Atmel Flash EEPROM AT45DB interface

Data Structures
struct	bufmgr_t

Macros
#define	AT45DB_CS   1
#define	AT45DB_STATUS_REG   0xD7
#define	AT45DB_BLOCK_ERASE   0x50
#define	AT45DB_PAGE_ERASE   0x81
#define	AT45DB_PAGE_PROGRAM_1   0x82
#define	AT45DB_PAGE_PROGRAM_2   0x85
#define	AT45DB_BUFFER_1   0x84
#define	AT45DB_BUFFER_2   0x87
#define	AT45DB_BUF_1_TO_PAGE   0x83
#define	AT45DB_BUF_2_TO_PAGE   0x86
#define	AT45DB_PAGE_READ   0xD2
#define	AT45DB_PAGE_TO_BUF   0x55
#define	AT45DB_READ_BUFFER   0xD6

Functions
int8_t	at45db_init (void)
	Initialize the AT45DBxx1 Flash EEPROM. More...
void	at45db_erase_chip (void)
	This function erases the whole chip. More...
void	at45db_erase_block (uint16_t addr)
	This function erases one block (4 Kbytes) More...
void	at45db_erase_page (uint16_t addr)
	This function erases one page e.g. More...
void	at45db_write_buffer (uint16_t addr, uint8_t *buffer, uint16_t bytes)
	This function writes bytes to the active buffer, while the buffer management is done automatically. More...
void	at45db_buffer_to_page (uint16_t addr)
	This function copies the active buffer into the Flash EEPROM page. More...
void	at45db_write_page (uint16_t p_addr, uint16_t b_addr, uint8_t *buffer, uint16_t bytes)
	This function copies the data from the the pointer into the buffer, erases the EEPROM page and flashes the new content directly into the page. More...
void	at45db_read_page_buffered (uint16_t p_addr, uint16_t b_addr, uint8_t *buffer, uint16_t bytes)
	Bytes can be read via buffer from a Flash EEPROM page. More...
void	at45db_read_page_bypassed (uint16_t p_addr, uint16_t b_addr, uint8_t *buffer, uint16_t bytes)
	Bytes can be read direct (bypassed) from a Flash EEPROM page. More...
void	at45db_page_to_buf (uint16_t addr)
	Copies the given page into the buffer 2. More...
void	at45db_read_buffer (uint16_t b_addr, uint8_t *buffer, uint16_t bytes)
	This function readouts the buffer 2 data. More...
void	at45db_write_cmd (uint8_t *cmd)
	The command word of the AT45DBxx1 normally consists of 4 bytes. More...
void	at45db_busy_wait (void)
	This function waits until the busy flag of the status register is set, to detect when the AT45DBxx1 device is ready to receive new commands.

Detailed Description

A fixed Flash EEPROM is always good to store some data. Furthermore in this project environment, the AT45DBxx1 will be used as a hardware interface between the boot section and the application section.

Note

All functions will return immediately if flash is uninitialized or initialization failed.

The function of the AT45DBxx1 is a little bit different compared to an SD-Card. The basic idea of the SD-Card is, to store one block (512Byte) into a local buffer an transfer the whole block via SPI to the SD-Card. The AT45DBxx1 has two page buffer, where the data can be collected by sending a byte via SPI to one of these buffers. If a buffer is filled, only a command is necessary and the AT45DBxx1 will copy the buffer into the flash section. To avoid latency, it is possible (and implemented) to switch between the page buffers.

Macro Definition Documentation

#define AT45DB_BLOCK_ERASE   0x50

Block Erase Opcode

Definition at line 92 of file at45db.h.

Referenced by at45db_erase_block().

#define AT45DB_BUF_1_TO_PAGE   0x83

Copy Buffer 1 to page Opcode

Definition at line 118 of file at45db.h.

Referenced by at45db_init().

#define AT45DB_BUF_2_TO_PAGE   0x86

Copy Buffer 2 to page Opcode

Definition at line 122 of file at45db.h.

Referenced by at45db_init().

#define AT45DB_BUFFER_1   0x84

Write byte(s) to buffer 1 opcode

Definition at line 109 of file at45db.h.

Referenced by at45db_init().

#define AT45DB_BUFFER_2   0x87

Write byte(s) to buffer 2 opcode

Definition at line 113 of file at45db.h.

Referenced by at45db_init().

#define AT45DB_CS   1

SPI device order. The chip select number where the AT45DBxx1 Flash EEPROM is connected to the BCD-decimal decoder

Definition at line 79 of file at45db.h.

