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217 lines
7.4 KiB
Markdown
217 lines
7.4 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/AD56X8/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/AD56X8/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/AD56X8/blob/master/LICENSE)
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[](https://github.com/RobTillaart/AD56X8/releases)
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# AD56X8
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Experimental Library for the AD56X8 series digital analog convertor.
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NOTE: not yet tested, TODO buy hardware.
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Feedback, issues, improvements are welcome.
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Please file an issue on GitHub.
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## Description
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The AD56X8 is an 8 channel DAC convertor, that has 12, 14 or 16 bit accuracy.
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Furthermore it is available in 2.5 V and 5.0 V version, see table below.
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The device allows to set the outputs directly, or prepare them and update them simultaneously (Latch DAC).
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| type | output | resolution | power up |
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|:---------|:--------:|:----------:|:---------:|
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| AD5668-1 | 2.5 V | 16 bit | 0.0 V |
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| AD5648-1 | 2.5 V | 14 bit | 0.0 V |
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| AD5628-1 | 2.5 V | 12 bit | 0.0 V |
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| AD5668-3 | 5.0 V | 16 bit | **2.5 V** |
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| AD5668-2 | 5.0 V | 16 bit | 0.0 V |
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| AD5648-2 | 5.0 V | 14 bit | 0.0 V |
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| AD5628-2 | 5.0 V | 12 bit | 0.0 V |
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The library is usable but not functional complete yet.
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At least it lacks support for:
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- RESET pin,
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- LDAC pin,
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- VREF pin.
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- other points mentioned in future section below.
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## Links
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This library is partly inspired by https://github.com/bobhart/AD5668-Library, kudo's to Bob!
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Discussed here - https://forum.arduino.cc/t/new-library-for-the-ad5668-dac/340393
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Furthermore it has the SPI part from https://github.com/RobTillaart/MCP_DAC a.o.
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Some differences between this library and Bob Harts. This library
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- caches the values of all channels, so they can be read back.
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- has derived classes for every specific type DAC.
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This allows value range checking in the future. Not Implemented Yet.
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- caches the LDAC mask, so it can be read back and updated.
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- has extended (ESP32) SPI interface (similar and tested with MCP_DAC)
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- allows to set SPI-speed.
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- has faster software SPI transfer, on ESP32 this rivals HW SPI.
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- MIT license instead of GNU v3
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## Interface
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```cpp
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#include "AD56X8.h"
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```
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#### Base class
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Should not be used to instantiate a device as the derived types have correct number of bits.
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- **AD56X8(uint8_t slaveSelect)** constructor base class, sets HW SPI.
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Uses default a 16 bit interface.
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Sets internal values to zero.
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- **AD56X8(uint8_t spiData, uint8_t spiClock, uint8_t slaveSelect)** constructor, sets SW SPI.
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Uses default a 16 bit interface.
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Sets internal values to zero.
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- **begin()** initializes the SPI and sets internal state.
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#### Set DAC
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- **bool setValue(uint8_t channel, uint16_t value)** set value to the output immediately, effectively a prepare + update in one call.
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Returns false if channel out of range.
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- **uint16_t getValue(uint8_t channel)** returns set OR prepared value.
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At power up the DAC's will be reset to 0 V except the AD5668-3 (2.5V).
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- **bool setPercentage(uint8_t channel, float percentage)** idem.
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- **float getPercentage(uint8_t channel)** idem.
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- **bool prepareChannel(uint8_t channel, uint16_t value)** prepares the value for a channel.
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Returns false if channel out of range.
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- **bool updateChannel(uint8_t channel)** writes the prepared value to ADC.
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Returns false if channel out of range.
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- **void updateAllChannels()** writes all prepared channels to their ADC simultaneously by applying a SW latch pulse (LDAC).
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NOte: the valid range of **value** is not checked by the library.
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#### LDAC
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The AD56X8 has an LDAC register with one bit per channel.
