display issues on new m5-Stick C hardware

[wilberforce]

Build environment: Windows Target device: new m5-Stick C

Description Getting display smudging on the new hardware. Works ok on the older hardware. Photo to follow

Steps to Reproduce Interestingly the sample: https://github.com/Moddable-OpenSource/moddable/tree/public/examples/drivers/m5stickc-imu works fine.

The app I'm building uses both BLU and WIFI.

This seems to be related to changes in the last 3 weeks - I've not been able to narrow it down yet.

Expected behavior Both old and new hardware to display cleanly.

Images upper unit: new hardware (MPU6886)

lower unit: old hardware (SH200Q)

[phoddie]

@wilberforce, that's an artifact I'm not sure I could generate in software (at least not easily!). I'm going to guess this is a hardware configuration problem. (I don't have an M5 Stick, so I can only guess)

The recent addition of support for M5Stack CORE2 included changes to the driver code for the AXP192 power management chip. I believe that chip controls power to the display. The AXP192 code was reorganized to put the device specific code into setup-target.js. Maybe you can review those changes?

It is curious that you don't see a problem with the IMU ball example. That might be because it has a 25% gray background color, which is much less bright than your project's white background.

@meganetaaan seems to understand the AXP192. Maybe he can help?

[wilberforce]

@phoddie

The recent addition of support for M5Stack CORE2 included changes to the driver code for the AXP192 power management chip Thanks for the direction - I'll roll this back and see if this makes a difference.

It is curious that you don't see a problem with the IMU ball example. That might be because it has a 25% gray background color Another area to try - the problem still exists with the brightness so between 7-15. I'll try the actual background colour too.

Thanks for the hints - exactly was I was after!

https://github.com/Moddable-OpenSource/moddable/commit/96f7a42820e9b49a5afce0512bee98f458b03f31#diff-4693061397f7cc50ec6f13276d947f3f

[wilberforce]

@phoddie @meganetaaan

I've got to the bottom of it - it's when I call the brightness setter.

I'm passing the value 10, so it's writing to 0x28 with the value 160.

brightness=10;
global.power.brightness = brightness;

https://github.com/Moddable-OpenSource/moddable/blob/public/build/devices/esp32/targets/m5stick_c/setup-target.js#L139-L142

As soon as this happens, the display smudges...

[phoddie]

Cool!

FWIW - Tthe range of brightness should be 0 to 100. That's what the backlight control on Moddable Two uses:

https://github.com/Moddable-OpenSource/moddable/blob/ece6a84f3190d1191bf4698c656aad0755d6d5e3/build/devices/esp32/targets/moddable_two/setup-target.js#L12-L19

So the 10 you are passing is valid. I guess the question that needs to be sorted out is the range of the power register at 0x28.

[wilberforce]

Existing:

set brightness(brightness) {
    const b = (brightness & 0x0f) << 4;
    this.writeByte(0x28, b);
  }

https://github.com/m5stack/M5StickC/blob/master/src/AXP192.cpp#L155-L163

uint8_t buf = Read8bit( 0x28 );
    Write1Byte( 0x28 , ((buf & 0x0f) | (brightness << 4)) );

[phoddie]

Thanks for the reference to the M5StickC code. The complete function is helpful

As you noted above, the low nibble of the register is getting overwritten. But, the range is 0 to 12 is important too. It is 0 to 12, so we should map the 0 to 100 input. Something like this?

set brightness(value) {
    if (value <= 0)
        value = 0;
    else if (value >= 100)
        value = 12;
    else
        value = (value / 100) * 12;
    this.writeByte(0x28, (this.readByte(0x28) & 0x0F) | (value << 4));
}

[meganetaaan]

Sorry to be late! I didn't know that so many has been updated on the original repos since my first PR for adding M5StickC target.

• The change of brightness setter is one of them. But I wonder why current original sets 12 as upper limit. I remember valid register value is between 7 and 15 when I made my commit. Once you try setting 0-6 you will know it leads the same as dark as 7. Below worked for me.

  set brightness(value) {
      if (value <= 0)
          value = 7;
      else if (value >= 100)
          value = 15;
      else
          value = (value / 100) * 8 + 7;
      this.writeByte(0x28, (this.readByte(0x28) & 0x0F) | (value << 4));
  }

• FWIW I've noticed the initialization sequence also has been changed a lot. Current code could have another issue about compatibility of old and new hardware. But unfortunately I cannot confirm them because I don't have new one :(

[wilberforce]

@meganetaaan

Thanks for looking at this.

I agree with the 12 vs 15 thing - unless it was deemed > 12 was too bright and drawing too much current? I'll give it a go.

As far as startup sequence goes- rather than Writing directly to registers - are we better off using your classes in AXP192. This way in the manifest we could define what get intialised?

The other thing I have been considering is this: https://github.com/m5stack/M5StickC/blob/master/examples/Advanced/AXP192/BtnIrq/BtnIrq.ino

This allows the power on/off button to be used as a normal button - the press causes an IRQ (on pin 35) and then you poll the button.

This means we could have buttons A, B and C. I was thinking of using these a select. up and down for a menu system.

Also the stuff for wake-up on movement could be useful too.

[wilberforce]

@meganetaaan

That change works fine. I'll do a pull request