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soypat
76 lines
2.2 KiB
Go
76 lines
2.2 KiB
Go
// Package lps22hb implements a driver for LPS22HB, a MEMS nano pressure sensor.
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//
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// Datasheet: https://www.st.com/resource/en/datasheet/dm00140895.pdf
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package lps22hb
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import (
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"tinygo.org/x/drivers"
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"tinygo.org/x/drivers/internal/legacy"
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)
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// Device wraps an I2C connection to a HTS221 device.
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type Device struct {
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bus drivers.I2C
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Address uint8
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}
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// New creates a new LPS22HB connection. The I2C bus must already be
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// configured.
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//
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// This function only creates the Device object, it does not touch the device.
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func New(bus drivers.I2C) Device {
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return Device{bus: bus, Address: LPS22HB_ADDRESS}
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}
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// ReadPressure returns the pressure in milli pascals (mPa).
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func (d *Device) ReadPressure() (pressure int32, err error) {
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d.waitForOneShot()
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// read data
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data := []byte{0, 0, 0}
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_PRESS_OUT_REG, data[:1])
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_PRESS_OUT_REG+1, data[1:2])
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_PRESS_OUT_REG+2, data[2:])
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pValue := float32(uint32(data[2])<<16|uint32(data[1])<<8|uint32(data[0])) / 4096.0
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return int32(pValue * 1000), nil
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}
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// Connected returns whether LPS22HB has been found.
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// It does a "who am I" request and checks the response.
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func (d *Device) Connected() bool {
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data := []byte{0}
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_WHO_AM_I_REG, data)
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return data[0] == 0xB1
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}
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// ReadTemperature returns the temperature in celsius milli degrees (°C/1000).
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func (d *Device) ReadTemperature() (temperature int32, err error) {
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d.waitForOneShot()
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// read data
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data := []byte{0, 0}
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_TEMP_OUT_REG, data[:1])
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_TEMP_OUT_REG+1, data[1:])
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tValue := float32(int16(uint16(data[1])<<8|uint16(data[0]))) / 100.0
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return int32(tValue * 1000), nil
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}
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// private functions
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// wait and trigger one shot in block update
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func (d *Device) waitForOneShot() {
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// trigger one shot
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legacy.WriteRegister(d.bus, d.Address, LPS22HB_CTRL2_REG, []byte{0x01})
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// wait until one shot is cleared
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data := []byte{1}
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for {
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legacy.ReadRegister(d.bus, d.Address, LPS22HB_CTRL2_REG, data)
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if data[0]&0x01 == 0 {
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break
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}
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}
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}
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