mirror of https://github.com/kidoman/embd
383 lines
14 KiB
Go
383 lines
14 KiB
Go
// Package mcp9808 is a driver for the MCP9808 temperature sensor
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// and all code is based off of the documentation found here:
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// http://ww1.microchip.com/downloads/en/DeviceDoc/25095A.pdf
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package mcp9808
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import "github.com/kidoman/embd"
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const (
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// default I2C address for device
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address = 0x18
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// Register addresses.
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regConfig = iota // starts at 1, this is what we want
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regUpperTemp
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regLowerTemp
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regCriticalTemp
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regAmbientTemp
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regManufID
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regDeviceID
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regResolution
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)
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const (
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configAlertMode uint16 = 1 << iota
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configAlertPolarity
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configAlertSelect
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configAlertControl
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configAlertStatus
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configInterruptClear
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configWindowTempLock
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configCriticalTempLock
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configShutDown
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)
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// MCP9808 represents a MCP9808 temperature sensor.
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type MCP9808 struct {
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Bus embd.I2CBus
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config uint16
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}
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// New returns a handle to a MCP9808 sensor.
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func New(bus embd.I2CBus) (*MCP9808, error) {
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d := &MCP9808{Bus: bus}
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// initialize the configuration
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_, err := d.Config()
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return d, err
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}
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// ManufacturerID reads the device manufacturer ID
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func (d *MCP9808) ManufacturerID() (uint16, error) {
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return d.Bus.ReadWordFromReg(address, regManufID)
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}
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// DeviceID reads the device ID and revision
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func (d *MCP9808) DeviceID() (uint8, uint8, error) {
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devIDRev, err := d.Bus.ReadWordFromReg(address, regDeviceID)
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if err != nil {
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return 0, 0, err
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}
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return uint8(devIDRev >> 8), uint8(devIDRev & 0xFF), nil
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}
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// Config gets the config word from the device.
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func (d *MCP9808) Config() (uint16, error) {
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config, err := d.Bus.ReadWordFromReg(address, regConfig)
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if err != nil {
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return 0, err
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}
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d.config = config
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return d.config, nil
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}
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// setConfig writes the sensor's config word to the device and returns the resulting config
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func (d *MCP9808) setConfig() error {
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return d.Bus.WriteWordToReg(address, regConfig, d.config)
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}
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// flipConfig bit sets (1, set = true) or clears (0, set = false) a bit within the config word
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func (d *MCP9808) flipConfigBit(val uint16, set bool) error {
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if set {
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d.config |= val
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} else {
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d.config &= ^val
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}
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return d.setConfig()
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}
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func (d *MCP9808) readConfigValue(val uint16) (bool, error) {
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config, err := d.Config()
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return !(config&(1<<val) == 0), err
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}
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// Hysteresis applies for decreasing temperature only (hot to cold) or as temperature
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// drifts below the specified limit.
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type Hysteresis uint8
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const (
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// Zero hysteresis represents 0 degrees Celsius of hysteresis compensation
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Zero Hysteresis = iota
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// Plus1pt5 hysteresis represents +1.5 degrees Celsius of hysteresis compensation
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Plus1pt5
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// Plus3pt0 hysteresis represents +3.0 degrees Celsius of hysteresis compensation
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Plus3pt0
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// Plus6pt0 hysteresis represents +6.0 degrees Celsius of hysteresis compensation
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Plus6pt0
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)
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// TempHysteresis - TUPPER and TLOWER Limit Hysteresis bits
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// 00 = 0°C (power-up default)
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// 01 = +1.5°C
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// 10 = +3.0°C
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// 11 = +6.0°C
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// The hysteresis applies for decreasing temperature only (hot to cold) or as temperature
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// drifts below the specified limit.
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func (d *MCP9808) TempHysteresis() (Hysteresis, error) {
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_, err := d.Config()
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return Hysteresis(d.config >> 9), err
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}
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// SetTempHysteresis - TUPPER and TLOWER Limit Hysteresis bits
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// 00 = 0°C (power-up default)
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// 01 = +1.5°C
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// 10 = +3.0°C
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// 11 = +6.0°C
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// The hysteresis applies for decreasing temperature only (hot to cold) or as temperature
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// drifts below the specified limit.
