HI,
I'm using LMP91000 to convert current sensing from NO2 sensor -Spec sensor.
For configuration, I used Webench tool. I2C is stablished and measuring ADC value approximately is correct. The configuration is as follow>
void lmp91000_CO_cfg(void)
{
uint8_t result;
nrf_gpio_pin_clear(LMP91000_MENB_PIN);
nrf_delay_ms(1);
do
{
result = lmp91000_get_status();
} while (result != 1);
lmp91000_clear_lock();
//nrf_delay_ms(1);
Twiface_writeReg(This, LMP91000_TIACN_REG, LMP91000_TIA_GAIN_350KOHM | LMP91000_TIA_RLOAD_10);
//nrf_delay_ms(1);
Twiface_writeReg(This, LMP91000_REFCN_REG, LMP91000_REF_SOURCE_EXTERNAL | LMP91000_INT_ZERO_20 | LMP91000_BIAS_POSITIVE | LMP91000_BIAS_0);
//nrf_delay_ms(1);
Twiface_writeReg(This, LMP91000_MODECN_REG, LMP91000_SHORTING_FET_DISABLED | LMP91000_OP_MODE_3_LEAD_CELL);
lmp91000_set_lock();
nrf_delay_ms(1);
nrf_gpio_pin_set(LMP91000_MENB_PIN);
}
bool lmp91000_init(void)
{
nrf_delay_ms(100);
nrf_gpio_cfg_input(LMP91000_VOUT_PIN, NRF_GPIO_PIN_NOPULL);
nrf_gpio_cfg_output(LMP91000_MENB_PIN);
Twiface_initDevice(
This, LMP91000_NAME, LMP91000_TWIUNIT, LMP91000_TWIFREQ,
LMP91000_DEVADDR, LMP91000_SDA, LMP91000_SCL);
return true;
}
# the problem is when I exposed the sensor to gas there is not change in ADC output that I monitor on LCD.
I have done the same and it works for CO gas sensor from the same family.
Even I tried external resistor and filter design but it does not work.
please, any assistance is appreciated.
Regards,
Mostafa
