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Last updated: 30 Jun 2020
The FRDM-K22F is an ultra-low-cost development platform for Kinetis K Series K2x (K22F) MCUs built on ARM® Cortex™-M4 processor. Features include easy access to MCU I/O, battery-ready, low-power operation, a …
Conflict between I2C pins on Arduino-compatible header and OpenSDA UART interface
Topic last updated 09 Aug 2016, by 
Mac Lobdell.
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Mac Lobdell.
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This would be good to have documented somewhere.
On FRDM-K22F, the same signals from the MCU used for D14 and D15 are also connected to the Open SDA (debug circuit) uart connection (UART1_TX, UART1_RX) for virtual com port.
So, if you are using a shield that requires I2C operation on D14, D15, then don't expect the usb virtual com port interface to continue to work and vice/versa. You can possibly jump back and forth between functions if you re-initialize the desired function each time.