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This is to configure which channels are updated simultaneously.
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Read datasheet for details.
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- **void setLDACmask(uint8_t mask = 0x00)** sets 8 channels with one call by using a bit mask. Default value 0x00 clears all channels.
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- **uint8_t getLDACmask()** return the current (cached) LDAC bit mask, default = 0x00.
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- **bool inLDACmask(uint8_t channel)** returns true if a channel is in the current LDAC bit mask.
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Returns also false if channel is out of range.
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#### Powermode
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- **bool setPowerMode(uint8_t powerDownMode, uint8_t mask = 0x00)** powerDownMode = 0..3.
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Default is setting the channels to **PWR_NORMAL**.
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Returns false if powerDownMode is out of range.
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| mode | define |
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|:------:|:-------------------|
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| 0x00 | AD56X8_PWR_NORMAL |
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| 0x01 | AD56X8_PWR_1K |
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| 0x02 | AD56X8_PWR_100K |
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| 0x03 | AD56X8_PWR_TRI |
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#### Misc
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- **void reset()** software reset.
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- **bool setClearCode(uint8_t CCmode)** Set the startup value.
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CCmode = 0..3, see table below.
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Returns false if mode out of range.
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| mode | define | notes |
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|:------:|:-------------------|:--------|
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| 0x00 | AD56X8_CC_0000 |
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| 0x01 | AD56X8_CC_8000 |
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| 0x02 | AD56X8_CC_FFFF |
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| 0x03 | AD56X8_CC_NOP | do not use => Read datasheet.
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#### SPI
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- **void setSPIspeed(uint32_t speed)** sets SPI clock in **Hz**, please read datasheet
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of the ADC first to get optimal speed.
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- **uint32_t getSPIspeed()** gets current speed in **Hz**.
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- **bool usesHWSPI()** returns true if HW SPI is used.
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#### SPI ESP32 specific
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("inherited" from MPC_DAC library)
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- **void selectHSPI()** in case hardware SPI, the ESP32 has two options HSPI and VSPI.
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- **void selectVSPI()** see above.
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- **bool usesHSPI()** returns true if HSPI is used.
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- **bool usesVSPI()** returns true if VSPI is used.
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The **selectVSPI()** or the **selectHSPI()** needs to be called
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BEFORE the **begin()** function.
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(experimental)
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- **void setGPIOpins(uint8_t clk, uint8_t miso, uint8_t mosi, uint8_t select)**
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overrule GPIO pins of ESP32 for hardware SPI. needs to be called AFTER the **begin()** function.
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Note: earlier experiments shows that on a ESP32 SW-SPI is equally fast as HW-SPI and in fact a bit more stable.
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The SW pulses are a bit slower than the HW pulses and therefore more square. The HW-SPI has some overhead SW-SPI hasn't.
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### Derived classes (preferred use)
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The parameters for the specific constructors are identical
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to the base class.
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- **AD5668_3(..)** constructor, 16 bit.
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Starts up at **midscale = 32768**.
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- **AD5668(..)** constructor, 16 bit.
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- **AD5648(..)** constructor, 14 bit.
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- **AD5628(..)** constructor, 12 bit.
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## Operation
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The examples (should) show the basic working of the functions.
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Note that the library is not tested with hardware yet.
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(based upon datasheet)
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## Future
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#### Must
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- update and improve documentation
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- get test hardware
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- test the library
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- write unit test
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- check TODO's in code
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#### Should
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- write examples
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- LDAC
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- power mode
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- support for RESET pin
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- support for LDAC pin
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- support for EXTERNAL VREF
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- investigate value range checking for AD5648 and AD5628
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- now setValue() returns false if value > max,
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- should value be clipped instead?
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- **bool loadLDAC()** TODO?
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- investigate different type for AD5668_3 (as it does midscale)
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#### Could
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- CCmode + reset implies start value for getValue(ch)
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- is this implementable? costs?
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