JAJSOX0A March 2024 – June 2024 ADS127L18
ADVANCE INFORMATION
The read register command reads register data. The command follows an off-frame protocol where the read command is sent in one frame and the ADC responds with register data in the next frame. The first byte of the read command is 00h plus a 7-bit register address. The second byte is an arbitrary value. The response to a register address outside the valid range is 00h. When the SPI out-of-range address feature is enabled, the ADDR_ERR flag is set in the STATUS byte. The register data format is most-significant-bit first. Full duplex operation is supported by shifting in the next command during the data output frame.
Figure 7-44 shows an example of reading register data with the STATUS and CRC bytes disabled. Frame 1 is the command frame and frame 2 is the register data response frame. The frames are delimited by taking CS high. In this example, the length of the response frame is two bytes long because the STATUS and CRC bytes are disabled. Terminate the response frame after reading the register data by taking CS high.
Figure 8-6 shows an example of reading register data with the SPI STATUS and CRC bytes enabled. In this example, the length of the frames are three bytes long because the STATUS and CRC bytes are enabled. The value of the second command byte is arbitrary, but is used with the first byte for the CRC In byte calculation. The register data and the STATUS bytes are used for the CRC Out calculation.