nrf9160 gpio low is not voltage 0, help

[fatalfeel]

const struct device* gpio_dev = device_get_binding("GPIO_0");
err = gpio_config(gpio_dev,
tx_pin,
NRF_GPIO_PIN_S0S1);

for(i=0 ;; i++)
{
printk("nrf_gpio_pin_write");

if( i%2 == 0 )
nrf_gpio_pin_write(tx_pin, 0);
else
nrf_gpio_pin_write(tx_pin, 1);

k_usleep(100000);
}

the low voltage is 1.2v

/// nRF9160_PS_v2.0.pdf p. 101

nrfjprog -f NRF91 --memrd 0x50842504 --w 16 --n 64
0x50842504: 0002 1400 0002 1400 0002 1400 0043 D400 |............C...|
0x50842514: 8002 1400 8002 1400 8002 1400 0000 0000 |................|
0x50842524: 0000 0000 0000 0000 0000 0000 0000 0000 |................|
0x50842534: 0000 0000 0000 0000 0000 0000 0000 0000 |................|

///

how to change to 0v

[fatalfeel]

/////////////I got answer

static void Test_GPIOTE()
{
int i;
int err;

nrfx_gpiote_in_config_t in_config =
{
.sense = NRF_GPIOTE_POLARITY_LOTOHI,
.pull = NRF_GPIO_PIN_PULLUP,
.is_watcher = false,
.hi_accuracy = true,
.skip_gpio_setup = false
};

IRQ_DIRECT_CONNECT(GPIOTE0_IRQn, 0, nrfx_gpiote_irq_handler, 0);
irq_enable(GPIOTE0_IRQn);

err = nrfx_gpiote_init(0);
if (err != NRFX_SUCCESS)
{
printf("nrfx_gpiote_init error: %08x", err);
return;
}

err = nrfx_gpiote_in_init(rx_pin, &in_config, rx_event_handler);
if (err != NRFX_SUCCESS)
{
printf("nrfx_gpiote_in_init error: %08x", err);
return;
}

nrfx_gpiote_in_event_enable(rx_pin, true);

////////////////////////////////can not before nrfx_gpiote_init and nrfx_gpiote_out_init(tx_pin, &out_config); ////////////////////////////////
////////////////beause nrfx_gpiote_init call -> nrf_gpio_cfg_output of ~/ncs/modules/hal/nordic/nrfx/hal/nrf_gpio.h
//add this
nrf_gpio_cfg(tx_pin,
NRF_GPIO_PIN_DIR_OUTPUT,
NRF_GPIO_PIN_INPUT_DISCONNECT,
NRF_GPIO_PIN_NOPULL,
NRF_GPIO_PIN_H0H1,       //use this, low will be 0.4v
NRF_GPIO_PIN_NOSENSE);

///////////////////////////////////////////////////

for(i=0 ;; i++)
{
printk("nrf_gpio_pin_write");

if( i%2 == 0 )
nrf_gpio_pin_write(tx_pin, 0);
else
nrf_gpio_pin_write(tx_pin, 1);

k_usleep(10000);
}
}

//////////////////////////////////////////////////////////////////////////////another problm
now high is 1.8v and low is 0.45v

Could set low to 0.0v

Can software to do this?

or need hardware to solve?

[Kenneth]

It sounds to me that there is some circuitry on the pin that is trying to pull the pin high. By using high drive mode you are able to pull the pin lower, but you should look into what may be pulling that pin high externally.

Kenneth

[fatalfeel]

now high is 1.8v and low is 0.45v

Could set low to 0.0v

Can software to do this?

or need hardware to solve?

[Kenneth]

fatalfeel said:

Can software to do this?

 No. It must be some external hardware.

[fatalfeel]

thanks a lot man~~~~