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AT45 DataFlash driver sample

Overview

This sample shows how to use the AT45 family DataFlash driver and how to specify devicetree nodes that enable flash chip instances to be handled by the driver (an overlay with two sample nodes is provided). The sample writes a defined test region in the flash memory with bytes of increasing (and overflowing at the 8-bit range) values and then reads it back to check if the write was successful. The starting value is also increased in consecutive runs of the sample. Finally, the flash chip is put into low power state. In the default configuration, the AT45 flash driver is configured to use the Read-Modify-Write functionality of DataFlash chips and does not perform page erasing, as it is not needed in this case. This can be modified by simply disabling the SPI_FLASH_AT45_USE_READ_MODIFY_WRITE option.

Requirements

This sample has been tested on the NordicSemiconductor nRF9160 DK (nrf9160_pca10090) board with the AT45DB321E chip connected. It can be easily adjusted to be usable on other boards and with other AT45 family chips by just providing a corresponding overlay file.

Building and Running

The code can be found in samples/drivers/spi_flash_at45.

To build and flash the application:

west build -b nrf9160_pca10090 samples/drivers/spi_flash_at45
west flash

Sample Output

DataFlash sample app on nrf9160_pca10090
Using DATAFLASH_1, chip size: 4194304 bytes (page: 512)
Reading the first byte of the test region ... OK
Preparing test content starting with 0x01.
Writing the first half of the test region... OK
Writing the second half of the test region... OK
Reading the whole test region... OK
Checking the read content... OK
Putting the flash device into low power state... OK

The sample is supplied with the overlay file that specifies two instances of AT45 family chips but only the one labeled “DATAFLASH_1” is required for the sample to work. If the other chip is not connected, the following log message appears, but apart from that the behavior of the sample stays unaffected.

[00:00:00.000,000] <err> spi_flash_at45: Wrong JEDEC ID: ff ff ff, expected: 1f 24 00