Datasheet

Tx FIFO Buffer
FIFO Status Prior to
Transfer
FIFO Status on
Completion of Transfer
Rx FIFO Buffer
Location n
Location 3
Location 2
Location 1
Location 0
Location n
Location 7
Location 6
Location 1
Location 0
Write DR
NULL
NULL SHIFT LOGIC
Address[7:0]
Address[15:8]
Opcode
Rx FIFO Empty
rxd
txd
Rx_Data(7)
Rx_Data(6)
Rx_Data(1)
Rx_Data(0)
NULL
Tx FIFO Empty
Read DR
Figure 127. FIFO
Status for EEPROM
Read Transfer Mode
4.11.10.2. Texas Instruments Synchronous Serial Protocol (SSP)
Data transfers begin by asserting the frame indicator line (ss_0_n/ss_in_n) for one serial clock period. Data to be
transmitted are driven onto the txd line one serial clock cycle later; similarly data from the slave are driven onto the rxd
line. Data are propagated on the rising edge of the serial clock (sclk_out/sclk_in) and captured on the falling edge. The
length of the data frame ranges from four to 32 bits.
Figure 128 shows the timing diagram for a single SSP serial transfer.
sclk_out/in
txd/rxd
ss_0_n/ss_in_n
ssi_oe_n
MSB LSB
Figure 128. SSP Serial
Format
Continuous data frames are transferred in the same way as single data frames. The frame indicator is asserted for one
clock period during the same cycle as the LSB from the current transfer, indicating that another data frame follows.
Figure 129 shows the timing for a continuous SSP transfer.
sclk_out/in
txd/rxd
ss_0_n/ss_in_n
ssi_oe_n
MSB LSB MSB
Figure 129. SSP Serial
Format Continuous
Transfer
4.11.10.3. National Semiconductor Microwire
Data transmission begins with the falling edge of the slave-select signal (ss_0_n). One-half serial clock (sclk_out) period
later, the first bit of the control is sent out on the txd line. The length of the control word can be in the range 1 to 16 bits
and is set by writing bit field CFS (bits 15:12) in CTRLR0. The remainder of the control word is transmitted (propagated on
the falling edge of sclk_out) by the DW_apb_ssi serial master. During this transmission, no data are present (high
impedance) on the serial master’s rxd line.
RP2040 Datasheet
4.11. SSI 605