3.2 Polling Operation Mode Functions

The SPI Transfer Elementary Function

The function spi() is the elementary function that handles the SPI interface in polling mode. It sends a byte and stores the received one. Note that this function does not control the level of the chip select line. spi() is called from tx_spi() and rx_spi(). The function tx_spi() writes a byte on SPI and rx_spi() receives the byte.

Prototype: 

char spi(uint8_t data);
Figure 3-1. SPI Transfer Function Flowchart

The Read Status Register Function

The functions dataflash_read_status_register() and eeprom_read_status_register() perform an RDSR access. They return the access status value.

Prototype: 

uint8_t dataflash_read_status_register(void);
uint8_t eeprom_read_status_register(void);
Figure 3-2. Read Status Register Function Flowchart

The Single Byte Write Command

The function send_cmd() sends the single byte op_codes, such as WREN,WRDI, etc. The serial memory must be ready before performing the access.

Prototype:

void send_cmd(uint8_t opcode)
Figure 3-3. Send Command Flowchart

The Write Status Register Function

This function performs the RDSR access. It sends op_codes OP_EWSR: Enable Write Status Register and OP_WRSR: Write Status Register and then sends the data to be written to the status register.

Prototype:

void dataflash_write_status_register(uint8_t byte);
Figure 3-4. Write Status Register Function Flowchart