ctrlr0

This register controls the serial data transfer. It is impossible to write to this register when the SPI Master is enabled. The SPI Master is enabled and disabled by writing to the SPIENR register.

Module Instance	Base Address	Register Address
`spim0`	`0xFFF00000`	`0xFFF00000`
`spim1`	`0xFFF01000`	`0xFFF01000`

Offset: 0x0

Access: RW

Important: To prevent indeterminate system behavior, reserved areas of memory must not be accessed by software or hardware. Any area of the memory map that is not explicitly defined as a register space or accessible memory is considered reserved.

Bit Fields
31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16
`Reserved`
15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
`cfs` `RW 0x0`				`srl` `RW 0x0`	`Reserved`	`tmod` `RW 0x0`		`scpol` `RW 0x0`	`scph` `RW 0x0`	`frf` `RW 0x0`		`dfs` `RW 0x7`

ctrlr0 Fields

Bit

Name

Description

Access

Reset

15:12

cfs

Selects the length of the control word for the Microwire frame format. The length (in bits) is the value of this field plus 1.

Value	Description
0x0	1-bit control word
0x1	2-bit control word
0x2	3-bit control word
0x3	4-bit control word
0x4	5-bit control word
0x5	6-bit control word
0x6	7-bit control word
0x7	8-bit control word
0x8	9-bit control word
0x9	10-bit control word
0xA	11-bit control word
0xB	12-bit control word
0xC	13-bit control word
0xD	14-bit control word
0xE	15-bit control word
0xF	16-bit control word

RW

0x0

srl

Used for testing purposes only. When internally active, connects the transmit shift register output to the receive shift register input.

Value	Description
0x0	Normal Mode Operation
0x1	Test Mode Operation

RW

0x0

9:8

tmod

Selects the mode of transfer for serial communication. This field does not affect the transfer duplicity. Only indicates whether the receive or transmit data are valid. In transmit-only mode, data received from the external device is not valid and is not stored in the receive FIFO memory. It is overwritten on the next transfer. In receive-only mode, transmitted data are not valid. After the first write to the transmit FIFO, the same word is retransmitted for the duration of the transfer. In transmit-and-receive mode, both transmit and receive data are valid. The transfer continues until the transmit FIFO is empty. Data received from the external device are stored into the receive FIFO memory, where it can be accessed by the host processor.

Value	Description
0x0	Transmit & and Receive
0x1	Transmit Only
0x2	Receive Only
0x3	EEPROM Read

RW

0x0

scpol

Valid when the frame format (FRF) is set to Motorola SPI. Used to select the polarity of the inactive serial clock, which is held inactive when the SPI Master is not actively transferring data on the serial bus.

Value	Description
0x0	Inactive state of serial clock is low
0x1	Inactive state of serial clock is high

RW

0x0

scph

Valid when the frame format (FRF) is set to Motorola SPI. The serial clock phase selects the relationship of the serial clock with the slave select signal. When SCPH = 0, data are captured on the first edge of the serial clock. When SCPH = 1, the serial clock starts toggling one cycle after the slave select line is activated, and data are captured on the second edge of the serial clock.

Value	Description
0x0	Serial clock toggles in middle of first data bit
0x1	Serial clock toggles at start of first data bit

RW

0x0

5:4

frf

Selects which serial protocol transfers the data.

Value	Description
0x0	Motorola SPI
0x1	Texas Instruments SSP
0x2	National Semi Microwire

RW

0x0

3:0

dfs

Selects the data frame length. When the data frame size is programmed to be less than 16 bits, the receive data are automatically right-justified by the receive logic, with the upper bits of the receive FIFO zero-padded. You must right-justify transmit data before writing into the transmit FIFO. The transmit logic ignores the upper unused bits when transmitting the data.

Value	Description
0x3	4-bit serial data transfer
0x4	5-bit serial data transfer
0x5	6-bit serial data transfer
0x6	7-bit serial data transfer
0x7	8-bit serial data transfer
0x8	9-bit serial data transfer
0x9	10-bit serial data transfer
0xA	11-but serial data
0xB	12-bit serial data
0xC	13-bit serial data
0xD	14-bit serial data
0xE	15-bit serial data
0xF	16-bit serial data

RW

0x7