Driver for I2C port multiplexer TCA9548A about modm HOT 3 CLOSED

Our I2C implementation needs to 🔥.

You'd have to implement the I2cMaster Transaction state machine on top of a I2c Transaction state machine and then provide 8 access ports to it.
You'd then wrap this in a shim layer like GpioExpander, so you can bind the Tca9548a object to a static type.

modm::Tca9548a<modm::platform::I2cMaster2> multiplexor;
using Port0 = modm::tca9548a::Multiplexor<multiplexor, 0>;

You'll most likely need to consider atomics at this point, since your Tca9548a implementation will have to be synced with its interrupts. Don't worry about AVRs for this, just use std::atomics and enable the driver only for Cortex-M.

from modm.

Sounds like fun, working on it!

from modm.

You'll most likely need to consider atomics at this point, since your Tca9548a implementation will have to be synced with its interrupts

Prefixing every I2C transaction with a transaction addressed to the PCA to select the channel seems to work. The underlying I2C master is queuing I2C transactions (and not reordering!) and sending them in order.

Todos:

• Make PCA9548 a template parameter to i2c_multiplexer.hpp
• Discuss the need for RF_CALL_BLOCKING
• Only return true in I2cMultiplexerChannel when both transactions were queued successfully.
• Use information of current channel to avoid idempotent channel selections.

from modm.