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134 lines
4.7 KiB
Markdown
134 lines
4.7 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/TCA9548/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/TCA9548/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/TCA9548/blob/master/LICENSE)
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[](https://github.com/RobTillaart/TCA9548/releases)
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# TCA9548
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Arduino Library for TCA9548 I2C multiplexer.
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## Description
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Library for the TCA9548 and TCA9548a (PCA9548, PCA9548a) I2C multiplexer.
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The library allows you to enable 0 to 7 I2C channels (ports) uniquely or simultaneously.
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This is especially useful if you have multiple devices/sensors that have a fixed address,
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or you have address conflicts between I2C devices
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**Warning**
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The library is not tested extensively.
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I2C address of the device itself is 0x70 .. 0x77.
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This address may not be used on any of the I2C channels of course.
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The library caches the channels enabled, and if a channel is enabled,
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it will not be enabled again (low level) to optimize performance.
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#### Compatible devices
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This library is expected to work for the PCA9548(a) too as the TCA is pin compatible newer version.
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| Device | Tested | Notes |
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|:-----------|:--------:|:-------:|
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| TCA9548s | n |
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| PCA9548 | n | see links below |
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| PCA9548a | n |
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There are however small differences, check the datasheets to see the details.
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- [difference TCA PCA](https://e2e.ti.com/support/interface-group/interface/f/interface-forum/815758/faq-what-is-the-difference-between-an-i2c-device-with-the-family-name-pca-and-tca)
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- https://electronics.stackexchange.com/questions/209616/is-nxps-pca9548a-compatible-with-tis-tca9548a
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- https://www.nxp.com/docs/en/application-note/AN262.pdf
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## Interface
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```cpp
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#include "TCA9548.h"
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```
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#### Constructor
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- **TCA9548(const uint8_t deviceAddress, TwoWire \*wire = &Wire)** Constructor.
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deviceAddress = 0x70 .. 0x77, wire = Wire or WireN.
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- **bool begin(uint8_t dataPin, uint8_t clockPin, uint8_t mask = 0x00)** Set I2C pins for ESP32.
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Set mask of channels to be enabled, default all disabled.
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- **bool begin(uint8_t mask = 0x00)** set mask of channels to be enabled, default all disabled.
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- **bool isConnected()** returns true if address of the multiplexer is found on I2C bus.
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#### Find device
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- **bool isConnected(uint8_t address)** returns true if arbitrary address is found on I2C bus.
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This can be used to verify a certain device is available (or not) on an enabled channel.
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#### Channel functions
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All "channel functions" return true on success.
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- **bool enableChannel(uint8_t channel)** enables channel 0 .. 7 non-exclusive.
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Multiple channels can be enabled in parallel.
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- **bool disableChannel(uint8_t channel)** disables channel 0 .. 7.
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Will not disable other channels.
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- **bool selectChannel(uint8_t channel)** enables a single channel 0 .. 7 exclusive.
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All other channels will be disabled in the same call, so not before or after.
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- **bool isEnabled(uint8_t channel)** returns true if the channel is enabled.
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- **bool disableAllChannels()** fast way to disable all.
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- **bool setChannelMask(uint8_t mask)** enables 0 or more channels simultaneously with a bit mask.
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- **uint8_t getChannelMask()** reads back the bit mask of the channels enabled.
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#### Reset
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- **void setResetPin(uint8_t resetPin)** sets the pin to reset the chip. (Not tested)
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- **void reset()** trigger the reset pin.
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- **int getError()** returns the last I2C error.
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#### Forced IO
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When forced IO is set all writes and read - **getChannelMask()** - will go to the device.
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If the flag is set to false it will cache the value of the channels enabled.
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This will result in more responsive / faster calls.
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Note that writes are only optimized if the channels are already set.
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- **void setForced(bool forced = false)** set forced write, slower but more robust.
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- forced == false == fast mode (default).
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- forced == true == robust mode.
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- **bool getForced()** returns set flag.
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## Future
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#### Must
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- improve documentation.
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- improve error handling
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#### Should
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- add examples
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- test test and test
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- write unit test
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- create derived classes for compatible devices
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#### Could
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- set an "always enabled" mask (have to investigate the consequences)
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- verify channel in range
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- e.g. **bool enableChannel(uint8_t channel)**, disable(), select()
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#### Wont
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