Hello everyone,
do you think that I can chain the pimidi and a LCD 2004 with a I2C interface ? they are both sharing the same pins. And the I2C protocol supports daisy chains. I don’ t see blocking point here but I might be wrong…
Thanks
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Yes, it should not be a problem - just ensure that they use different I²C addresses and that there’s no GPIO conflict, see the sel rotary switch documentation here and the GPIO pins used by Pimidi.
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A nice tool to use to see if all I²C devices are detected as expected is this one:
i2cdetect -y 1
(sudo apt install i2c-tools if not found)
You should see “UU” on Pimidi’s address, as the address is in use by its kernel module, and the address of your LCD.
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Thanks for the feedback. I will experiment this (still waiting for my pimidi to arrive 
).
I have concerns relative to the fact that the I2C bus is shared with PiMidi and the LCD. I might experience bottleneck on the I2C bus and jitter wrt MIDI transmission… but let’s see.
It depends on your code - try making your screen updates in bursts, only when something changed, releasing the shared bus for other devices as much as possible. Give 400kHz baud rate a try, to see if the LCD manages updating at that rate, otherwise use 100kHz. I didn’t find the baud rate specification of the LCD anywhere.
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Hi, Thanks for the advice. I do not have the LCD spec neither. I will try.