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What's the default state of LIS3DSH interrupt pins, and can they be configured as high-impedance?

Gianluca Nitti


as the title says I'm interested in understanding more about how the INT1/INT2 pins of the LIS3DSH MEMS accelerometer work. Are they push-pull or open-drain? If it's not the default, is it possible to configure the sensor to not drive them (i.e. high impedance state)?

I'm reading in Table 61 of the datasheet that by default the INT2_EN and INT1_EN bits of CTRL_REG3 are set to 0, thus the INT1 and INT2 signals are "disabled". Does "disabled" mean the signal is not driven, and thus it can be driven externally without damage, or that it's tied low/high internally?

For context, I'm asking because I'm interested in bit-banging a 16-bit bidirectional parallel bus from a STM32F4DISCOVERY board, and according to Table 7 in the manual it looks like PORT E would be ideal for this purpose as almost all of the 16 pins are free I/O; 3 of them however are tied to the motion sensor's INT1,INT2 and CS_I2C/SPI pins respectively. Thus I'd like to know if I can safely drive the entire PORT E from the MCU if I don't need the motion sensor.

I found application note AN3308 for a similar sensor, the LIS3DH, which clearly says in Table 1 that the INT pins are by default push-pull forced to GND (thus if I understand correctly with this sensor it wouldn't be possible to do what I described above?) but I can't find whether the situation is the same with the LIS3DSH which is on my discovery board.

Gianluca Nitti

Up. Can anyone clarify what - for example -  "INT2 signal disabled" means in Table 61 of LIS3DSH's datasheet? Is the pin in high impedance mode or is it pulled low/high?