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// This bit can not be altered when either of the Lock bits are set (bit 6 and bit 7).
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// Thi s bit can be programmed in Shutdown mode.
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func (d *MCP9808) SetTempHysteresis(val Hysteresis) error {
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d.config = d.config - d.config&^(d.config>>9) + uint16(val)<<9
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return d.setConfig()
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}
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// ShutdownMode bit
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// 0 (false) = Continuous conversion (power-up default)
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// 1 (true) = Shutdown (Low-Power mode)
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// In shutdown, all power-consuming activities are disabled, though all registers can be written to or read.
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func (d *MCP9808) ShutdownMode() (bool, error) {
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return d.readConfigValue(configShutDown)
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}
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// SetShutdownMode bit
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// 0 (false) = Continuous conversion (power-up default)
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// 1 (true) = Shutdown (Low-Power mode)
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// In shutdown, all power-consuming activities are disabled, though all registers can be written to or read.
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// This bit cannot be set to ‘1’ when either of the Lock bits is set (bit 6 and bit 7). However, it can be
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// cleared to ‘0’ for continuous conversion while locked
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func (d *MCP9808) SetShutdownMode(set bool) error {
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return d.flipConfigBit(configShutDown, set)
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}
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// CriticalTempLock - TCRIT Lock bit
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// 0 (false) = Unlocked. TCRIT register can be written (power-up default)
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// 1 (true) = Locked. TCRIT register can not be written
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// When enabled, this bit remains set to ‘1’ or locked until cleared by an internal Reset
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func (d *MCP9808) CriticalTempLock() (bool, error) {
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return d.readConfigValue(configCriticalTempLock)
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}
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// SetCriticalTempLock - TCRIT Lock bit
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// 0 (false) = Unlocked. TCRIT register can be written (power-up default)
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// 1 (true) = Locked. TCRIT register can not be written
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// When enabled, this bit remains set to ‘1’ or locked until cleared by an internal Reset
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// This bit can be programmed in Shutdown mode.
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func (d *MCP9808) SetCriticalTempLock(locked bool) error {
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return d.flipConfigBit(configCriticalTempLock, locked)
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}
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// WindowTempLock - TUPPER and TLOWER Window Lock bit
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// 0 (false) = Unlocked; TUPPER and TLOWER registers can be written (power-up default)
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// 1 (true) = Locked; TUPPER and TLOWER registers can not be written
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// When enabled, this bit remains set to ‘1’ or locked until cleared by a Power-on Reset
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func (d *MCP9808) WindowTempLock() (bool, error) {
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return d.readConfigValue(configWindowTempLock)
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}
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// SetWindowTempLock - TUPPER and TLOWER Window Lock bit
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// 0 (false) = Unlocked; TUPPER and TLOWER registers can be written (power-up default)
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// 1 (true) = Locked; TUPPER and TLOWER registers can not be written
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// When enabled, this bit remains set to ‘1’ or locked until cleared by a Power-on Reset
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// This bit can be programmed in Shutdown mode.
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func (d *MCP9808) SetWindowTempLock(locked bool) error {
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return d.flipConfigBit(configWindowTempLock, locked)
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}
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// InterruptClear - Interrupt Clear bit
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// 0 (false) = No effect (power-up default)
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// 1 (true) = Clear interrupt output; when read, this bit returns to ‘0’
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func (d *MCP9808) InterruptClear() (bool, error) {
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return d.readConfigValue(configInterruptClear)
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}
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// SetInterruptClear - Interrupt Clear bit
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// 0 (false) = No effect (power-up default)
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// 1 (true) = Clear interrupt output; when read, this bit returns to ‘0’
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// This bit can not be set to ‘1’ in Shutdown mode, but it can be cleared after the device enters Shutdown
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// mode.