Referenced by at45db_buffer_to_page(), at45db_busy_wait(), at45db_erase_block(), at45db_erase_chip(), at45db_erase_page(), at45db_init(), at45db_page_to_buf(), at45db_read_buffer(), at45db_read_page_bypassed(), at45db_write_buffer(), at45db_write_cmd(), and at45db_write_page().

#define AT45DB_PAGE_ERASE   0x81

Page Erase Opcode

Definition at line 96 of file at45db.h.

Referenced by at45db_erase_page().

#define AT45DB_PAGE_PROGRAM_1   0x82

Main Memory Page Program Buffer 1

Definition at line 100 of file at45db.h.

Referenced by at45db_init().

#define AT45DB_PAGE_PROGRAM_2   0x85

Main Memory Page Program Buffer 2

Definition at line 104 of file at45db.h.

Referenced by at45db_init().

#define AT45DB_PAGE_READ   0xD2

Read direct from Flash EEPROM page Opcode

Definition at line 126 of file at45db.h.

Referenced by at45db_read_page_bypassed().

#define AT45DB_PAGE_TO_BUF   0x55

Transfer page to buffer 2 Opcode

Note

Only Buffer 2 is used to readout a page, because the read respectively transfer latency is only about 200us

Definition at line 133 of file at45db.h.

Referenced by at45db_page_to_buf().

#define AT45DB_READ_BUFFER   0xD6

Read buffer 2 opcode

Note

Only Buffer 2 is used to readout a page, because the read respectively transfer latency is only about 200us

Definition at line 139 of file at45db.h.

Referenced by at45db_read_buffer().

#define AT45DB_STATUS_REG   0xD7

Status Register Address. Bit 7 signalizes if the device is busy.

• 1 : not busy
• 0 : busy

Definition at line 87 of file at45db.h.

Referenced by at45db_busy_wait().

Function Documentation

void at45db_buffer_to_page

(

uint16_t

addr

)

This function copies the active buffer into the Flash EEPROM page.

Moreover it switches the active buffer to avoid latency.

Parameters

addr	page address e.g. AT45DB161 (0 ... 4095)

Definition at line 159 of file at45db.c.

References bufmgr_t::active_buffer, at45db_busy_wait(), AT45DB_CS, at45db_write_cmd(), bufmgr_t::buf_to_page_addr, and mspi_chip_release().

void at45db_erase_block

(

uint16_t

addr

)

This function erases one block (4 Kbytes)

Parameters

addr	block address e.g. AT45DB161 (0 ... 511)

Note

The time to erase one block can take up to 45ms - 100ms!

Definition at line 114 of file at45db.c.

References AT45DB_BLOCK_ERASE, at45db_busy_wait(), AT45DB_CS, at45db_write_cmd(), mspi_chip_release(), and mspi_chip_select().

void at45db_erase_chip

(

void

)

This function erases the whole chip.

Note

The time to erase the whole chip can take up to 20sec!

Definition at line 101 of file at45db.c.

References at45db_busy_wait(), AT45DB_CS, at45db_write_cmd(), mspi_chip_release(), and mspi_chip_select().

void at45db_erase_page

(

uint16_t

addr

)

This function erases one page e.g.

AT45DB161 (512 bytes)

Parameters

addr	page address e.g. AT45DB161 (0 ... 4095)

Note

The time to erase one bock can take up to 15ms - 35ms!

Definition at line 128 of file at45db.c.

References at45db_busy_wait(), AT45DB_CS, AT45DB_PAGE_ERASE, at45db_write_cmd(), mspi_chip_release(), and mspi_chip_select().

int8_t at45db_init

(

void

)

Initialize the AT45DBxx1 Flash EEPROM.

Return values

0	at45db available
-1	at45db not available

Note

No special settings are necessary to initialize the Flash memory. The standard data flash page size is 528Byte e.g. AT45DB161

Definition at line 68 of file at45db.c.

References bufmgr_t::active_buffer, AT45DB_BUF_1_TO_PAGE, AT45DB_BUF_2_TO_PAGE, AT45DB_BUFFER_1, AT45DB_BUFFER_2, AT45DB_CS, AT45DB_PAGE_PROGRAM_1, AT45DB_PAGE_PROGRAM_2, bufmgr_t::buf_to_page_addr, bufmgr_t::buffer_addr, MSPI_BAUD_MAX, mspi_chip_release(), mspi_chip_select(), mspi_init(), MSPI_MODE_3, mspi_transceive(), and bufmgr_t::page_program.

void at45db_page_to_buf

(

uint16_t

addr

)

Copies the given page into the buffer 2.

