GC9A01 LCD with IMU not working together...please assist

Products & Technology XIAO
#1

Hi,
I have got a GC9A01 Round LCD display working with the GFX Library for Arduino on my Xiao BLE Sense. On a separate sketch, I have also got the IMU working using the Seed Arduino LSM6DS3, HighLevelExample. However, when I combine them, it compiles and uploads fine. However, it just gets stuck and nothing shows up on the display.

The problem occurs when I use myIMU.begin() with gfx->begin() at the same time. Turning one or the other off allows the other to work again.

After poking around, I found that if I change LSM6DS3 myIMU(I2C_MODE, 0x6A) to LSM6DS3 myIMU(SPI_MODE, 0x6A) the display and the unit runs again. However, when I use myIMU.readFloatAccelX(), it just gives me a static value of 1.87.

I should mention that I’m not using default pins for the GCA01, my setup is
Arduino_DataBus *bus = new Arduino_NRFXSPI(3 /DC/,2/CS/,5/SCK/,4/MOSI/,12/MISO/);
Arduino_GFX * gfx = new Arduino_GC9A01(bus, 1/DF_GFX_RST/,0/rotation/,true/IPS/);
Also, I’m powering the GCA01 from Xiao’s 3.3V pin.
I should also mention I’m very new to this, all this stuff.

Please help.
Thank you in advance.

#2

So as I was poking around a little more I discovered some more details.
Suppose I call gfx->begin(); I can draw on the screen fine. But if I then call myIMU.begin() afterwards, the code that actually halts the program is the first instance of Wire.endTransmission() in the LSM6DS3Core::readRegister found in LSM6DS3.cpp. I also noticed when TARGET_SEED_XIAO_NRF52840_SENSE it defines Wire as Wire1. I wonder why Wire1 endTransmission is clashing with the gfx…

Now doing this the other way around. Suppose I run myIMU.begin() first, the program halts when I call any particular gfx draw function e.g. gfx->drawRect(…). Other non-draw functions are fine. The code that halts it is the first instance of writeAddrWindow(…) found in Arduino_GC9A01.cpp, Which calls _bus->writeC8D16D16(…) from Arudino_NRFXSPI.cpp in my case. In conclusion, writing to the display while Wire1 is ending transmission seems to be the problem. I just don’t have enough knowledge to determine why that is the case…

#3

SOME SUCCESS! So I ordered an ST7789 1.3" Display and I tried the same thing with the same libraries, GFX_Library_for_Arduino and Seeed Arduino LSM6DS3. This time around I just connected to the display to the board SPI defaults e.g. MOSI 10 and SCLK 8. Again on different sketches, it works fine, but together it hangs. So I tried a new display library.

Finally, the display and the IMU worked together. Either the GFX_Library_for_Arduino library is incompatible or I’m not setting it up right.

I still need to get the GC9A01 Display working with the IMU as that is my preferred display though.

#4

Solved. After some intensive research, I did the following

  1. Used the following library
    GitHub - PaintYourDragon/Adafruit_GC9A01A: Adafruit_GFX-compatible library for GC9A01A display driver

  2. I also added to the Seeed Arduino LSM6DS3 library.
    #include “pins_arduino.h”

then proceed to add the following before a wire.endTransmission call

if (digitalRead(I2C_SCL1)) == LOW || digitalRead(I2C_SDA1))
{
break;
}

I read that it helps to avoid hangs in the wire library. Not the most elegant solution but the GC9A01 LCD now works with the IMU.

#5

Thanks for spending our time in sharing the updates. Will be helpful for many.

#6

Hi, I have get the same issue with the Arduino GFX library using the Seeed Xiao BLE Sense nrf52840 board at Arduino IDE. You need use the Arduino_mbedSPI class at the bus declaration like: Arduino_DataBus bus = new Arduino_mbedSPI(6 / DC /, 7 / CS */). This work for me.