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Triple M33 low-power portable display

BK7258 is connected to 2x2.16" 480x480 AMOLED, one L1+L5 frequency band GPS module, and one SIM7670G 4G module. And 4 sensors.

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BK7258 is a low-power IoT chip with Arm-V8 Cortex-M33 integrated with 2.4GHz Wifi6+Bluetooch 5.4. It has 3 CPUs, a running frequency of 240MHz+2x480MHz, and built-in 8M Flash+16M Psram. BK7258 can operate LVGL at 480MHz with a working current of up to 9mA. We have connected a GPS/BDS/GLONASS/Galileo/IRNSS/QZSS module in the L1+L5 band and a SIM7670G 4G module compatible with the global frequency band. We have connected the acceleration/gravity sensor, geomagnetic sensor, air pressure sensor, and temperature/humidity sensor for it. Two QSPI interfaces of BK7258 are connected to a 2.16" 480x480 AMOLED display. One display is used to display GPS maps, and the other displays motion information and others. We designed a 1/5" GC2145 DVP camera FPC for it and installed a 6x6MM lens. A MIC and a horn. A 4.35V rechargeable lithium battery interface, 3D printing shell and strap.

BK7258 is an open chip. Its reference documents and SDK can be checked on the official website, but after understanding that its SDK is not very good, I also checked the porting of micropython, although I haven't tested it yet.
https://docs.bekencorp.com/arminodoc/bk_aidk/bk7258/en/v2.0.1
https://docs.bekencorp.com/arminodoc/bk_avdk/bk7258/en/v2.0.1
https://docs.bekencorp.com/arminodoc/bk_idk/bk7258/en/v2.0.1
 
Official website resource download (of course, it can also be downloaded on github):  https://dl.bekencorp.com/
It also has an official forum:  https://armino.bekencorp.com/

  • ​Block diagram of BK7259

    ElecLab • 05/11/2026 at 07:42 • 0 comments

    It is powerful and low-power, capable of driving at least 10.1 "800x1280 MIPI screens, and MIPI CSI and NPU have also been integrated. Preparing to start designing NGFF modules compatible with BK7258 for rapid validation.

  • ​Add three drivers for the transflective LCD screen

    ElecLab • 04/28/2026 at 08:07 • 0 comments

    We tested three types of transflective LCD screens to determine which one consumed less current. Their dimensions, resolutions, and zero-backlight current are as follows:

    3.0" 240x400 RLCD   5mA
    4.0" 272x480 RLCD   10mA
    5.0" 800x480 RLCD   56mA

  • Add driver for Amoled 1.75" 466x466

    ElecLab • 04/28/2026 at 06:46 • 0 comments

    We have found a large-sized round smartwatch display with a resolution of 1.75" 466x466 AMOLED. On its left side is a maximum square display with a resolution of 2.16" 480x480 AMOLED. It boasts excellent display quality and low operating current. The current consumption is 75mA@5V when GPS is enabled. When GPS is turned off, the current consumption drops to 40mA.  Therefore, the total current consumption is CPU + 2x AMOLED = 40mA@5V.

  • Add 2.8" 480x480 and 2.1" 480x480 round LCD screen driver

    ElecLab • 04/24/2026 at 01:08 • 0 comments

    These two round screens are only different in size, and their resolution is exactly the same.

    Simulated aviation instruments and motorcycle instruments use such screens.

  • Add 2.73" 320x320 and 4.0" 480x480 square LCD screen driver

    ElecLab • 04/22/2026 at 04:06 • 0 comments

    Square LCD screens are very common in instruments, especially the 4" 480x480 is widely used in 86 boxes.

  • Preliminary UI elements are designed on the LVGL simulator.

    ElecLab • 04/12/2026 at 04:04 • 0 comments

    The resolution of the whole device is 480x960, which is divided into two 480x480 screens. The first control screen is on the left, and the GPS map display screen is on the right. The display and black screen of the second screen can be controlled separately.

    Since the simulator uses the code of lvgl 9, and the SDK of BK7258 is based on lvgl 8.x, it needs to be properly modified to port.

  • BK7258 RGB PCB is back

    ElecLab • 04/12/2026 at 03:46 • 0 comments

    PCB uses 4 layers of 1mm thickness and 0.3/0.45mm drilling. 

