mirror of
https://github.com/kidoman/embd
synced 2024-06-01 08:38:05 +02:00
132 lines
2.3 KiB
Go
132 lines
2.3 KiB
Go
// Package ina219 allows interfacing with Texas Instruments INA219 current
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// monitor. This is a high side current and voltage monitor with and I2C
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// interfcace.
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// TODO - add options to config voltage range, sensitivity and averaging
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package ina219
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import (
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"math"
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"sync"
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"github.com/golang/glog"
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"github.com/kidoman/embd"
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)
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const (
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configReg = 0x00
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shuntVReg = 0x01
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busVReg = 0x02
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powerReg = 0x03
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currentReg = 0x04
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calibReg = 0x05
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)
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// INA219 represents a Bosch INA219 current sensor.
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type INA219 struct {
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Bus embd.I2CBus
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address byte
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shuntResitance float64
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initialized bool
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mu sync.RWMutex
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}
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func New(bus embd.I2CBus, addr byte, shunt float64) *INA219 {
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ina := INA219{
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Bus: bus,
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address: addr,
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shuntResitance: shunt,
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}
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return &ina
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}
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func (d *INA219) setup() error {
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d.mu.RLock()
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if d.initialized {
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d.mu.RUnlock()
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return nil
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}
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d.mu.RUnlock()
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d.mu.Lock()
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defer d.mu.Unlock()
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config := uint16(0x219F) // 12, bit no integration, 32v bus range , 40mV shunt range
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err := d.Bus.WriteWordToReg(d.address, configReg, config)
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if err != nil {
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return err
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}
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calib := uint16(0.5 + 40.96/d.shuntResitance)
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err = d.Bus.WriteWordToReg(d.address, calibReg, calib) // .1 ohm sense resitor
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if err != nil {
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return err
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}
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glog.V(1).Infof("ina219: initaliized")
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d.initialized = true
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return nil
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}
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func (d *INA219) ShuntVoltage() (float64, error) {
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if err := d.setup(); err != nil {
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return math.NaN(), err
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}
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v, err := d.Bus.ReadWordFromReg(d.address, shuntVReg)
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if err != nil {
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return math.NaN(), err
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}
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voltage := float64(v) / 100000.0
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return voltage, nil
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}
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func (d *INA219) Voltage() (float64, error) {
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if err := d.setup(); err != nil {
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return math.NaN(), err
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}
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v, err := d.Bus.ReadWordFromReg(d.address, busVReg)
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if err != nil {
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return math.NaN(), err
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}
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voltage := float64(v>>3) / 250.0
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return voltage, nil
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}
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func (d *INA219) Current() (float64, error) {
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if err := d.setup(); err != nil {
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return math.NaN(), err
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}
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v, err := d.Bus.ReadWordFromReg(d.address, currentReg)
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if err != nil {
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return math.NaN(), err
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}
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current := float64(v) / 1000.0
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return current, nil
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}
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// Close
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func (d *INA219) Close() error {
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// put in power down mode
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config := uint16(0x0000)
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err := d.Bus.WriteWordToReg(d.address, configReg, config)
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if err != nil {
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return err
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}
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return nil
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}
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