USB5537B datasheet(17/79 Pages) MICROCHIP

17 / 79 page

 2012 - 2015 Microchip Technology Inc.

DS00001682C-page 17

USB5537B

4.1.4.3

COMMAND ONLY PROGRAM EXAMPLE

To perform a single byte command such as the following:

- - WRDI

-- WREN

- - EWSR

- - CHIP_ERASE

- - EBSY

- - DBSY

The device writes the opcode into the first byte of the SPI_CMD_BUF and the SPI_CMD_LEN is set to one. The device

first drops SPI_CE, then 8 bits of the command are clocked out on the SPI_DO pin. The SPI_DI is not used in this exam-

ple.

4.1.4.4

JEDEC-ID READ EXAMPLE

To perform a JEDEC-ID command, the device writes 0x9F into the first byte of the SPI_CMD_BUF and the length of the

transfer is 4 bytes. The device first drops SPI_CE_N, then 8 bits of the command are clocked out, followed by the 24

bits of dummy bytes (due to the length being set to 4) on the SPI_DO pin. When the transfer is complete, the SPI_CE_N

goes high. After the first byte, the data on SPI_DI is clocked into the SPI_RSP_BUF. At the end of the command, there

are three valid bytes in the SPI_RSP_BUF. In this example, 0xBF, 0x25, 0x8E.

FIGURE 4-8:

SPI COMMAND ONLY SEQUENCE

SPI_CEN

SPI_CLK

12 3 4

SPI_DO

SPI_DI

Command

MSB

HIGH IMPEDANCE

USB5537B Datasheet(PDF) 17 Page - Microchip Technology