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Author Topic: Standby mode  (Read 647 times)

raydem

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Standby mode
« on: December 18, 2021, 02:38:37 AM »

Hello,
Question.... When send the command Standby (0x41) the display should turns off?
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Re: Standby mode
« Reply #1 on: December 20, 2021, 11:55:46 AM »

Hello,

Thank you for your question, when the device is placed into standby mode the system clock applied to the graphics core is disabled, however the previous screen may persist on the LCD panel. As such we would recommend issuing a blank screen to EVE before issuing any power state host commands to the IC.

Code: [Select]
    ramDisplayList = RAM_DL;                                                    // start of Display List
    EVE_MemWrite32(ramDisplayList, 0x02000000);                                 // Clear Color RGB sets the colour to clear screen to

    ramDisplayList += 4;                                                        // point to next location
    EVE_MemWrite32(ramDisplayList, (0x26000000 | 0x00000007));                  // Clear 00100110 -------- -------- -----CST  (C/S/T define which parameters to clear)

    ramDisplayList += 4;                                                        // point to next location
    EVE_MemWrite32(ramDisplayList, 0x00000000);                                 // DISPLAY command 00000000 00000000 00000000 00000000 (end of display list)

    EVE_MemWrite32(REG_DLSWAP, DLSWAP_FRAME);                                   // Swap display list to make the edited one active


Best Regards,
BRT Community
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raydem

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Re: Standby mode
« Reply #2 on: December 20, 2021, 12:53:55 PM »

Thank you for the answer.

When send the command 0x41 (Standbye mode) the LCD panel turns off.  It is able to back to active only with the command 0x00 (Active), and the LCD panel turns on. Any idea why the display turns off? I need to show the last screen in the LCD panel.
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Re: Standby mode
« Reply #3 on: December 20, 2021, 01:41:28 PM »

Hello,

Yes when the graphics core is placed into STANDBY it will not be driving the display pins on the IC, thus it appears as if the display has turned off. Unfortunately if your require the last screen to be persistent on the LCD panel the only way to guarantee this is by keeping EVE in the ACTIVE state.

Best Regards,
BRT Community
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raydem

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Re: Standby mode
« Reply #4 on: December 22, 2021, 05:24:55 PM »

Thank you, It will be possible to do anything externally with the pinouts to be persistent on the LCD panel? Maybe some pinouts with pull up or something?
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Re: Standby mode
« Reply #5 on: December 23, 2021, 10:06:08 AM »

Hello,

This will depend on the LCD itself and whether it can keep the last image when receiving no new data. The behavior seen may vary between different types/makes of LCD panel.

One consideration in any case would be whether the standby mode is necessary? The power used by EVE would probably be a lot less than the power taken by the LCD and backlight and so reducing the EVE consumption may not be a big overall saving if you will be keeping these on. Putting EVE to a low power state and the LCD/backlight would offer a bigger saving.

If you keep EVE and the LCD in active state, EVE will hold the last display list and so if your main aim is to hold the image without needing to communicate with the display part of the system then keeping EVE and the LCD active would achieve this.

Best Regards, BRT Community

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