GY-63_MS5611/libraries/DAC8551/README.md

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# DAC8551

Arduino library for DAC8501 DAC8531, DAC8550, DAC8551 SPI Digital Analog Convertor.


## Description

The DAC8551 is a SPI based 16 bit DAC with one channel.

The DAC8501, DAC8531 and DAC8550 are drop in compatible 
They all have classed derived 1 to 1 from DAC8551.

**Warning** this library is not tested extensively.


## Interface

### Core

- **DAC8501(uint8_t slaveSelect)** Constructor for DAC8501 with hardware SPI,
- **DAC8531(uint8_t slaveSelect)** Constructor for DAC8531 with hardware SPI,
- **DAC8550(uint8_t slaveSelect)** Constructor for DAC8550 with hardware SPI,
- **DAC8551(uint8_t slaveSelect)** Constructor for DAC8551 with hardware SPI,
since 0.2.0 the slaveSelect pin needs to be defined.
- **DAC8501(uint8_t spiData, uint8_t spiClock, uint8_t slaveSelect)** Constructor for the software SPI
- **DAC8531(uint8_t spiData, uint8_t spiClock, uint8_t slaveSelect)** Constructor for the software SPI
- **DAC8550(uint8_t spiData, uint8_t spiClock, uint8_t slaveSelect)** Constructor for the software SPI
- **DAC8551(uint8_t spiData, uint8_t spiClock, uint8_t slaveSelect)** Constructor for the software SPI
- **void begin()** initializes all pins to default state
- **void setValue(uint16_t value)** set the value of the channel to 0 - 65535
- **uint16_t getValue()** returns the last value written.


### Hardware SPI

To be used only if one needs a specific speed.

- **void setSPIspeed(uint32_t speed)** set SPI transfer rate.
- **uint32_t getSPIspeed()** returns SPI transfer rate.
- **bool usesHWSPI()** returns true if HW SPI is used.


### ESP32 specific

- **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.


### Power down

check datasheet for details.

- **void setPowerDown(uint8_t powerDownMode)** sets power down mode. 0 - 3.
- **uint8_t getPowerDownMode()** returns last written mode.

| Power down mode            | Value |
|:---------------------------|:-----:|
| DAC8551_POWERDOWN_NORMAL   |   0   |
| DAC8551_POWERDOWN_1K       |   1   |
| DAC8551_POWERDOWN_100K     |   2   |
| DAC8551_POWERDOWN_HIGH_IMP |   3   |


Note: DAC8501, DAC8531 and DAC8550 uses the same constants.


## Operation

See examples

**demo_hw_spi.ino**
- write a sawtooth to channel A followed by a sinus 
- uses HW SPI

**demo_sw_spi.ino**
- write a sawtooth to channel A followed by a sinus 
- uses SW SPI

**demo_powerdown.ino**
- idem


## Future

- testing
- verify replacement chips