configuration register 1
| DSIZE | Number of bits in at single SPI data frame |
| FTHVL | threshold level |
| UDRCFG | Behavior of slave transmitter at underrun condition |
| RXDMAEN | Rx DMA stream enable |
| TXDMAEN | Tx DMA stream enable |
| CRCSIZE | Length of CRC frame to be transacted and compared |
| CRCEN | Hardware CRC computation enable |
| MBR | Master baud rate |
| BPASS | BPASS |