PCF8574T / PCF8574AT running at 800 MHz

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sixeight

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PCF8574T / PCF8574AT i2c serial board running at 800 MHz

I have developed a Midi foot controller with 13 displays running on the i2c bus. I have posted this over here: https://forum.pjrc.com/threads/34072-V-Controller-version-2

The displays are controlled by the LiquidCrystal i2c library

I found writing data to so many displays took a lot of time and really slowed down the loop. Changing the Wire library to the i2c_t3 library doubled the speed. But I was able to boost performance even more by changing the i2c clock speed to 800 kHz. Officially the PCF8574 chips only support 100 kHz, but so far they run great at 800 kHz.

With this amount of displays it really makes a big difference. I thought the MIDI was slow, but it actually was the i2c bus that was the bottleneck.

The third version of the VController uses mcp23017 chips for the displays, which run even faster.
 
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