Datasheet

Table Of Contents
4.11.8.3. Receive Only
When TMOD = 10b, the transmit data are invalid. When configured as a slave, the transmit FIFO is never popped in Receive
Only mode. The txd output remains at a constant logic level during the transmission. The data transfer occurs as normal
according to the selected frame format (serial protocol). The receive data from the target device is moved from the
receive shift register into the receive FIFO at the end of each data frame. You should mask interrupts originating from the
transmit logic when this mode is entered.
4.11.8.4. EEPROM Read
NOTE
This transfer mode is only valid for master configurations.
When TMOD = 11b, the transmit data is used to transmit an opcode and/or an address to the EEPROM device. Typically
this takes three data frames (8-bit opcode followed by 8-bit upper address and 8-bit lower address). During the
transmission of the opcode and address, no data is captured by the receive logic (as long as the DW_apb_ssi master is
transmitting data on its txd line, data on the rxd line is ignored). The DW_apb_ssi master continues to transmit data until
the transmit FIFO is empty. Therefore, you should ONLY have enough data frames in the transmit FIFO to supply the
opcode and address to the EEPROM. If more data frames are in the transmit FIFO than are needed, then read data is lost.
When the transmit FIFO becomes empty (all control information has been sent), data on the receive line (rxd) is valid and
is stored in the receive FIFO; the txd output is held at a constant logic level. The serial transfer continues until the number
of data frames received by the DW_apb_ssi master matches the value of the NDF field in the CTRLR1 register + 1.
NOTE
EEPROM read mode is not supported when the DW_apb_ssi is configured to be in the SSP mode.
4.11.9. Operation Modes
The DW_apb_ssi can be configured in the fundamental modes of operation discussed in this section.
4.11.9.1. Serial Master Mode
This mode enables serial communication with serial-slave peripheral devices. When configured as a serial-master device,
the DW_apb_ssi initiates and controls all serial transfers. Figure 116 shows an example of the DW_apb_ssi configured as
a serial master with all other devices on the serial bus configured as serial slaves.
RP2040 Datasheet
4.11. SSI 596