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Author Topic: BT816 NOT START ALL THE TIMES- WHITE SCREEN  (Read 240 times)

SANDU ONICA

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BT816 NOT START ALL THE TIMES- WHITE SCREEN
« on: September 08, 2020, 07:16:16 PM »

HELLO,
I used in the past FT800 and I had not problem with this.
BT 816 don't start all the times, sometimes it start with white screen, I checked, for example in this situation PWM control working .
I tried with CPU RESET,COLDSTART,ETC.BT 816 ARE BLOCKED.
Where is the problem?

Best regard,

Sandu Onica
« Last Edit: September 08, 2020, 07:27:24 PM by SANDU ONICA »
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BRT Community

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #1 on: September 09, 2020, 04:48:14 PM »

Hello,

Please ensure you follow the recommended start-up in the Programmers guide below (see section 2.4).

https://brtchip.com/wp-content/uploads/Support/Documentation/Programming_Guides/ICs/EVE/BRT_AN_033_BT81X_Series_Programming_Guide.pdf

When you read the REG_ID do you get 0x7C correctly and when you read REG_CPURESET do you get 0?

Best Regards, BRT Community


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SANDU ONICA

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #2 on: September 09, 2020, 07:26:00 PM »

HELLO!

When start corectly ,ofcourse  this registers are tested.
It's posible when are blocked ,this registers have another values?
Power regulator start different for BT816.
This regulator run in Power Down state, for FT800  are disabled and can be restart software.
I"m afraid that power regulator it's problem.
I used RIVERDI 3,5 " .

Best regards,

Sandu Onica
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SANDU ONICA

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #3 on: September 09, 2020, 07:50:06 PM »

4.9.3.4 POWERDOWN state
In POWERDOWN state, the clock oscillator, the PLL and the system clock applied to the BT815/6 core is disabled. The core engines are powered down while the SPI interface for host commands remains functional. All register contents are lost and reset to default when the chip is next switched on. The internal regulator remains on.


I POSTED FROM   BT81X (815/6) Advanced Embedded Video Engine Datasheet
Version 1.0

Best regards,

SANDU ONICA


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BRT Community

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #4 on: September 11, 2020, 05:20:44 PM »

Hello,

It is possible that REG_CPURESET may not be 0 if the chip has not fully initialised.

If you assert and then deassert the PD line before the start-up sequence, it should reset the chip. Any change in the clock (CLK commands) should be done before the active command as these pout the device to sleep and the active (and the following delay of 300ms) must come after the clock commands.

When it fails to start, how far do you get through the recommended start-up process from section 2.4 of the programmers guide. did the REG_ID read 7C and the REG_CPURESET read 0?

Also, do you have all the new definitions for the registers of the BT816?

Best Regards,
BRT Community
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SANDU ONICA

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #5 on: September 11, 2020, 05:36:40 PM »

Hello,
Thank you for your advice.
I don't understand why 1 from 10 start up the touchscreen fails and another 9 times working good.

Best regards,

Sandu Onica


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Rudolph

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #6 on: September 12, 2020, 04:52:23 PM »

I am not sure what the actual issue is.
Well, okay, I get that you see the BT816 not starting reliably.
However, you also claim that you were using the FT800 and never had this issue.

The difference between FT80x and FT81x and beyond in regards of power down is that
you have to use the Power Down line with FT80x to wake it up.
And with FT81x and beyond it is possible to get from POWER DOWN state to ACTIVE state by SPI if EVE was brought
into POWER DOWN state by SPI and the PD_N pin is also high.

The price that you can wake up FT81x+ via SPI is a much higher "Power Down Current" since that internal voltage regulator can not be turned off.
That is not the issue, this is a feature and the remaining 0.2mA could be saved by switching off the power supply.

So your function to start a FT800 that you not had a problem with should be doing just fine starting a BT816.

My code always used the PD_N pin as a first measure in my EVE_init() und it is doing just fine with all EVEs.
Only for the case that the PD_N pin would not be connected for some reason I have this line in my EVE_init():
/* EVE_cmdWrite(EVE_CORERST,0); */ /* reset, only required for warm-start if PowerDown line is not used */

And I have it commented out since all my hardware connects the PD_N pin.


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SANDU ONICA

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Re: BT816 NOT START ALL THE TIMES- WHITE SCREEN
« Reply #7 on: September 14, 2020, 05:39:51 PM »

Hello,

I succeeded, BT 816 START without problems.
I activated PWM DISPLAY, PCLK and GPIO after writing the first display list.
Now everything is OK, thanks for everything.

Best regards,


Sandu Onica
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