Note

Only Buffer 2 is used to readout a page, because the read respectively transfer latency is only about 200us

Parameters

addr	page address e.g. AT45DB161 (0 - 4095)

Definition at line 231 of file at45db.c.

References at45db_busy_wait(), AT45DB_CS, AT45DB_PAGE_TO_BUF, at45db_write_cmd(), and mspi_chip_release().

Referenced by at45db_read_page_buffered().

void at45db_read_buffer	(	uint16_t	b_addr,
		uint8_t *	buffer,
		uint16_t	bytes
	)

This function readouts the buffer 2 data.

Parameters

b_addr	byte address within the page e.g. AT45DB161 (0 - 527)
*buffer	Pointer to local byte buffer
bytes	Number of bytes (e.g. byte buffer size) which have to be read to the local byte buffer

Definition at line 249 of file at45db.c.

References at45db_busy_wait(), AT45DB_CS, AT45DB_READ_BUFFER, at45db_write_cmd(), mspi_chip_release(), and mspi_transceive().

Referenced by at45db_read_page_buffered().

void at45db_read_page_buffered	(	uint16_t	p_addr,
		uint16_t	b_addr,
		uint8_t *	buffer,
		uint16_t	bytes
	)

Bytes can be read via buffer from a Flash EEPROM page.

With this function you select the page, the start byte within the page and the number of bytes you want to read.

Parameters

p_addr	page address e.g. AT45DB161 (0 - 4095)
b_addr	byte address within the page e.g. AT45DB161 (0 - 527)
*buffer	Pointer to local byte buffer
bytes	Number of bytes (e.g. byte buffer size) which have to be read to the local byte buffer

Definition at line 196 of file at45db.c.

References at45db_busy_wait(), at45db_page_to_buf(), and at45db_read_buffer().

void at45db_read_page_bypassed	(	uint16_t	p_addr,
		uint16_t	b_addr,
		uint8_t *	buffer,
		uint16_t	bytes
	)

Bytes can be read direct (bypassed) from a Flash EEPROM page.

With this function you select the page, the start byte within the page and the number of bytes you want to read.

Parameters

p_addr	page address e.g. AT45DB161 (0 - 4095)
b_addr	byte address within the page e.g. AT45DB161 (0 - 527)
*buffer	Pointer to local byte buffer
bytes	Number of bytes (e.g. byte buffer size) which have to be read to the local byte buffer

Definition at line 206 of file at45db.c.

References at45db_busy_wait(), AT45DB_CS, AT45DB_PAGE_READ, at45db_write_cmd(), mspi_chip_release(), and mspi_transceive().

void at45db_write_buffer	(	uint16_t	addr,
		uint8_t *	buffer,
		uint16_t	bytes
	)

This function writes bytes to the active buffer, while the buffer management is done automatically.

Parameters

addr	Byte address within the buffer e.g. AT45DB161 (0 ... 527)
*buffer	Pointer to local byte buffer
bytes	Number of bytes (e.g. byte buffer size) which have to be written to the active buffer

Definition at line 142 of file at45db.c.

References bufmgr_t::active_buffer, AT45DB_CS, at45db_write_cmd(), bufmgr_t::buffer_addr, mspi_chip_release(), and mspi_transceive().

void at45db_write_cmd

(

uint8_t *

cmd

)

The command word of the AT45DBxx1 normally consists of 4 bytes.

This function enables the chip select and sends the command (opcode + address information) to the AT45DBxx1.

Parameters

*cmd	Pointer to the 4 byte command array

Definition at line 265 of file at45db.c.

References AT45DB_CS, mspi_chip_select(), and mspi_transceive().

Referenced by at45db_buffer_to_page(), at45db_erase_block(), at45db_erase_chip(), at45db_erase_page(), at45db_page_to_buf(), at45db_read_buffer(), at45db_read_page_bypassed(), at45db_write_buffer(), and at45db_write_page().

void at45db_write_page	(	uint16_t	p_addr,
		uint16_t	b_addr,
		uint8_t *	buffer,
		uint16_t	bytes
	)

This function copies the data from the the pointer into the buffer, erases the EEPROM page and flashes the new content directly into the page.

Parameters

p_addr	page address e.g. AT45DB161 (0 - 4095)
b_addr	byte address within the page e.g. AT45DB161 (0 - 527)
*buffer	Pointer to local byte buffer
bytes	Number of bytes (e.g. byte buffer size) which have to be read to the local byte buffer

Definition at line 174 of file at45db.c.

References bufmgr_t::active_buffer, AT45DB_CS, at45db_write_cmd(), mspi_chip_release(), mspi_transceive(), and bufmgr_t::page_program.