GY-63_MS5611/libraries/AD56X8

AD56X8

Experimental Library for the AD56X8 series digital analog convertor.

NOTE: not yet tested, TODO buy hardware.

Feedback, issues, improvements are welcome. Please file an issue on GitHub.

Description

The AD56X8 is an 8 channel DAC convertor, that has 12, 14 or 16 bit accuracy. Furthermore it is available in 2.5 V and 5.0 V version, see table below.

The device allows to set the outputs directly, or prepare them and update them simultaneously (Latch DAC).

type	output	resolution	power up
AD5668-1	2.5 V	16 bit	0.0 V
AD5648-1	2.5 V	14 bit	0.0 V
AD5628-1	2.5 V	12 bit	0.0 V
AD5668-3	5.0 V	16 bit	2.5 V
AD5668-2	5.0 V	16 bit	0.0 V
AD5648-2	5.0 V	14 bit	0.0 V
AD5628-2	5.0 V	12 bit	0.0 V

The library is usable but not functional complete yet. At least it lacks support for:

• RESET pin,
• LDAC pin,
• VREF pin.
• other points mentioned in future section below.

Links

This library is partly inspired by https://github.com/bobhart/AD5668-Library, kudo's to Bob! Discussed here - https://forum.arduino.cc/t/new-library-for-the-ad5668-dac/340393

Furthermore it has the SPI part from https://github.com/RobTillaart/MCP_DAC a.o.

Some differences between this library and Bob Harts. This library

• caches the values of all channels, so they can be read back.
• has derived classes for every specific type DAC. This allows value range checking in the future. Not Implemented Yet.
• caches the LDAC mask, so it can be read back and updated.
• has extended (ESP32) SPI interface (similar and tested with MCP_DAC)
• allows to set SPI-speed.
• has faster software SPI transfer, on ESP32 this rivals HW SPI.
• MIT license instead of GNU v3

Interface

#include "AD56X8.h"

Base class

Should not be used to instantiate a device as the derived types have correct number of bits.

• AD56X8(uint8_t slaveSelect) constructor base class, sets HW SPI. Uses default a 16 bit interface. Sets internal values to zero.
• AD56X8(uint8_t spiData, uint8_t spiClock, uint8_t slaveSelect) constructor, sets SW SPI. Uses default a 16 bit interface. Sets internal values to zero.
• begin() initializes the SPI and sets internal state.

Set DAC

• bool setValue(uint8_t channel, uint16_t value) set value to the output immediately, effectively a prepare + update in one call. Returns false if channel out of range.
• uint16_t getValue(uint8_t channel) returns set OR prepared value. At power up the DAC's will be reset to 0 V except the AD5668-3 (2.5V).
• bool prepareChannel(uint8_t channel, uint16_t value) prepares the value for a channel. Returns false if channel out of range.
• bool updateChannel(uint8_t channel) writes the prepared value to ADC. Returns false if channel out of range.
• void updateAllChannels() writes all prepared channels to their ADC simultaneously by applying a SW latch pulse (LDAC).

NOte: the valid range of value is not checked by the library.

LDAC

The AD56X8 has an LDAC register with one bit per channel. This is to configure which channels are updated simultaneously. Read datasheet for details.

• void setLDACmask(uint8_t mask = 0x00) sets 8 channels with one call by using a bit mask. Default value 0x00 clears all channels.
• uint8_t getLDACmask() return the current (cached) LDAC bit mask, default = 0x00.
• bool inLDACmask(uint8_t channel) returns true if a channel is in the current LDAC bit mask. Returns also false if channel is out of range.

Powermode

• bool setPowerMode(uint8_t powerDownMode, uint8_t mask = 0x00) powerDownMode = 0..3. Default is setting the channels to PWR_NORMAL. Returns false if powerDownMode is out of range.

mode	define
0x00	AD56X8_PWR_NORMAL
0x01	AD56X8_PWR_1K
0x02	AD56X8_PWR_100K
0x03	AD56X8_PWR_TRI

Misc

• void reset() software reset.
• bool setClearCode(uint8_t CCmode) Set the startup value. CCmode = 0..3, see table below. Returns false if mode out of range.

mode	define	notes
0x00	AD56X8_CC_0000
0x01	AD56X8_CC_8000
0x02	AD56X8_CC_FFFF
0x03	AD56X8_CC_NOP	do not use => Read datasheet.

SPI

• void setSPIspeed(uint32_t speed) sets SPI clock in Hz, please read datasheet of the ADC first to get optimal speed.
• uint32_t getSPIspeed() gets current speed in Hz.
• bool usesHWSPI() returns true if HW SPI is used.

SPI ESP32 specific

("inherited" from MPC_DAC library)

• void selectHSPI() in case hardware SPI, the ESP32 has two options HSPI and VSPI.
• void selectVSPI() see above.
• bool usesHSPI() returns true if HSPI is used.
• bool usesVSPI() returns true if VSPI is used.

The selectVSPI() or the selectHSPI() needs to be called BEFORE the begin() function.

(experimental)

• void setGPIOpins(uint8_t clk, uint8_t miso, uint8_t mosi, uint8_t select) overrule GPIO pins of ESP32 for hardware SPI. needs to be called AFTER the begin() function.

Note: earlier experiments shows that on a ESP32 SW-SPI is equally fast as HW-SPI and in fact a bit more stable. 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.

Derived classes (preferred use)

The parameters for the specific constructors are identical to the base class.

• AD5668_3(..) constructor, 16 bit. Starts up at midscale = 32768.
• AD5668(..) constructor, 16 bit.
• AD5648(..) constructor, 14 bit.
• AD5628(..) constructor, 12 bit.

Operation

The examples (should) show the basic working of the functions. Note that the library is not tested with hardware yet. (based upon datasheet)

Future

Must

• update and improve documentation
• get test hardware
• test the library
• write unit test
• check TODO's in code

Should

• write examples
  • get/setValue
  • LDAC
  • power mode
• support for RESET pin
• support for LDAC pin
• support for EXTERNAL VREF
• investigate value range checking for AD5648 and AD5628
  • now setValue() returns false if value > max,
  • should value be clipped instead?
• voltage interface(?)
  • convenient.
• bool loadLDAC() TODO?
• investigate different type for AD5668_3 (as it does midscale)

Could

• CCmode + reset implies start value for getValue(ch)
  • is this implementable? costs?