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Author Topic: Migrate from ft811 to bt815  (Read 846 times)

FlorianG

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Migrate from ft811 to bt815
« on: August 08, 2019, 10:35:51 AM »

Hello,

I made myself a custom BT815 card and I can not make it work.
I do not know if it's the hardware or the software that does not work properly.

Regarding the hardware I base myself on the ft81x library.
I use the same screen with my ft811 but nothing happens. the slab of the screen is lit in black but nothing else. Backlight does not light.

I have not stopped rereading the Programmers Guide of ft81x and bt81x but I do not see what needs to change to set, start and turn on the screen in white.

Can you confirm that nothing changes for basic setup and parametrage instructions.

thank you very much in advance
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Re: Migrate from ft811 to bt815
« Reply #1 on: August 08, 2019, 01:28:25 PM »

Hello,

We have successfully tested the following library with the BT815 IC in the office here:
https://brtchip.com/wp-content/uploads/Support/Documentation/Application_Notes/ICs/EVE/BRT_AN_014_FT81X_Simple_PIC_Library_Examples.pdf

Now it doesn't include the definitions or implementations of BT81X specific functions, but it should allow you to get up and running as the SPI and legacy FT81x functions remains the same for the BT81x. The code included is based on a PIC microcontroller, but it shouldn't be too hard to port to your given MCU (you basically just need to do the SPI implementation for your MCU).

If you wish a schematic review please email in to us at:
support.emea@brtchip.com

Best Regards,
BRT Community
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FlorianG

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Re: Migrate from ft811 to bt815
« Reply #2 on: August 13, 2019, 11:38:23 PM »

Thank you for your reply.

I use a teensy board for the CPU here.

if you inform me that the basic boot order is the same so my problem has to be in the hardware.

here are the diagrams of my prototype.
Will be very grateful if you took the time to see if all is well. I have already checked many times but it did not give anything
In the meantime I will check that I have correctly made my prototype
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Re: Migrate from ft811 to bt815
« Reply #3 on: August 14, 2019, 11:37:47 AM »

Hello,

I cannot see anything inherently wrong with your schematic.

I would suggest checking that all the power supplies are correct and ensuring there are no shorts on your board.

Best Regards,
BRT Community
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FlorianG

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Re: Migrate from ft811 to bt815
« Reply #4 on: September 03, 2019, 12:04:00 AM »

Hi,

I progress in my project but I hit a problem I can not solve.

I use teensy 3.6 and VM816C50A-N
https://fr.farnell.com/bridgetek/vm816c50a-n/type-carte-credit-moteur-video/dp/2931597

When initializing the BT816, I can not display other images than this image.

Here is my code. At this point the bus spi works at 30 Mhz :

    GDTR.hostcmd(0x68);
    GDTR.hostcmd(0x44);
    GDTR.hostcmd(0x61);
    GDTR.hostcmd(0x62);
      
    GDTR.hostcmd(0x00);
    delay(300);
   
    GDTR.wr32(/*REG_FREQUENCY*/0x30200C, 60000000 );
   
    GDTR.wr32(/*REG_HCYCLE*/0x30202C, 1056);

    GDTR.wr32(/*REG_HOFFSET*/0x302030, 46);   
    GDTR.wr32(/*REG_HSIZE*/0x302034, 800);
    GDTR.wr32(/*REG_HSYNC0*/0x302038, 0);
    GDTR.wr32(/*REG_HSYNC1*/0x30203C, 10);     
    GDTR.wr32(/*REG_VCYCLE*/0x302040, 525);   
    GDTR.wr32(/*REG_VOFFSET*/0x302044, 23);     
    GDTR.wr32(/*REG_VSIZE*/0x302048, 480);
    GDTR.wr32(/*REG_VSYNC0*/0x30204c, 0);
    GDTR.wr32(/*REG_VSYNC1*/0x302050, 10);
   
    GDTR.wr32(/*REG_PCLK_POL*/0x30206C, 1);
    GDTR.wr32(/*REG_DITHER*/0x302060, 0);
    GDTR.wr32(/*REG_CSPREAD */0x302068, 0);

   GDTR.wr32(0x300000, 0x020000);
   GDTR.wr32(0x300004, 0x260007);
   GDTR.wr32(0x300008, 0x000000);
   
