HTS221 support

[deadprogram]

We need support for the HTS221 capacitive digital sensor for relative humidity and temperature.

It is one of the sensors onboard the Arduino Nano 33 BLE Sense.

[deadprogram]

See https://content.arduino.cc/assets/Nano_BLE_Sense_HTS221.pdf

[sago35]

The following may be helpful.

https://github.com/arduino-libraries/Arduino_HTS221

[alankrantas]

Tried to look into it. I tried to raise a response with the "who am I" register but... the code would simply hang on any I2C operations.

func main() {

	const HTS221_ADDRESS = 0x5F
	const HTS221_WHO_AM_I_REG = 0x0F

	i2c := machine.I2C1
	i2c.Configure(machine.I2CConfig{
		SCL:       machine.P0_15,  // SCL1
		SDA:       machine.P0_14,  // SDA1
	})

	data := []byte{0}
	err := i2c.ReadRegister(HTS221_ADDRESS, HTS221_WHO_AM_I_REG, data)
	println(data[0], err)

}

schematics

If I set to other pins or set nothing I would get an "I2C bus error". I couldn't get "who am I" response from LSM9DS1 either (also stuck). I can ping all onboard devices with the Arduino I2C scanner script.

Is there any way to check if the SCL1/SDA1 pins are working properly in TinyGo?

[sago35]

@alankrantas
I tried it with feather-nrf52840-sense, which has the same nRF52840 microcontroller.
It did not work when the I2C initialization part was set to I2C1.

Try changing it to I2C0 and see if it works.
If it does, there may be some changes needed in machine_nrf.go.

Either of the following will work

	// It works (I2C0)
	machine.I2C0.Configure(machine.I2CConfig{
		Frequency: machine.TWI_FREQ_400KHZ,
		SDA:       machine.P0_14,
		SCL:       machine.P0_15,
	})

	// It works (I2C1)
	machine.I2C1.Configure(machine.I2CConfig{
		Frequency: machine.TWI_FREQ_400KHZ,
		SDA:       machine.P0_14,
		SCL:       machine.P0_15,
	})

[sago35]

NewI2C(). I forgot to change the part that passes to ssd1306.
I2C0 and machine.I2C1 both worked.
The above comment has been corrected.

[sago35]

@alankrantas
You probably need to set VDD_ENV (P0_22).
This is an output pin and probably needs to be set high to turn on the HTS221 power supply.

[alankrantas]

@sago35 Thanks! I got responses from both HTS221 and LSM9DS1.

It turns out I have to set both VCC_ENV (P0_22) (device power) and R_PULLUP (P1_00) (pull up the I2C1 bus) to high and wait a bit, like 5 ms at least, before any I2C operation.