     There are two LCD sockets on the PCB, one is 40P SPI+RGB666+TP. There are many types of this small screen with capacitance touch. Generally, the SPI port needs to be used to initialize the LCD screen chip. 
     The other is an ordinary 40P 4.3" 5" 7" regular TFT screen, which uses a separate 6P TP FPC to connect a capacitive touch screen. 
     Typical screen sizes and resolutions are listed behind the PCB.

  • The camera FPC has been welded after using the steel mesh.

    ElecLab • 04/12/2026 at 03:28 • 0 comments

    6x2.2uF 0201 capacitors and GC2145 BGA chips are very small and need the help of a magnifying glass. 
     The lens holder of 6x6MM is indeed very small, which is limited by the resolution and size of 1/5" sensor, and the area that contains 6 capacitors, which is the best configuration.

  • The new PCB supports RGB interface using BK7258

    ElecLab • 04/08/2026 at 08:47 • 0 comments

    We used BK7258 to design another PCB that supports RGB+SPI+TP and RGB interface displays, which can support displays of a wide range of sizes and resolutions. This PCB removes the 4G module. We marked the list of supported displays on the back of the PCB.

    We chose a 5" 800x480 reflective display as an application with a separate Goodix capacitive touch screen. There is no need to turn on the backlight in the sun, which can save a lot of energy and extend the battery life.

    We tested this display on the T113 EVK as shown in the following figure:

View all 9 project logs

  • 1
    Transfer lvgl from the simulator to the avdk project of BK7258

    We use the BK LVGL simulator, but the code that it generates lvgl is the 9.x version, and we finally used the 8.x version of the nxp simulator again to build the UI. All elements use png files, and finally get a better display effect and low power consumption on 2x amoled. 

     BK7258 works in 240MHz+480MHz dual-core mode, the third core is not enabled, while the two amoled work at 50% brightness, and the GPS module works in L1+L5 mode, their total consumption is 100mA@5V.

    We found a large LCD screen of 6" 480x960 for bicycle applications, and its resolution is equal to the sum of 2x amoled 480x480. The BK7258 has a hardware rotation unit, which can be used for 90-degree rotation of the display without consuming CPU. The application code can run on two displays without adjustment.

    The cover and front shell designed for the 6" 480x960 display have been installed.

    Use BK7258 to connect the 6.2" 480x1280 vertical screen, turn on the Rotation hardware to rotate 90 degrees, and connect the external 7" 1024x600 display, run the lvgl benchmark test program, and there are 50FPS on the 7" display.

    Micropython starts to run on bk7258.

    M.2 B-Key module of BK7258
    The NGFF mod library has added a new member. The BK7258 NGFF module has been designed. We will design a compatible BK7259 next month, which will integrate 480MHz Cortex-M55+480MHz Cortex-M52 MIPI CSI/DSI functionality, as well as a new Cortex-M7 500MHz chip with jpeg/png decoder, arbitrary angle rotator, DMA2D, and built-in 16MBytes 250MHz 16 bit DTR PSRAM.

    We will use it to complete other designs, such as a card style computer with 82Key+4.58 "320x960 LCD touch screen and a 7-inch terminal screen.
    A card computer will have 80+2 buttons, with TCA8418 connecting 80 QWERTY buttons and the other 2 serving as power on/off buttons connected to the MCU. Will use WS2812B LED on the side of the button.

    The shell effect of the first version is shown in the following figure:

    The buttons will be printed with soft silicone buttons for the best feel, but the printing cost is high.

    A new CCM4211 500MHz Cortex-M7 NGFF compatible module is in the PCB production process. The most interesting news is that it can be connected to both QSPI Flash and QSPI Nand Flash externally. BootLoader will directly copy the code from QSPI Nand Flash to PSRAM to run, which means that the MCU's external Flash can start from 128M bytes to 1G bytes.

    After printing the casing, we assembled the LCD and PCB board. The program starts running, and the low-power characteristics continue to be maintained. The current is 11mA@5V When the LCD is removed, the current is 78mA@5V When the screen is running at 50% brightness.

    We upgraded the PCB of the 4.58 "320x960 card computer, using a 4.35V 6000mAh battery, and paired it with an axp2585 PMU chip for maximum 3A fast charging and coulombic meter power measurement. Four sensor chips were placed: six axis/magnetometer/barometer/hygrometer. Silicone buttons are currently in production, using a high-precision process called replication molding. We will try using UV stickers for the characters on the buttons, and it will come back soon.
    There are two B-Key M.2 sockets on the motherboard, one of which is BK7258. Of course, CCM4211 can also be installed and debugged on it now. The other one is a 4G+GPS module.

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