Arduino library for an LTC2991 temperature and voltage control IC.
Experimental - not tested myself, (no hardware)
LTC2991 is an experimental library for the LTC2991 IC which is typically used to monitor temperature and voltage. It also has a PWM out to control e.g. a fan.
The IC supports normal voltage measurement (8 lines), differential voltage measurements (4 pairs) and temperature measurements (4 pairs). These can be combined in a mix. As the IC has only 8 inputs available one has to choose what.
Read the datasheet for the details.
From datasheet - table 1
The address template is 0 1 0 0 - 1 A2 A1 A0 ==> 0x48 if all address pins are grounded,
| ADR0 | ADR1 | ADR2 | address |
|---|---|---|---|
| 0 | 0 | 0 | 0x48 |
| 1 | 0 | 0 | 0x49 |
| 0 | 1 | 0 | 0x4A |
| 1 | 1 | 0 | 0x4B |
| 0 | 0 | 1 | 0x4C |
| 1 | 0 | 1 | 0x4D |
| 0 | 1 | 1 | 0x4E |
| 1 | 1 | 1 | 0x4F |
#include "LTC2991.h"- LTC2991(const uint8_t address, TwoWire *wire = Wire) The address is 0x48..0x4F depending on the address pins. The library does not check the range.
- bool begin() UNO ea. initializes the class.
Returns true if the LTC2991 address is on the I2C bus.
Note: do call Wire.begin() before begin() - bool isConnected() Returns true if the LTC2991 address is on the I2C bus.
- uint8_t getAddress() Returns the address set in the constructor.
- bool new_data(uint8_t channel) true if there is a new external measurement available. This can be a voltage or a temperature measurement.
- bool new_temperature() true if there is a new internal temperature measurement available.
- bool new_voltage() true, if there is a new internal voltage measurement available.
- bool is_busy() true if the sensor is converting...
The following functions work on pairs:
| n | selected |
|---|---|
| 1 | V1 V2 T1 |
| 2 | V3 V4 T2 |
| 3 | V5 V6 T3 |
| 4 | V7 V8 T4 |
- void trigger_conversion(uint8_t n) wrapper around enable(n, true), better naming.
- void trigger_conversion_all() triggers conversions for all 4 channels/pairs.
- void enable(uint8_t n, bool enable) enable or disable an external line. disable can be used to stop the repeat mode.
- bool is_enabled(uint8_t n) idem
- void enable_filter(uint8_t n, bool enable) enable filter - not investigated.
- bool is_enabled_filter(uint8_t n) idem.
- void set_Kelvin(uint8_t n) sets temperature mode to Kelvin, implicit set_mode_temperature().
- void set_Celsius(uint8_t n) sets temperature mode to Celsius, implicit set_mode_temperature.
- void set_temp_scale(uint8_t n, bool Kelvin = true) used to switch between Kelvin and Celsius.
- char get_temp_scale(uint8_t n) returns 'K' or 'C'.
- void set_mode_temperature(uint8_t n) sets operational mode.
- void set_mode_voltage_differential(uint8_t n) sets operational mode.
- void set_mode_voltage_normal(uint8_t n) sets operational mode.
- uint8_t get_operational_mode(uint8_t n) returns operational mode.
- uint8_t get_differential_mode(uint8_t n) returns differential flag.
- float get_value(uint8_t channel) channel = 1..8; depending on the operational mode it returns the temperature or the (differential) voltage.
- void enable_Tintern_Vcc(bool enable) enable internal temperature measurements.
- bool is_enabled_Tintern_Vcc() idem.
- void enable_filter_Tintern(bool enable) enable filter - not investigated
- bool is_enabled_filter_Tintern()
- void set_Kelvin_Tintern() use Kelvin.
- void set_Celsius_Tintern() use Celsius.
- void set_temp_scale_Tintern(bool Kelvin = true) Obsolete?.
- char get_temp_scale_Tintern() returns 'K' or 'C'.
- float get_Tintern() returns the internal temperature.
- float get_VCC() returns the internal voltage.
- void set_acquisition_repeat() set continuous measurement mode.
- void set_acquisition_single() set single shot mode. Note that before a measurement is made one needs to call trigger_conversion(n) or trigger_conversion_all().
- uint8_t get_acquisition_mode() return mode set (0,1).
- 1 = repeat
- 0 = single
- void set_PWM(uint16_t value = 0) value is 0..511.
- void set_PWM_fast(uint16_t value = 0) value is 0..511, less resolution (256 steps).
- uint16_t get_PWM() returns the value from the PWM register, when using PWM_fast this can differ 1.
- void invert_PWM(bool invert) idem.
- bool is_inverted_PWM() idem.
- void enable_PWM(bool enable) idem.
- bool is_enabled_PWM() idem.
No data available yet. To be measured when hardware is available... if you happen to have performance figures, please share them in an issue.
- get hardware to test
- improve documentation (a lot)
- error handling
- unit tests if possible?
- remove magic numbers / masks from code
- some defines prepared in CPP file => to .h
- cache registers (which) or ?
- cache a number of flags to speed up retrieving data
- optimizations
- code / math
- optimize multi-byte read / write
- void disable_PWM() convenience,
- enable_PWM(bool) default true flag
- void LTC2991::enable(uint8_t mask) faster to set multiple.
- redo naming of some functions?
- first get hands on experience.
- add Fahrenheit
- do low level in Kelvin and convert to KFC as needed.
- would simplify get_value
- need an enum
- would interface # functions increase too much?
- == > Users can do this conversion.
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