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Author Topic: BT815 - Wake-Up via interrupt  (Read 6259 times)

Jonathan

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BT815 - Wake-Up via interrupt
« on: April 10, 2022, 07:43:47 PM »

Hello,

I have a question about the possibilities of the interrupt pin. I want that any touch event triggers the interrupt. Especially when the display is in power-down state. From the docs I get, that in power-down state my wanted behaviour should be default. But nothing happens, I get no interrupts at all. Where do I have to set up the interrupt in the eve3-code? (I am using Rudolphs library)
Also I test the ISR from my MCU with a random button as interrupt source and this part works just fine. When I power up the display and do the init process I also get 2 interrupts, why? I can not find the source for them...

Best,
Jonathan
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Re: BT815 - Wake-Up via interrupt
« Reply #1 on: April 15, 2022, 01:25:53 PM »

Hi Jonathan,

The INT pin should follow the state of the interrupt from the capacitive touch panel when the BT81x is in sleep mode. If you scope the INT output from EVE and put EVE into the sleep mode, you should see low pulses each time you touch the screen.

In active mode, you can check the REG_INT_FLAGS to see which source caused the interrupt. Note that reading it will clear the flags and so when you see INT low the first read will give the flags.

The Interrupt operates similarly to most MCUs whereby you have the global INT bit (REG_INT_EN) to enable interrupts and then you have mask bits to determine which sources will generate an interrupt (REG_INT_MASK). Once the INT pin is asserted, your MCU should read REG_INT_FLAGS to see which source caused it. We have a table of interrupt sources in the BT815/6 datasheet in the Interrupts Section which you can use to see which bits correspond to which source

Some interrupts will occur periodically in normal operation (such as swap) whereas others will only be activated by a user action (such as TAG when the user touches the screen and the tag changes). However, you can set the mask bits such that only the sources you require will generate an interrupt. You may use the TAG or TOUCH interrupt for the application you mentioned where the interrupt occurs on a user touch.

Best Regards, BRT Community



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Jonathan

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Re: BT815 - Wake-Up via interrupt
« Reply #2 on: January 12, 2024, 04:24:03 PM »

Hi,

Do I understand the datasheet of the BT815 correctly: When the bt815 has only power, but is never activated (PD_N is never pulled HIGH), then the INT_N pin follows the interrupt of the capacitive screen?
Or do I have to set BT815 to active state, do some settings and when I go back to powerdown state, then I get this behaviour?

The datasheet says in 4.8.8.:
Quote
For capacitive touch, the INT_N pin will follow CTP_INT_N pin when the BT815 is in STANDBY, SLEEP or
POWERDOWN state.

EDIT:
I got it running and it is just like the docs says.
In case you work with a esp32 -> Keep in mind that you need to configure the RTC-pin for the wakeup from deep-sleep right before the deep-sleep command.
« Last Edit: January 15, 2024, 09:47:15 AM by Jonathan »
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Re: BT815 - Wake-Up via interrupt
« Reply #3 on: January 18, 2024, 03:29:18 PM »

Hi Jonathan,
Glad you got it working and thanks for the tip on ESP32,
Best Regards, BRT Community
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