SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The xSPI protocol defines 1S-1S-1S mode for general backwards compatibility, and 8D-8D-8D for maximum throughput (where bit-width (1 or 8) and data rate (S or D for *S*ingle Data rate or *D*ouble Data rate).
For 1S-1S-1S mode of operation (Bit-width =1, Single Data Rate): The Command and Address issued are 8 bits and 24 bits, respectively. The Read Command issued is 0x0b followed by zero for address and 8 dummy cycles. The frequency of operation supported is 50 MHz.
For 8D-8D-8D mode of operation (Bit-width =8, Double Data Rate): The Command and Address issued are 8 bits and 32 bits, respectively. The Read Command issued is 0x0b or 0xee, followed by zero for address, 16 or 20 dummy cycles. The frequency of operation supported is 25 MHz. Additionally, the flash is expected to be configured in 8D mode out of POR through nonvolatile configuration register.
For SFDP mode, ROM starts operation in 1S-1S-1S mode, reads SFDP header from flash memory to get 8D-8D-8D switching sequence, Read Command, CMD Extension, and Byte Order. SFDP parsing of ROM is described below; on successful parsing, ROM issues an 8D-8D-8D command switching sequence and then reads the boot image in 8D-8D-8D mode with the read command specified in the SFDP header.
The following boot mode pin configuration and corresponding pin usage and mux configuration are shown below. This is the xSPI boot mode.
9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Rsvd (not for boot use) | Rsvd | MCU Only | Primary Boot Mode A | PLL Config | |||||
X | X | X | X | 1 | 1 | 0 | X | X | X |
7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
Backup Boot Mode Config | Primary Boot Mode Config | Backup Boot Mode | Primary Boot B | ||||
X | 0/1 | 0/1 | 0/1 | X | X | X | 1 |
Table 4-25 shows configuration pins assignment to functions when boot mode is the xSPI on OSPI port mode.
BOOTMODE Pins | Field | Value | Description | MCU Only=1 Value |
---|---|---|---|---|
6 | SFDP | 0 | SFDP (Serial Flash Discovery Parameter) Disabled | 0 |
1 | SFDP Enabled | |||
5 | Pin Cmd | 0 | 0x0B Read Command | 0 |
1 | 0xEE Read Command | |||
4 | Mode | 0 | SPI-STR (1S-1S-1S) at 50 MHz | 0 |
1 | OCTAL-DTR (8D-8D-8D) at 25 MHz |
Table 4-26 summarizes the OSPI pin configuration done by ROM code for xSPI boot device on port 0.
Device Pin | Module Signal | Pull Enable | Pull Direction | Driver Index | Rx En/Dis | Tx En/Dis | Pinmux Sel |
---|---|---|---|---|---|---|---|
MCU_OSPI0_CLK0 | MCU_OSPI0_CLK | Disable | Up | 0 | Disable | Enable | 0 |
MCU_OSPI0_LBCLKO | MCU_OSPI0_LBCLKO | Disable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_DQS | MCU_OSPI0_DQS | Disable | Up | 0 | Enable | Disable | 0 |
MCU_OSPI0_D0 | MCU_OSPI0_D0 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D1 | MCU_OSPI0_D1 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D2 | MCU_OSPI0_D2 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D3 | MCU_OSPI0_D3 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D4 | MCU_OSPI0_D4 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D5 | MCU_OSPI0_D5 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D6 | MCU_OSPI0_D6 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_D7 | MCU_OSPI0_D7 | Enable | Up | 0 | Enable | Enable | 0 |
MCU_OSPI0_CSn0 | MCU_OSPI0_CSn0 | Enable | Up | 0 | Disable | Enable | 0 |
MCU_OSPI0_CSn1 | MCU_OSPI0_CSn1 | Enable | Up | 0 | Disable | Enable | 0 |