mirror of
https://github.com/RobTillaart/Arduino.git
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158 lines
4.9 KiB
Markdown
158 lines
4.9 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/MAX520/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/MAX520/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MAX520/issues)
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[](https://github.com/RobTillaart/MAX520/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MAX520/releases)
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[](https://registry.platformio.org/libraries/robtillaart/MAX520)
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# MAX520
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Arduino library for MAX520/521 4/8 channel 8 bit DAC.
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## Description
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**Experimental**
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The MAX520 is a 4 channel 8 bit DAC. It has no output buffer amplifiers,
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giving it very low supply current.
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The output range of the MAX520 4 DACs depends on the 4 VREF inputs.
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You can have e.g. one from 0.0-5.0V one from 0.0-3.3V and two from 0.0-2.5V.
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The MAX521 is a 8 channel 8 bit DAC.
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The output range of the MAX521 8 DACs depends on the **FIVE** VREF inputs.
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OUT0..OUT3 use VREF0..VREF3 and OUT4..OUT7 all use VREF4.
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After calling **begin()** the user has to write the values per DAC or call **reset()**
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#### Related
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TODO other DAC libraries.
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## I2C
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#### I2C addresses
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| device | address pins | addresses |
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|:--------:|:--------------:|:--------------:|
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| MAX520 | 3 | 0x20 .. 0x27 |
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| MAX521 | 2 | 0x20 .. 0x23 |
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#### I2C Performance
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up to 400 KHz.
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#### I2C multiplexing
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Sometimes you need to control more devices than possible with the default
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address range the device provides.
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This is possible with an I2C multiplexer e.g. TCA9548 which creates up
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to eight channels (think of it as I2C subnets) which can use the complete
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address range of the device.
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Drawback of using a multiplexer is that it takes more administration in
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your code e.g. which device is on which channel.
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This will slow down the access, which must be taken into account when
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deciding which devices are on which channel.
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Also note that switching between channels will slow down other devices
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too if they are behind the multiplexer.
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- https://github.com/RobTillaart/TCA9548
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## Interface
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```cpp
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#include "MAX520.h"
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```
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**MAX520_INITIAL_VALUE** is a define 0xFF that can be set compile time or before
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the include of "MAX520.h" to overrule the default value used with the **begin()** call.
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#### Constructor
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- **MAX520(uint8_t deviceAddress = 0x20, TwoWire \*wire = &Wire)** Constructor with optional address, default 0x20,
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and the optional Wire interface as parameter.
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- **bool begin(uint8_t value = MAX520_INITIAL_VALUE)** set the initial value (default 0xFF) for the DACS.
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- **bool isConnected()** checks if the address set in the constructor or by **setAddress()** is visible on the I2C bus.
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- **bool setAddress(uint8_t deviceAddress)** sets the device address after construction.
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Can be used to switch between MAX520 modules runtime. Note this corrupts internal buffered values,
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so one might need to call **write()** again. Returns true if address can be found on I2C bus.
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- **uint8_t getAddress()** Returns the device address.
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- **uint8_t getChannels()** Returns the number of channels (4 or 8).
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#### Read and Write
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- **int write(uint8_t channel, uint8_t value)** writes value to chosen DAC.
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- **int write(uint8_t \* values)** writes to all DACs. user must take care that array is large enough (4/8).
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- **int read(uint8_t channel)** returns the last written value to chosen DAC. (from cache).
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#### Reset and power down
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- **int reset()** TODO what values?
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- **int powerDown()**
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- **int wakeUp()**
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TODO
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#### Miscellaneous
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- **int lastError()** returns the last error from the lib. (see .h file).
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## Error codes
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| name | value | description |
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|:-----------------------|:-------:|:--------------------------|
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| MAX520_OK | 0x00 | no error |
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| MAX520_CHANNEL_ERROR | 0x81 | channel nr out of range |
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| MAX520_I2C_ERROR | 0x82 | I2C communication error |
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## Future
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#### Must
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- improve documentation.
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- test with hardware
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- stabilize.
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#### Should
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- error handling
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#### Could
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#### Wont
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- add percentage API
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- add vref array + add voltage interface
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## Support
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If you appreciate my libraries, you can support the development and maintenance.
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Improve the quality of the libraries by providing issues and Pull Requests, or
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donate through PayPal or GitHub sponsors.
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Thank you,
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