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arduino-libraries / Arduino_MachineControl

GNU Lesser General Public License v2.1
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Allow full bank reads from IO expander #75

Closed mattbue closed 2 years ago

mattbue commented 2 years ago

Hi all,

i'm using the Arduino Machine Control to capture signals from sensors on production machines and send them via USB/serial port to a PC where the data is logged. Usually only the 8 digital inputs are needed. Since i want to get the signals every millisecond, i realized that reading the signals one by one using digital_inputs.read(...) takes too much time. Instead i added methods to the ArduinoIOExpanderClass with which i can use TCA6424A::readAll(...) and TCA6424A::readBank(...).

I made some simple measurements by comparing the value comparing from micros() before and after running the "read" methods. I also changed the I2C clock frequency.

1. Reading channel 0 to 7 one by one @100kHz: 3588 us 2. Reading channel 0 to 7 one by one @400kHz: 1337 us 3. Reading bank 0 @100kHz: 452 us 4. Reading bank 0 @400kHz: 169 us 5. Reading bank 0, 1 & 2 one by one @100kHz: 1345 us 6. Reading bank 0, 1 & 2 one by one @400kHz: 501 us 7. Reading all banks @100kHz: 653 us 8. Reading all banks @400kHz: 242 us

By running I2C at 400kHz and using the readBank(...) method I get all 8 bits of bank 0 within ~170 us which is sufficient for me.

Would it be possible to add such methods to ArduinoIOExpanderClass to have them available "out of the box"?

Best regards matt

pnndra commented 2 years ago

@mattbue i would suggest you open a PR with your changes.

manchoz commented 2 years ago

Hi @mattbue, please, check #86

manchoz commented 2 years ago

Hi @per1234, I think we can close this issue: feature has been implemented and tested and there is no feedback or activity.

per1234 commented 2 years ago

Thanks @manchoz! I'm closing this as resolved by https://github.com/arduino-libraries/Arduino_MachineControl/pull/86