RREG is used to read the device registers. The binary format of the command word is 101a aaaa aaan nnnn, where a aaaa aaa is the binary address of the register to begin reading from and n nnnn is the unsigned binary number of consecutive registers to read minus one. The device outputs the requested register data sequentially in order of addresses in the following frame instead of the conversion data of ADC1A, ADC1B, ADC3A, and ADC3B. If more than four registers are read, the frame extends beyond the regular six words.

Send the NULL command in the frame following the RREG command frame to shift out the register data. No other command is accepted in the frame following the RREG command frame.

The 16-bit register data are MSB aligned within the individual words. As illustrated in Figure 9-30, the device outputs the respective 8-bit register address following the register data within each word for traceability. When reading from an invalid register address, the device responds with 0000h for the register data and 00h for the register address.

The command response in the frame following the RREG command frame indicates if the RREG command executed successfully or if an error occurred that prevented the RREG command from executing. A NULL command is executed if the RREG command did not execute.

Figure 9-37 shows a RREG command frame where no faults occurred during the communication.

Figure 9-37 RREG Command Frame