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func (d *MCP9808) SetInterruptClear(set bool) error {
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return d.flipConfigBit(configInterruptClear, set)
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}
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// AlertStatus Alert Output Status bit
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// 0 (false) = Alert output is not asserted by the device (power-up default)
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// 1 (true) = Alert output is asserted as a comparator/Interrupt or critical temperature output
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func (d *MCP9808) AlertStatus() (bool, error) {
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return d.readConfigValue(configAlertStatus)
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}
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// SetAlertStatus Alert Output Status bit
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// 0 (false) = Alert output is not asserted by the device (power-up default)
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// 1 (true) = Alert output is asserted as a comparator/Interrupt or critical temperature output
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// This bit can not be set to ‘1’ or cleared to ‘0’ in Shutdown mode. However, if the Alert output is configured
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// as Interrupt mode, and if the host controller clears to ‘0’, the interrupt, using bit 5 while the device
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// is in Shutdown mode, then this bit will also be cleared ‘0’.
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func (d *MCP9808) SetAlertStatus(set bool) error {
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return d.flipConfigBit(configAlertStatus, set)
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}
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// AlertControl - Alert Output Control bit
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// 0 (false) = Disabled (power-up default)
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// 1 (true) = Enabled
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func (d *MCP9808) AlertControl() (bool, error) {
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return d.readConfigValue(configAlertControl)
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}
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// SetAlertControl - Alert Output Control bit
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// 0 (false) = Disabled (power-up default)
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// 1 (true) = Enabled
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// This bit can not be altered when either of the Lock bits are set (bit 6 and bit 7).
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// This bit can be programmed in Shutdown mode, but the Alert output will not assert or deassert.
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func (d *MCP9808) SetAlertControl(set bool) error {
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return d.flipConfigBit(configAlertControl, set)
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}
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// AlertSelect - Alert Output Select bit
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// 0 (false) = Alert output for TUPPER, TLOWER and TCRIT (power-up default)
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// 1 (true) = TA > TCRIT only (TUPPER and TLOWER temperature boundaries are disabled)
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func (d *MCP9808) AlertSelect() (bool, error) {
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return d.readConfigValue(configAlertSelect)
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}
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// SetAlertSelect - Alert Output Select bit
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// 0 (false) = Alert output for TUPPER, TLOWER and TCRIT (power-up default)
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// 1 (true) = TA > TCRIT only (TUPPER and TLOWER temperature boundaries are disabled)
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// When the Alarm Window Lock bit is set, this bit cannot be altered until unlocked (bit 6).
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// This bit can be programmed in Shutdown mode, but the Alert output will not assert or deassert.
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func (d *MCP9808) SetAlertSelect(set bool) error {
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return d.flipConfigBit(configAlertSelect, set)
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}
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// AlertPolarity - Alert Output Polarity bit
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// 0 (false) = Active-low (power-up default; pull-up resistor required)
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// 1 (true) = Active-high
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func (d *MCP9808) AlertPolarity() (bool, error) {
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return d.readConfigValue(configAlertPolarity)
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}
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// SetAlertPolarity - Alert Output Polarity bit
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// 0 (false) = Active-low (power-up default; pull-up resistor required)
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// 1 (true) = Active-high
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// This bit cannot be altered when either of the Lock bits are set (bit 6 and bit 7).
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// This bit can be programmed in Shutdown mode, but the Alert output will not assert or deassert.
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func (d *MCP9808) SetAlertPolarity(set bool) error {
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return d.flipConfigBit(configAlertPolarity, set)
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}
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// AlertMode - Alert Output Mode bit
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// 0 (false) = Comparator output (power-up default)
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// 1 (true) = Interrupt output
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func (d *MCP9808) AlertMode() (bool, error) {
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return d.readConfigValue(configAlertMode)
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}
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// SetAlertMode - Alert Output Mode bit
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// 0 (false) = Comparator output (power-up default)
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// 1 (true) = Interrupt output
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// This bit cannot be altered when either of the Lock bits are set (bit 6 and bit 7).
