Can someone to explain me this behaviour?

[dotatbg]

The code

Code: [Select all] [Expand/Collapse]

1. gpio_config_t io_conf = {};
2.     gpio_num_t gpio_test_pin =  GPIO_NUM_5;
3.     io_conf.intr_type = GPIO_INTR_DISABLE;
4.     io_conf.mode = GPIO_MODE_INPUT_OUTPUT_OD;
5.     io_conf.pin_bit_mask = BIT64(gpio_test_pin);
6.     io_conf.pull_down_en = 1;
7.     io_conf.pull_up_en = 1;
8.     gpio_config(&io_conf);
9.     gpio_dump_io_configuration(stdout, BIT64(gpio_test_pin));
10.     ESP_LOGW("MUXREG", "%lX = %lx", GPIO_PIN_MUX_REG[gpio_test_pin], READ_PERI_REG(GPIO_PIN_MUX_REG[gpio_test_pin]));
11.     gpio_pullup_en(gpio_test_pin);
12.     gpio_pulldown_en(gpio_test_pin);
13.     ESP_LOGW("MUXREG", "%lX = %lx", GPIO_PIN_MUX_REG[gpio_test_pin], READ_PERI_REG(GPIO_PIN_MUX_REG[gpio_test_pin]));
14.     gpio_dump_io_configuration(stdout, BIT64(gpio_test_pin));
15.     REG_SET_BIT(GPIO_PIN_MUX_REG[gpio_test_pin], FUN_PU);
16.     gpio_dump_io_configuration(stdout, BIT64(gpio_test_pin));

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Result GPIO_NUM_5

Code: [Select all] [Expand/Collapse]

1. I (400) gpio: GPIO[5]| InputEn: 1| OutputEn: 1| OpenDrain: 1| Pullup: 1| Pulldown: 1| Intr:0
2. ================IO DUMP Start================
3. IO[5] -
4.   Pullup: 1, Pulldown: 1, DriveCap: 2
5.   InputEn: 1, OutputEn: 1, OpenDrain: 1
6.   FuncSel: 2 (GPIO)
7.   GPIO Matrix SigOut ID: 256 (simple GPIO output)
8.   GPIO Matrix SigIn ID: (simple GPIO input)
9.   SleepSelEn: 0
10.  
11. =================IO DUMP End==================
12. W (430) MUXREG: 3FF4906C = 2b80
13. W (440) MUXREG: 3FF4906C = 2b80
14. ================IO DUMP Start================
15. IO[5] -
16.   Pullup: 1, Pulldown: 1, DriveCap: 2
17.   InputEn: 1, OutputEn: 1, OpenDrain: 1
18.   FuncSel: 2 (GPIO)
19.   GPIO Matrix SigOut ID: 256 (simple GPIO output)
20.   GPIO Matrix SigIn ID: (simple GPIO input)
21.   SleepSelEn: 0
22.  
23. =================IO DUMP End==================
24. ================IO DUMP Start================
25. IO[5] -
26.   Pullup: 1, Pulldown: 1, DriveCap: 2
27.   InputEn: 1, OutputEn: 1, OpenDrain: 1
28.   FuncSel: 2 (GPIO)
29.   GPIO Matrix SigOut ID: 256 (simple GPIO output)
30.   GPIO Matrix SigIn ID: (simple GPIO input)
31.   SleepSelEn: 0
32.  
33. =================IO DUMP End==================

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Result GPIO_NUM_2

Code: [Select all] [Expand/Collapse]

1. I (400) gpio: GPIO[2]| InputEn: 1| OutputEn: 1| OpenDrain: 1| Pullup: 1| Pulldown: 1| Intr:0
2. ================IO DUMP Start================
3. IO[2] -
4.   Pullup: 0, Pulldown: 1, DriveCap: 2
5.   InputEn: 1, OutputEn: 1, OpenDrain: 1
6.   FuncSel: 2 (GPIO)
7.   GPIO Matrix SigOut ID: 256 (simple GPIO output)
8.   GPIO Matrix SigIn ID: (simple GPIO input)
9.   SleepSelEn: 0
10.  
11. =================IO DUMP End==================
12. W (430) MUXREG: 3FF49040 = 2a80
13. W (440) MUXREG: 3FF49040 = 2a80
14. ================IO DUMP Start================
15. IO[2] -
16.   Pullup: 0, Pulldown: 1, DriveCap: 2
17.   InputEn: 1, OutputEn: 1, OpenDrain: 1
18.   FuncSel: 2 (GPIO)
19.   GPIO Matrix SigOut ID: 256 (simple GPIO output)
20.   GPIO Matrix SigIn ID: (simple GPIO input)
21.   SleepSelEn: 0
22.  
23. =================IO DUMP End==================
24. ================IO DUMP Start================
25. IO[2] -
26.   Pullup: 1, Pulldown: 1, DriveCap: 2
27.   InputEn: 1, OutputEn: 1, OpenDrain: 1
28.   FuncSel: 2 (GPIO)
29.   GPIO Matrix SigOut ID: 256 (simple GPIO output)
30.   GPIO Matrix SigIn ID: (simple GPIO input)
31.   SleepSelEn: 0
32.  
33. =================IO DUMP End==================

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Chip is ESP32-WROVER-B

[MicroController]

Can you explain why you'd want to have both pull-up and pull-down enabled at the same time?

[dotatbg]

For no reason... DC Bias for example. But you answer is not an explanation

[MicroController]

I guess it's not. And stating that it's not a good idea to pull digital inputs to a voltage right between high and low is not an explanation either