Datasheet

Table Of Contents
NOTE
For the remaining three characters, the PrimeCell SSP does not assert the burst request.
Each request signal remains asserted until the relevant DMA clear signal is asserted. After the request clear signal is
deasserted, a request signal can become active again, depending on the conditions that previous sections describe. All
request signals are deasserted if the PrimeCell SSP is disabled, or the DMA enable signal is cleared.
Table 523 shows the trigger points for DMABREQ, for both the transmit and receive FIFOs.
Table 523. DMA
trigger points for the
transmit and receive
FIFOs
Burst length
Watermark level Transmit, number of empty locations Receive, number of filled locations
1/2 4 4
Figure 100 shows the timing diagram for both a single transfer request, and a burst transfer request, with the appropriate
DMA clear signal. The signals are all synchronous to PCLK.
PCLK
DMABREQ
DMASREQ
DMACLR
Figure 100. DMA
transfer waveforms
4.5.4. List of Registers
Table 524. List of SPI
registers
Offset Name Info
0x000 SSPCR0 Control register 0, SSPCR0 on page 3-4
0x004 SSPCR1 Control register 1, SSPCR1 on page 3-5
0x008 SSPDR Data register, SSPDR on page 3-6
0x00c SSPSR Status register, SSPSR on page 3-7
0x010 SSPCPSR Clock prescale register, SSPCPSR on page 3-8
0x014 SSPIMSC Interrupt mask set or clear register, SSPIMSC on page 3-9
0x018 SSPRIS Raw interrupt status register, SSPRIS on page 3-10
0x01c SSPMIS Masked interrupt status register, SSPMIS on page 3-11
0x020 SSPICR Interrupt clear register, SSPICR on page 3-11
0x024 SSPDMACR DMA control register, SSPDMACR on page 3-12
0xfe0 SSPPERIPHID0 Peripheral identification registers, SSPPeriphID0-3 on page 3-13
0xfe4 SSPPERIPHID1 Peripheral identification registers, SSPPeriphID0-3 on page 3-13
0xfe8 SSPPERIPHID2 Peripheral identification registers, SSPPeriphID0-3 on page 3-13
0xfec SSPPERIPHID3 Peripheral identification registers, SSPPeriphID0-3 on page 3-13
0xff0 SSPPCELLID0 PrimeCell identification registers, SSPPCellID0-3 on page 3-16
0xff4 SSPPCELLID1 PrimeCell identification registers, SSPPCellID0-3 on page 3-16
0xff8 SSPPCELLID2 PrimeCell identification registers, SSPPCellID0-3 on page 3-16
0xffc SSPPCELLID3 PrimeCell identification registers, SSPPCellID0-3 on page 3-16
SSPCR0 Register
RP2040 Datasheet
4.5. SPI 540