MAX32665-MAX32668 User Guide
Maxim Integrated Page 317 of 457
Three-Wire SPI Enable
Set this field to 1 to enable three-wire SPI communication. Set this field to 0 for
four-wire full-duplex SPI communication.
0: Four-wire full-duplex mode enabled.
1: Three-wire mode enabled
Note: This field is ignored for Dual SPI, QSPIn_CTRL2.data_width =1, and Quad
SPI, QSPIn_CTRL2.data_width =2, this field is ignored.
Reserved for Future Use
Do not modify this field.
SPI Data Width
This field controls the number of data lines used for SPI communications.
Three-wire SPI, data_width = 0
Set this field to 0, indicating QSPIn_MOSI (SISO) is used for half duplex
communication.
Four-wire full-duplex SPI operation, data_width = 0
Set this field to 0, indicating QSPIn_MOSI and QSPIn_MISO are used for the SPI
data output and input respectively.
Dual SPI, data_width = 1, uses QSPIn_SDIO0 and QSPIn_SDIO1 for half-duplex
communication.
Quad SPI, data_width = 2, uses QSPIn_SDIO0, QSPIn_SDIO1, QSPIn_SDIO2 and
QSPIn_SDIO3 for half-duplex communication.
0: 1-bit per SCK cycle (Three-wire half duplex SPI and Four-wire full duplex SPI)
1: 2-bits per SCK cycle (Dual SPI)
2: 4-bits per SCK cycle (Quad SPI)
3: Reserved
Note: When this field is set to 0, use the field QSPIn_CTRL2.three_wire to select
either Three-Wire SPI or Four-Wire SPI operation.
Number of Bits per Character
Set this field to the number of bits per character for the SPI transaction. Setting
this field to 0 indicates a character size of 16.
0: 16-bits per character
1: 1-bit per character
2: 2-bits per character
…
14: 14-bits per character
15: 15-bits per character
Note: 1-bit and 9-bit character lengths are not supported in Slave Mode,
QSPIn_CTRL0.mm_en = 0.
Note: For Dual and Quad mode SPI, the character size should be divisible by the
number of bits per SCK cycle.
Reserved for Future Use
Do not modify this field.
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