9.5.3.11 RREG

Use the RREG command to read the device register data. Read the register data one register at a time, or read a block of register data. The starting register address can be any register in the register map. The RREG command consists of two bytes. The first byte specifies the starting register address: 001r rrrr, where r rrrr is the starting register address. The second command byte is the number of registers to read (minus 1): 000n nnnn, where n nnnn is the number of registers to read minus 1.

After the read command is sent, the ADC responds with one or more register data bytes, most significant bit (MSB) first. If the byte count exceeds the last register address, the ADC begins to output zero data. During the register read operation, any conversion data that becomes available is not loaded to the output shift register to avoid data contention. However, the conversion data can be retrieved later by the RDATA command. After the register read command has started, further commands are blocked until one of the following conditions are met:

• The read operation is completed
• The read operation is terminated by taking CS high
• The read operation is terminated by a serial interface timeout
• The ADC is reset by toggling the RESET pin

Figure 74 shows a two-register read operation example. As shown, the commands required to read data from two registers starting at register REF (address = 05h) are: command byte 1 = 25h and command byte 2 = 01h. Keep DIN low after the two command bytes are sent.

1. CS can be set high or kept low between commands. If kept low, the command must be completed.

Figure 74. Read Register Sequence