mirror of https://github.com/kidoman/embd
120 lines
3.0 KiB
Go
120 lines
3.0 KiB
Go
/*
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* Copyright (c) Karan Misra 2014
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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* associated documentation files (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge, publish, distribute,
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* sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all copies or
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* substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
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* NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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// Package mcp4725 allows interfacing with the MCP4725 DAC.
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package mcp4725
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import (
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"sync"
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"github.com/cfreeman/embd"
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"github.com/golang/glog"
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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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}
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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() 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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glog.V(1).Infof("mcp4725: general call reset")
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if err := d.Bus.WriteByteToReg(d.Addr, 0x00, powerUp); err != nil {
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return err
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}
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if err := d.Bus.WriteByteToReg(d.Addr, 0x00, genReset); err != nil {
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return err
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}
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d.initialized = true
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return nil
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}
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func (d *MCP4725) setVoltage(voltage int, reg byte) error {
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if err := d.setup(); err != nil {
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return err
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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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glog.V(2).Infof("mcp4725: setting voltage to %04d", voltage)
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if err := d.Bus.WriteWordToReg(d.Addr, reg, uint16(voltage<<4)); 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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// SetVoltage sets the output voltage.
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func (d *MCP4725) SetVoltage(voltage int) 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) 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() error {
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glog.V(1).Infof("mcp4725: powering down")
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if err := d.Bus.WriteWordToReg(d.Addr, powerDown, 0); 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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