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223 lines
7.5 KiB
Markdown
223 lines
7.5 KiB
Markdown
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[](https://github.com/RobTillaart/MAX14661/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/MAX14661/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/MAX14661/issues)
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[](https://github.com/RobTillaart/MAX14661/blob/master/LICENSE)
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[](https://github.com/RobTillaart/MAX14661/releases)
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[](https://registry.platformio.org/libraries/robtillaart/MAX14661)
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# MAX14661
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Arduino library for MAX14661 multiplexer with I2C interface.
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## Description
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The MAX14661 multiplexer is a 16 x 2 channel multiplexer.
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It has 2 lines A and B which can be
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connected up to 16 A lines and 16 B lines.
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The library provides 4 kinds of interfaces (see below)
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- **PAIR** switch A and B in pairs
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- **SHADOW** use a shadow register to set all simultaneously.
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- **MUX** open channels exclusively.
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- **FULL** control all as you like.
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Mixing these interfaces is allowed but definitely not advised as
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especially the **PAIR** interface assumes that A and B selections
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are kept in sync.
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So depending on your application choose the interface you want to use.
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The MAX14661 device can be controlled by SPI or I2C.
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This library implements the I2C interface.
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#### I2C address
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The I2C address can be adjusted by 2 address lines A0 and A1.
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Addresses go from 0x4C (76) .. 0x4F (79). See table 3 datasheet.
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This implies you may have up to 4 MAX14661 multiplexers on one I2C bus.
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If you need more, consider a TCA9548.
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According to the datasheet the I2C Serial-Clock Frequency is max 400 kHz.
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(SPI can do 10 MHz)
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#### Related
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- https://github.com/RobTillaart/TCA9548 specific I2C multiplexer.
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- https://github.com/RobTillaart/HC4067 1x16 channel multiplexer.
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- https://github.com/RobTillaart/HC4051 1x8 channel multiplexer.
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- https://github.com/RobTillaart/HC4052 2x4 channel multiplexer.
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- https://github.com/RobTillaart/HC4053 2x3 channel multiplexer.
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## Interface
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```cpp
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#include "MAX14661.h"
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```
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#### Constructor
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- **MAX14661(deviceAddress, TwoWire \*wire = &Wire)** Constructor with device address,
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and optional the Wire interface as parameter.
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- **bool begin()** initializes the wire interface.
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- **bool begin(sda, scl)** idem, for the ESP32 where one can choose the I2C pins.
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- **bool isConnected()** checks if the device address is visible on the I2C bus.
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#### PAIR interface
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The functions in this interface part all work symmetrical on the A and B line.
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They are managed as a PAIR. So this is ideal e.g. to multiplex an I2C bus or
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a Serial TX/RX pair line.
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The interface allows to have multiple lines A/B open in parallel.
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// open ==> connect
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- **bool openChannel(uint8_t channel)** connects A/B to chosen channel.
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- **bool closeChannel(uint8_t channel)** disconnects channel from A/B.
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- **bool isOpenChannel(uint8_t channel)** returns true if connected to A/B.
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- **void openAllChannels()** connects all channels.
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- **void closeAllChannels()** disconnects all channels.
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- **void setChannels(uint16_t mask)** connect multiple channels with a bit mask.
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- **uint16_t getChannels()** returns a bit mask of the channels connected.
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Note:
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**setChannels(mask)** is the only way to set channels at the very same moment
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in the **PAIR** interface.
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#### SHADOW interface
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Experimental - to be tested.
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The SHADOW interface allows one to prepare which channels should be selected,
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and activate them all at once.
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- **bool shadowClear()** clears all shadow registers.
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- **void activateShadow()** write all shadow registers to the direction
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registers of A and B at once.
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Prepare multiple channels at once. This is way faster than per channel.
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- **bool setShadowChannelMaskA(uint16_t mask)** write all channels at once.
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- **uint16_t getShadowChannelMaskA()** read shadow registers.
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- **bool setShadowChannelMaskB(uint16_t mask)** write all channels at once.
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- **uint16_t getShadowChannelMaskB()** read shadow registers.
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Prepare per channel.
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- **bool isOpenShadowChannelA(uint8_t channel)** read status of specific channel in shadow registers.
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- **void openShadowChannelA(uint8_t channel)** prepare a specific channel to open.
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- **void closeShadowChannelA(uint8_t channel)** prepare a specific channel to close.
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- **bool isOpenShadowChannelB(uint8_t channel)** read status of specific channel in shadow registers.
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- **void openShadowChannelB(uint8_t channel)** prepare a specific channel to open.
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- **void closeShadowChannelB(uint8_t channel)** prepare a specific channel to close.
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Note: there is no command that sets both A and B simultaneously.
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#### MUX interface
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The MUX interface allows one channel (0..15) to be open at a time.
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- **void MUXA(uint8_t channel)** if channel < 16 only that channel will be selected.
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All other values will select no channel.
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- **uint8_t getMUXA()** returns the selected channel.
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255 means none selected.
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- **void MUXB(uint8_t channel)** if channel < 16 only that channel will be selected.
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All other values will select no channel.
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- **uint8_t getMUXB()** returns the selected channel.
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255 means none selected.
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#### FULL CONTROL interface
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Full control per channel, any combination is possible.
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Use with care as these can interfere e.g. with the PAIR interface.
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All functions return false if channel > 15.
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- **bool openA(uint8_t channel)** idem
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- **bool openB(uint8_t channel)** idem
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- **bool closeA(uint8_t channel)** idem
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- **bool closeB(uint8_t channel)** idem
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#### LOW LEVEL CONTROL interface
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Check datasheet for the meaning of and the values in the registers.
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- **uint8_t readRegister(uint8_t reg)** read low level device register.
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- **int writeRegister(uint8_t reg, uint8_t value)** write value to device register.
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#### Error handling
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- **int lastError()** returns the last error, limited to low level I2C for now.
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to be elaborated / implemented(see future)
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| Define | value | notes |
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|:-----------------------|:-------:|:-------:|
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| MAX14661_OK | 0x00 |
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| MAX14661_ERR_I2C | 0x80 | not implemented yet |
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| MAX14661_ERR_CHANNEL | 0x81 | not implemented yet |
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## Operation
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See examples
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## Future
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#### Must
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- improve documentation
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#### Should
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- test behaviour.
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- write unit tests.
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- implement error handling.
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- use an internal mode to see which of the three interfaces is used
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consequently or not?
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- MAX14661_ERR_ADDRESS ?
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#### Could
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- optimize low level bit set/clr/get read/write 2 bytes at once.
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- test I2C communication speed.
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- 100- 400 kHz and up.
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- measure performance.
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- cache direct registers. (fast response).
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- **ShutDown()** SD pin. for low power datasheet p.15
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- document it.
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- implement.
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#### Wont
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- SPI interface.
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- separate (derived ?) class
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- initial values parameter for begin()?
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- depends on interface (PAIR MUX SHADOW) used, ambiguous.
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- ==> user task.
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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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