mirror of https://github.com/kidoman/embd
105 lines
1.9 KiB
Go
105 lines
1.9 KiB
Go
// Package mcp4725 allows interfacing with the MCP4725 DAC.
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package mcp4725
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import (
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"log"
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"sync"
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"github.com/kidoman/embd"
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)
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const (
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dacReg = 0x40
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programReg = 0x60
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powerDown = 0x46
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genReset = 0x06
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powerUp = 0x09
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)
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// MCP4725 represents a MCP4725 DAC.
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type MCP4725 struct {
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// Bus to communicate over.
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Bus embd.I2CBus
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// Addr of the sensor.
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Addr byte
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initialized bool
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mu sync.RWMutex
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// Debug turns on additional debug output.
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Debug bool
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}
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// New creates a new MCP4725 sensor.
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func New(bus embd.I2CBus, addr byte) *MCP4725 {
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return &MCP4725{
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Bus: bus,
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Addr: addr,
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}
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}
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func (d *MCP4725) setup() (err 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
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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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if d.Debug {
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log.Print("mcp4725: general call reset")
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}
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if err = d.Bus.WriteByteToReg(d.Addr, 0x00, powerUp); err != nil {
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return
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}
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if err = d.Bus.WriteByteToReg(d.Addr, 0x00, genReset); err != nil {
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return
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}
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d.initialized = true
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return
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}
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func (d *MCP4725) setVoltage(voltage int, reg byte) (err error) {
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if err = d.setup(); err != nil {
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return
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}
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if voltage > 4095 {
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voltage = 4095
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}
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if voltage < 0 {
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voltage = 0
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}
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if d.Debug {
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log.Printf("mcp4725: setting voltage to %04d", voltage)
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}
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if err = d.Bus.WriteWordToReg(d.Addr, reg, uint16(voltage<<4)); err != nil {
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return
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}
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return
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}
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// SetVoltage sets the output voltage.
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func (d *MCP4725) SetVoltage(voltage int) (err error) {
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return d.setVoltage(voltage, dacReg)
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}
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// SetPersistedVoltage sets the voltage and programs the EEPROM so
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// that the voltage is restored on reboot.
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func (d *MCP4725) SetPersistedVoltage(voltage int) (err error) {
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return d.setVoltage(voltage, programReg)
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}
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// Close puts the DAC into power down mode.
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func (d *MCP4725) Close() (err error) {
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if d.Debug {
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log.Print("mcp4725: powering down")
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}
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if err = d.Bus.WriteWordToReg(d.Addr, powerDown, 0); err != nil {
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return
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}
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return
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}
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