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// This bit can be programmed in Shutdown mode, but the Alert output will not assert or deassert.
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func (d *MCP9808) SetAlertMode(set bool) error {
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return d.flipConfigBit(configAlertMode, set)
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}
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// Temperature contains the ambient temperature along with alert values.
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type Temperature struct {
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CelsiusDeg float64
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AboveCritical, AboveUpper, BelowLower bool
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}
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// readTempC reads from the reg temperature register and returns the current temperature value in celsius
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func (d *MCP9808) readTempC(reg byte) (float64, error) {
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temp, err := d.Bus.ReadWordFromReg(address, reg)
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if err != nil {
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return 0, err
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}
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return convertWordToTempC(temp), nil
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}
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func convertWordToTempC(temp uint16) float64 {
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return float64(int16(temp<<3)>>3) / 16
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}
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func (d *MCP9808) setTemp(reg byte, newTemp float64) error {
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return d.Bus.WriteWordToReg(address, reg, uint16(newTemp*16+2)&0x1ffc)
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}
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// AmbientTemp reads the current sensor value along with the flags denoting what boundaries the
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// current temperature exceeds.
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func (d *MCP9808) AmbientTemp() (*Temperature, error) {
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temp, err := d.Bus.ReadWordFromReg(address, regAmbientTemp)
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if err != nil {
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return nil, err
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}
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tempResult := &Temperature{
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AboveCritical: temp&0x8000 == 0x8000,
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AboveUpper: temp&0x4000 == 0x4000,
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BelowLower: temp&0x2000 == 0x2000}
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tempResult.CelsiusDeg = convertWordToTempC(temp)
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return tempResult, nil
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}
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// CriticalTemp reads the current temperature set in the critical temperature register.
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func (d *MCP9808) CriticalTemp() (float64, error) {
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return d.readTempC(regCriticalTemp)
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}
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// SetCriticalTemp when the temperature goes above the set value the alert will be
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// triggered if enabled. This has no effect if CriticalTempLock is set.
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func (d *MCP9808) SetCriticalTemp(newTemp float64) error {
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return d.setTemp(regCriticalTemp, newTemp)
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}
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// WindowTempUpper reads the current temperature set in the upper window temperature register.
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func (d *MCP9808) WindowTempUpper() (float64, error) {
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return d.readTempC(regUpperTemp)
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}
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// SetWindowTempUpper when the temperature goes above the set value the alert will be
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// triggered if enabled. This has no effect if WindowTempLock is set.
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func (d *MCP9808) SetWindowTempUpper(newTemp float64) error {
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return d.setTemp(regUpperTemp, newTemp)
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}
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// WindowTempLower reads the current temperature set in the lower window temperature register.
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func (d *MCP9808) WindowTempLower() (float64, error) {
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return d.readTempC(regLowerTemp)
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}
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// SetWindowTempLower when the temperature goes below the set value the alert will be
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// triggered if enabled. This has no effect if WindowTempLock is set.
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func (d *MCP9808) SetWindowTempLower(newTemp float64) error {
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return d.setTemp(regLowerTemp, newTemp)
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}
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// TempResolution reads the current temperature accuracy from the sensor (affects temperature read speed)
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// 0 - +/- .5 degrees C (~30ms)
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// 1 - +/- .25 degrees C (~65ms)
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// 2 - +/- .125 degrees C (~130ms)
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// 3 (default) - +/- .0625 degrees C (~250ms)
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type TempResolution uint8
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const (
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HalfC TempResolution = iota
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QuarterC
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EighthC
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SixteenthC
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)
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// TempResolution reads the temperature resolution from the sensor.
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func (d *MCP9808) TempResolution() (TempResolution, error) {
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res, err := d.Bus.ReadByteFromReg(address, regResolution)
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return TempResolution(res), err
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}
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// SetTempResolution writes a new temperature resolution to the sensor
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func (d *MCP9808) SetTempResolution(res TempResolution) error {
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return d.Bus.WriteByteToReg(address, regResolution, byte(res))
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}
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