The implementation uses the LPUARTx devices. Up to 8 UARTs can be used,
given that the pins are accessible. E.g. 8 on Teensy 4.1, 5 on
MIMXRT1020_EVK.
For Tennsy 4.0 and 4.1 the UART numbers are as printed on the pinout 1..N.
The MIMXRT10xx-EVK boards have only one UART named, which gets the number
1. All other UART are assigned to different Pins:
MIMXRT1010-EVK:
D0/D1 UART 1
D6/D7 UART 2
A0/D4 UART 3
MIMXRT1020-EVK:
D0/D1 UART 1
D6/D9 UART 2
D10/D12 UART 3
D14/D15 UART 4
A0/A1 UART 5
MIMXRT1050-EVK, MIMXRT1060-EVK, MIMXRT1064-EVK:
D0/D1 UART 1
D7/D6 UART 2
D8/D9 UART 3
A1/A0 UART 4
robert-hh