37.5.1 I2CxCON0

I2C Control Register 0
Note:
  1. SDA and SCL pins must be configured as open-drain I/Os and use either internal or external pull-up resistors.
  2. SDA and SCL signals must configure both the input and output PPS registers for each signal.
  3. CSTR can be set by multiple hardware sources; all sources must be addressed by user software before the SCL line can be released.
  4. SMA is set on the same SCL edge as CSTR for a matching received address.
  5. In this mode, ADRIE must be set, allowing an interrupt to clear the BCLIF condition and the ACK of a matching address.
  6. In 10-bit Client mode (when ABD = 1), CSTR will be set when the high address has not been read from I2CxRXB before the low address is shifted in.
Name: I2CxCON0
Address: 0x292, 0x2A9

Bit 76543210 
 ENRSENSCSTRMDRMODE[2:0] 
Access R/WR/WR/W/HS/HCR/C/HS/HCRR/WR/WR/W 
Reset 00000000 

Bit 7 – EN  I2C Module Enable(1,2)

ValueDescription
1 The I2C module is enabled
0 The I2C module is disabled

Bit 6 – RSEN  Restart Enable (used only when MODE = 1xx)

ValueDescription
1 Hardware sets MDR on 9th falling SCL edge (when I2CxCNT = 0 or ACKSTAT = 1)
0 Hardware issues Stop condition on 9th falling SCL edge (when I2CxCNT = 0 or ACKSTAT = 1)

Bit 5 – S  Host Start (used only when MODE = 1xx)

ValueNameDescription
1 MMA = 0: Set by write to I2CxTXB or S bit, hardware issues Start condition
0 MMA = 0: Cleared by hardware after sending Start condition
1 MMA = 1 and MDR = 1: Set by write to I2CxTXB or S bit, communication resumes with a Restart condition
0 MMA = 1 and MDR = 1: Cleared by hardware after sending Restart condition

Bit 4 – CSTR  Client Clock Stretching(3)

ValueNameDescription
1 Clock is held low (clock stretching)
0 Enable clocking, SCL control is released
SMA = 1 and RXBF = 1(6): Set by hardware on 7th falling SCL edge.

User must read I2CxRXB and clear CSTR to release SCL.
SMA = 1 and TXBE = 1 and I2CxCNT != 0: Set by hardware on 8th falling SCL edge.

User must write to I2CxTXB and clear CSTR to release SCL.
when ADRIE = 1(4): Set by hardware on 8th falling edge of matching received address.

User must clear CSTR to release SCL.
SMA = 1 and WRIE = 1: Set by hardware on 8th falling SCL edge of received data byte.

User must clear CSTR to release SCL.
SMA = 1 and ACKTIE = 1: Set by hardware on 9th falling SCL edge.

User must clear CSTR to release SCL.

Bit 3 – MDR  Host Data Request (Host pause)

ValueNameDescription
1 Host state machine pauses until data is read/written (SCL is held low)
0 Host clocking of data is enabled
MMA = 1 and RXBF = 1 (pause for RX): Set by hardware on 7th falling SCL edge.

User must read I2CxRXB to release SCL.
MMA = 1 and TXBE = 1 and I2CxCNT != 0 (pause for TX): Set by hardware on the 8th falling SCL edge.

User must write to I2CxTXB to release SCL.
RSEN = 1 and MMA = 1 and (I2CxCNT = 0 or ACKSTAT = 1) (pause for Restart): Set by hardware on 9th falling SCL edge.

User must set S bit or write to I2CxTXB to release SCL and issue a Restart condition.

Bits 2:0 – MODE[2:0]  I2C Mode Select

ValueDescription
111 I2C Multi-Host mode (SMBus 2.0 Host)(5)
110 I2C Multi-Host mode (SMBus 2.0 Host)(5)
101 I2C Host mode, 10-bit address
100 I2C Host mode, 7-bit address
011 I2C Client mode, one 10-bit address with masking
010 I2C Client mode, two 10-bit addresses
001 I2C Client mode, two 7-bit addresses with masking
000 I2C Client mode, four 7-bit addresses
SDA and SCL pins must be configured as open-drain I/Os and use either internal or external pull-up resistors. SDA and SCL signals must configure both the input and output PPS registers for each signal. CSTR can be set by multiple hardware sources; all sources must be addressed by user software before the SCL line can be released. SMAClient Mode Active Status is set on the same SCL edge as CSTR for a matching received address. In this mode, ADRIE Address Interrupt and Hold Enable(1,4) must be set, allowing an interrupt to clear the BCLIF Bus Collision Detect Interrupt Flag(1) condition and the ACK of a matching address. In 10-bit Client mode (when ABDAddress Buffer Disable = 1), CSTR will be set when the high address has not been read from I2CxRXBI2CxRXB before the low address is shifted in.