   GDTR.wr32(0x302054, 0x02);   
   
   GDTR.wr16(0x302098, 0xffff);
   GDTR.wr16(0x30209C, 0xffff);
   
   GDTR.wr32(/*REG_PCLK*/0x302070, 2);
   
 
   GDTR.wr32(0x300000, 0x020000);

   GDTR.wr32(0x300004, 0x260007);

   GDTR.wr32(0x300008, 0x000000);


Thank you in advance for your help  :)
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Re: Migrate from ft811 to bt815
« Reply #5 on: September 03, 2019, 10:53:50 AM »

Hello Florian,

It is recommended that you implement the following start up sequence (including the checks for REG_ID and REG_CPURESET):
Code: [Select]
    MCU_PDlow();                                                                // PD low to reset device                                                               
    MCU_Delay_20ms();
    MCU_PDhigh();                                                               // PD high again
    MCU_Delay_20ms();

    // ---------------------- Optional clock configuration ---------------------   

    // Un-comment this line if using external crystal. Leave commented if using internal oscillator.
    // Note that most FTDI/BRT modules based on FT800/FT801 use an external crystal
    // EVE_CmdWrite(0x44, 0x00);           // 0x44 = HostCMD_CLKEXT

    // You can also send the host command to set the PLL here if you want to change it from the default
    // of 48MHz (FT80x) or 60MHz (FT81x)
    // The command would be called here before the Active command wakes up the device   
   
    // ---------- Wake FT8xx and delay to allow device to start-up -------------   
   
    EVE_CmdWrite(FT81x_ACTIVE, 0x00);                                           // Sends 00 00 00 to wake FT8xx
    MCU_Delay_500ms();                                                          // 500ms delay (EVE requires at least 300ms here))
   
    // --------------- Check that FT8xx ready and SPI comms OK -----------------
   
    while (EVE_MemRead8(REG_ID) != 0x7C)                                        // Read REG_ID register (0x302000) until reads 0x7C
    {
    }
     
    while (EVE_MemRead8(REG_CPURESET) != 0x00)                                  // Ensure CPUreset register reads 0 and so FT8xx is ready   
    {
    }

Can you also try using a slower SPI rate until you have set the display settings, I would suggest 11Mhz, after which you can up the SPI rate again. Finally please ensure the settings you are using are correct for your given display.

Best Regards,
BRT Community
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FlorianG

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Re: Migrate from ft811 to bt815
« Reply #6 on: September 04, 2019, 12:02:06 AM »

thank you for your reply,

I add:

 MCU_PDlow();                                                                // PD low to reset device                                                               
    MCU_Delay_20ms();
    MCU_PDhigh();                                                               // PD high again
    MCU_Delay_20ms();

And without:
GDTR.hostcmd(0x44);
GDTR.hostcmd(0x61);
GDTR.hostcmd(0x62);

I also lower the speed of the SPI to 11Mhz.

The REG_ID is the value 0x7c and 0x00 for the REG_CPURESET
The result on the screen is the same.
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Re: Migrate from ft811 to bt815
« Reply #7 on: September 04, 2019, 11:05:13 AM »

Hello,

If REG_ID is reading 0x7c and REG_CPURESET is reading 0x00 the IC is initialized correctly.
 
Again I would double check the settings for your screen are correct.
I would also not attempt to write a Display List until after you have set REG_PCLK.

I suspect the issue is with the writing of the Display List, can you get SPI capture of the transactions from your MCU to EVE?

Best Regards,
BRT Community
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FlorianG

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Re: Migrate from ft811 to bt815
« Reply #8 on: September 04, 2019, 02:45:04 PM »

Hi,

I can not capture what I send to the bt816 but in return all that I send to it is in what I sent you.

PS. NOT if I do not send "REG_PCLK" the screen becomes more and more white
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Re: Migrate from ft811 to bt815
« Reply #9 on: September 04, 2019, 03:43:12 PM »

Hello,

We find in cases where the screen exhibits the behaviour you are seeing that there is a disparity between what you think you have sent EVE over SPI and what you have actually sent from your MCU to the EVE IC.

To debug this properly you will need to find a way to capture the SPI transactions, MOSI/MISO/CS/SCLK are all pertinent.

Best Regards,
BRT Community
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