PSoC 4000 Family: PSoC 4 Architecture TRM, Document No. 001-89309 Rev. *D 87
Inter-Integrated Circuit (I2C)
15.2.4 I2C Registers
The I
2
C interface is controlled by reading and writing a set of configuration, control, and status registers, as listed in
Table 15-4.
Note Detailed descriptions of the I
2
C register bits are available in the PSoC 4000 Family: PSoC 4 Registers TRM.
Table 15-4. I2C Registers
Register Function
SCB_CTRL
Enables the I2C block and selects the type of serial interface (I2C). Also used to select internally and exter-
nally clocked operation and EZ and non-EZ modes of operation.
SCB_I2C_CTRL Selects the mode (master, slave) and sends an ACK or NACK signal based on receiver FIFO status.
SCB_I2C_STATUS
Indicates bus busy status detection, read/write transfer status of the slave/master, and stores the EZ slave
address.
SCB_I2C_M_CMD Enables the master to generate START, STOP, and ACK/NACK signals.
SCB_I2C_S_CMD Enables the slave to generate ACK/NACK signals.
SCB_STATUS
Indicates whether the externally clocked logic is using the EZ memory. This bit can be used by software to
determine whether it is safe to issue a software access to the EZ memory.
SCB_I2C_CFG Configures filters, which remove glitches from the SDA and SCL lines.
SCB_TX_CTRL Specifies the data frame width; also used to specify whether MSB or LSB is the first bit in transmission.
SCB_TX_FIFO_CTRL
Specifies the trigger level, clearing of the transmitter FIFO and shift registers, and FREEZE operation of the
transmitter FIFO.
SCB_TX_FIFO_STATUS
Indicates the number of bytes stored in the transmitter FIFO, the location from which a data frame is read by
the hardware (read pointer), the location from which a new data frame is written (write pointer), and decides
if the transmitter FIFO holds the valid data.
SCB_TX_FIFO_WR Holds the data frame written into the transmitter FIFO. Behavior is similar to that of a PUSH operation.
SCB_RX_CTRL
Performs the same function as that of the SCB_TX_CTRL register, but for the receiver. Also decides
whether a median filter is to be used on the input interface lines.
SCB_RX_FIFO_CTRL Performs the same function as that of the SCB_TX_FIFO_CTRL register, but for the receiver.
SCB_RX_FIFO_STATUS Performs the same function as that of the SCB_TX_FIFO_STATUS register, but for the receiver.
SCB_RX_FIFO_RD
Holds the data read from the receiver FIFO. Reading a data frame removes the data frame from the FIFO;
behavior is similar to that of a POP operation. This register has a side effect when read by software: a data
frame is removed from the FIFO.
SCB_RX_FIFO_RD_SILENT
Holds the data read from the receiver FIFO. Reading a data frame does not remove the data frame from the
FIFO; behavior is similar to that of a PEEK operation.
SCB_RX_MATCH Stores slave device address and is also used as slave device address MASK.
SCB_EZ_DATA Holds the data in an EZ memory location.
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