45.7.1 TWIHS Control Register


Bit	31	30	29	28	27	26	25	24
			FIFODIS	FIFOEN		LOCKCLR		THRCLR
Access			W	W		W		W
Reset			–	–		–		–


Bit	23	22	21	20	19	18	17	16
							ACMDIS	ACMEN
Access							W	W
Reset							–	–


Bit	15	14	13	12	11	10	9	8
	CLEAR	PECRQ	PECDIS	PECEN	SMBDIS	SMBEN	HSDIS	HSEN
Access	W	W	W	W	W	W	W	W
Reset	–	–	–	–	–	–	–	–


Bit	7	6	5	4	3	2	1	0
	SWRST	QUICK	SVDIS	SVEN	MSDIS	MSEN	STOP	START
Access	W	W	W	W	W	W	W	W
Reset	–	–	–	–	–	–	–	–

Bit 29 – FIFODIS FIFO Disable

Value	Description
0	No effect.
1	Disables the Transmit and Receive FIFOs.

Bit 28 – FIFOEN FIFO Enable

Value	Description
0	No effect.
1	Enables the Transmit and Receive FIFOs.

Bit 26 – LOCKCLR Lock Clear

The LOCKCLR bit is used to clear any lock scenario generated due to Error conditions of NACK, Host Code ACK Error, and SMBUS Timeout.

Any of the above error scenarios basically lock the TWIHS state machine and prevent its movement for any new transfer, no further operation occurs until the LOCK is cleared.

Value	Description
0	No effect.
1	Clears the TWIHS FSM lock.

Bit 24 – THRCLR Transmit Holding Register Clear

Value	Description
0	No effect.
1	Clears the Transmit Holding Register and sets TXRDY, TXCOMP flags.

Bit 17 – ACMDIS Alternative Command Mode Disable

Value	Description
0	No effect.
1	Alternative Command mode disabled.

Bit 16 – ACMEN Alternative Command Mode Enable

Value	Description
0	No effect.
1	Alternative Command mode enabled.

Bit 15 – CLEAR Bus CLEAR Command

Value	Description
0	No effect.
1	If Host mode is enabled, sends a bus clear command.

Bit 14 – PECRQ PEC Request

Value	Description
0	No effect.
1	A PEC check or transmission is requested.

Bit 13 – PECDIS Packet Error Checking Disable

Value	Description
0	No effect.
1	SMBus PEC (CRC) generation and check disabled.

Bit 12 – PECEN Packet Error Checking Enable

Value	Description
0	No effect.
1	SMBus PEC (CRC) generation and check enabled.

Bit 11 – SMBDIS SMBus Mode Disabled

Value	Description
0	No effect.
1	SMBus mode disabled.

Bit 10 – SMBEN SMBus Mode Enabled

Value	Description
0	No effect.
1	If SMBDIS = 0, SMBus mode enabled.

Bit 9 – HSDIS TWIHS High-Speed Mode Disabled

Value	Description
0	No effect.
1	High-speed mode disabled.

Bit 8 – HSEN TWIHS High-Speed Mode Enabled

Value	Description
0	No effect.
1	High-speed mode enabled.

Bit 7 – SWRST Software Reset

Value	Description
0	No effect.
1	Equivalent to a system reset.

Bit 6 – QUICK SMBus Quick Command

Value	Description
0	No effect.
1	If Host mode is enabled, a SMBus Quick Command is sent.

Bit 5 – SVDIS TWIHS Client Mode Disabled

Value	Description
0	No effect.
1	The Client mode is disabled. The shifter and holding characters (if it contains data) are transmitted in case of read operation. In write operation, the character being transferred must be completely received before disabling.

Bit 4 – SVEN TWIHS Client Mode Enabled

Switching from Host to Client mode is only permitted when TXCOMP = 1.

Value	Description
0	No effect.
1	Enables the Client mode (SVDIS must be written to 0).

Bit 3 – MSDIS TWIHS Host Mode Disabled

Value	Description
0	No effect.
1	The Host mode is disabled, all pending data is transmitted. The shifter and holding characters (if it contains data) are transmitted in case of write operation. In read operation, the character being transferred must be completely received before disabling.

Bit 2 – MSEN TWIHS Host Mode Enabled

Switching from Client to Host mode is only permitted when TXCOMP = 1.

Value	Description
0	No effect.
1	Enables the Host mode (MSDIS must be written to 0).

Bit 1 – STOP Send a STOP Condition

Value

Description

0

No effect.

1

STOP condition is sent just after completing the current byte transmission in Host Read mode.

In single data byte host read, both START and STOP must be set.
In multiple data bytes host read, the STOP must be set after the last data received but one.
In Host Read mode, if a NACK bit is received, the STOP is automatically performed.
In host data write operation, a STOP condition will be sent after the transmission of the current data is finished.

Bit 0 – START Send a START Condition

This action is necessary when the TWIHS peripheral needs to read data from a client. When configured in Host mode with a write operation, a frame is sent as soon as the user writes a character in the Transmit Holding Register (TWIHS_THR).