This class supports SPI bus controller mode, with blocking transfers.
SPI device numbers start at 0, to comply with the pinout of the Teensy
boards. With the configured clock frequency the fastest baud rate is
33MHz. For messages longer 16 bytes DMA is used. The class uses the
existing framework with extmod/machine_spi.c.
Extended driver options:
- drive=n with n being between 1 and 6 or PIN.POWER_1 to PIN.POWER_6.
Since the pins used by the SPI are fixed, no Pin settings can be made.
Thus the drive option is added allowing to control ringing and crosstalk
on the connection.
- gap_ns=nnnnn is the time between sent data items in a frame given in ns.
Default is 2 clock cycles.
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
