The SPI Read operation for TXE8124 is used to retrieve data from a specific register in single read mode as shown in Figure 7-9 or sequential registers in burst mode as shown in Figure 7-10.

Figure 7-9 SPI Single Read

Figure 7-10 SPI Burst Read

SPI Read Operation Steps:

1. Drive CS low. This enables the internal shift register.
2. Shift 24 bits of data into the device in a MSB first fashion. Data must be stable during the rising edge of SCLK
3. The MSB bit must be a '1' indicating it is a read only transfer.
4. The third data byte is NOP (no operation) which is dummy data byte.
5. On the SDO pin the device sends the first 2 bits as 2’b11 (indicating it to be a status segment), followed by 6 bits that are the Bit 5 to 0 of Fault status register. The next 8 bits are all 0s followed by 8-bit current data in the register selected by register pointer.
6. After the last bit of data is transferred, drive SCLK low if there is no more data to be transferred.
7. De-assert CS (drive it high) to end the read cycle.