The receive register is a buffer that holds data received from the master over the MOSI line. Table 2 shows the addresses of each register. The wr_addr bit identifies which slave register the MOSI line writes to during the data transfer, and the rd_addr bit identifies which register the MISO line transmits back to the master. The SPI slave component contains three registers: receive, transmit, and status.
The master must send the command MSB first. Table 1 defines the 8-bit command sent over MOSI by the master. Spi_transaction_diagram 1145×241 34.9 KB 8-bit Command The timing diagram in Figure 2 depicts the four SPI modes. If CPHA is one, data is written on the first SCLK edge and read on the second SCLK edge. If CPHA is zero, then the first data bit is written on the SS falling edge and read on the first SCLK edge. If CPOL is one, SCLK is normally high, and the first clock edge is a falling edge. If CPOL is zero, then SCLK is normally low, and the first clock edge is a rising edge. Master and slave must use the same mode to communicate articulately. SPI has four modes of operation, based on two parameters: clock polarity (CPOL) and clock phase (CPHA). Each slave ignores the shared lines when its SS line is not pulled low. In the most common configuration, each slave has an independent SS line but shares the SCLK, MISO, and MOSI lines with the other slaves. The master transmits data via the Master Out, Slave In (MOSI) line and receives data via the Master In, Slave Out (MISO) line.Ī master can communicates with multiple slaves via a variety of techniques.
#QUAD SPI PROGRAMMER SERIAL#
A Serial Clock (SCLK) line, driven by the master, provides a synchronous clock source. The master initiates the transaction by pulling the Slave Select (SS) wire low. Figure 1 illustrates a typical example of the SPI slave integrated into a system.Īn SPI communication scheme is a full-duplex data link, using four wires. Resource requirements depend on the implementation (i.e. The component was designed using Quartus II, version 11.1. This details an SPI slave component for use in CPLDs and FPGAs, written in VHDL. Status register bits available to user logic.Status register bits available to the master via SPI transaction and/or via individual pin interrupts.Status register with Transmit Ready, Receive Ready, and Receive Overrun Error bits.
#QUAD SPI PROGRAMMER SOFTWARE#
In quad mode, the software automatically distributes the data bytes among the IO lines using the same bit pattern depicted in Figure 8 above.Modified architecture slightly to make it synthesizable with more tools Note that we’re changing from 4-wire mode to quad mode in the middle of the transaction. Wt AA AA AA 00 // Write 3-byte address and 8 read mode bits Compare this to the 16 clock cycles required for our simple read transaction and it’s easy to see why quad mode is gaining popularity for high speed flash memory applications! To create this sequence in the SPI Exerciser command language, we would use the example code: 4m // Start in 4-wire mode Quad mode fast read sequence for Spansion S25FL016K or equivalentĪfter the address cycle and dummy bytes have been sent by the host, the component begins sending data bytes each clock cycle consists of a data nibble spread across the 4 IO lines, for a total of two clock cycles per byte of data. JTAG Boundary-Scan & JET Technology Benefits FAQįigure 8.On-site JTAG Boundary-Scan Training Classes.Test Genie: Turnkey Boundary-Scan Solution.Development Station (Boundary-Scan & ISP Only).Controllers for High-Volume Production Systems.