and runing the GUI firmware.

2.2. SD Card

There are one SD socket at the bottom of BunHMI. BunHMI is support fat32 filesystem. You can use Buntalk to display image file in SD card, play wav file and read&write string to file of SD card for data log purpose.

Please refer BunTalk for more detail about SD card access.