The LDC3114 features an I²C Interface that can be used to program the internal registers and read channel data. Before reading the OUT (Address 0x01) or channel DATAn (n = 0, 1, 2 or 3, Addresses 0x02 through 0x09) registers for button press data or raw channel data, RAW_DATAn_x (n = 0, 1, 2, or 3, for each channel, x= 1, 2, or 3 splitting 24-bit data over 3 8-bit register fields), the user should always read Register STATUS (Address 0x00) first to lock the data. The LDC3114 supports burst mode with auto-incrementing register addresses. The LDC3114 has a fixed I²C address of 0x2A.

For the write sequence, there is a special handshake process that has to take place to ensure data integrity. The sequence of register writes is:

• Set CONFIG_MODE (Register RESET, Address 0x0A) bit = 1 to start the register write session.
• Poll for RDY_TO_WRITE (Register STATUS, Address 0x00) bit = 1.
• Perform I²C write to configure registers.
• Set CONFIG_MODE (Register RESET, Address 0x0A) bit = 0 to terminate the register write session.

After CONFIG_MODE is de-asserted, the new scan cycle will start in less than 1 ms. Figure 7-3 shows the waveform of the above process.

Figure 7-3 Timing Diagram Representing the States of the CONFIG_MODE and RDY_TO_WRITE Bits for an I²C Write Handshake