RE: TWI scan no device found

pouyae — Thu, 25 Feb 2021 22:38:44 GMT

Found the issue. One of the sensors was mounted upside down on the PCB. Sorry for taking your time!

RE: TWI scan no device found

pouyae — Thu, 25 Feb 2021 21:22:56 GMT

[quote userid="18935" url="~/f/nordic-q-a/72074/twi-scan-no-device-found/296391#296391"]

Bad sign. On an idle I²C bus, both lines need to be high, or rather pulled up by the pullup resistor.

[/quote]

I have pull up resistors on both SCL and SDA. Do I need to disable internal pull ups for this to function correctly? I've tried

nrf_gpio_cfg_input(SDA_PIN, NRF_GPIO_PIN_NOPULL);
NRF_GPIO->PIN_CNF[SDA_PIN] |= (GPIO_PIN_CNF_DRIVE_H0H1 << GPIO_PIN_CNF_DRIVE_Pos);
NRF_GPIO->PIN_CNF[SDA_PIN] |= ((GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos));

nrf_gpio_cfg_input(SCL_PIN, NRF_GPIO_PIN_NOPULL);
NRF_GPIO->PIN_CNF[SCL_PIN] |= (GPIO_PIN_CNF_DRIVE_H0H1 << GPIO_PIN_CNF_DRIVE_Pos);
NRF_GPIO->PIN_CNF[SCL_PIN] |= ((GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos));

And also

#define TWI_PIN_INIT(_pin) nrf_gpio_cfg((_pin),                     \
                                        NRF_GPIO_PIN_DIR_INPUT,     \
                                        NRF_GPIO_PIN_INPUT_CONNECT, \
                                        NRF_GPIO_PIN_NOPULL,        \
                                        NRF_GPIO_PIN_S0D1,          \
                                        NRF_GPIO_PIN_NOSENSE)

And also

#define SCL_PIN_INIT_CONF     ( (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos) \
                              | (GPIO_PIN_CNF_DRIVE_S0D1     << GPIO_PIN_CNF_DRIVE_Pos) \
                              | (GPIO_PIN_CNF_PULL_Pullup    << GPIO_PIN_CNF_PULL_Pos)  \
                              | (GPIO_PIN_CNF_INPUT_Connect  << GPIO_PIN_CNF_INPUT_Pos) \
                              | (GPIO_PIN_CNF_DIR_Input      << GPIO_PIN_CNF_DIR_Pos))

but they didn't make any difference.

[quote userid="18935" url="~/f/nordic-q-a/72074/twi-scan-no-device-found/296391#296391"]Those GPIO pins are current limited - do you reach the voltage for correct sensor operation?[/quote]

The sensors I'm using require microamps to function, and I've set GPIO_PIN_CNF_DRIVE_H0H1 on P0.08. The output voltage is 2.98 which is in range for the sensors.

RE: TWI scan no device found

Turbo J — Thu, 25 Feb 2021 21:14:11 GMT

[quote userid="101922" url="~/f/nordic-q-a/72074/twi-scan-no-device-found"]Checking SCL and SDA after TWI init, SCL is high, and SDA is low.[/quote]

Bad sign. On an idle I²C bus, both lines need to be high, or rather pulled up by the pullup resistor.

[quote userid="101922" url="~/f/nordic-q-a/72074/twi-scan-no-device-found"]Sensors are powered up using P0.08[/quote]

Those GPIO pins are current limited - do you reach the voltage for correct sensor operation?