STM32 External NOR Flash - SST26VF064B

[GeorgePriestner-Eaton]

Hello,

I'm hoping to get some help on configuring an external flash chip using zephyr dts.

I'm attempting to configure an external SPI NOR flash chip with an STM32f429zi development board. I have added the following to my overlay file:

    soc {
        /* Use STM32F429 spi2 */
        spi2: spi@40003800 {
            status = "okay";
            pinctrl-0 = < &spi2_sck_pb13 &spi2_miso_pc2 &spi2_mosi_pb15 &spi2_nss_pb12 >; 
            pinctrl-names = "default";
            clock-frequency = <500000>; /* SPI clock speed */ /* min freq = 164062, max = 21000000 */
            /* Configure external NOR flash with jedec compatibility */
            spi_flash: SST26VF064B@0 {
                compatible = "jedec,spi-nor";
                status = "okay";
                reg = <0>;
                label = "SST26VF064B";
                spi-max-frequency = <500000>; /* .5 Mhz */
                jedec-id = [ bf 26 06 ]; /* JEDEC ID as manufacturer ID, memory type, memory density */ //BF 26 06
                sfdp-bfp = [ FD 20 F1 FF  FF FF FF 03  44 EB 08 6B  08 3B 80 BB  FE FF FF FF  FF FF 00 FF  FF FF 44 0B  0C 20 0D D8  0F D8 10 D8  20 91 48 24  80 6F 1D 81  ED 0F 77 38  30 B0 30 B0  F7 FF FF FF  29 C2 5C FF  F0 30 C0 80 ];
                size = <0x4000000>; /* Flash size in bits */
            };
        };
    };

in the final zephyr.dts file, the spi2 is configured as such:

		spi2: spi@40003800 {
			compatible = "st,stm32-spi";
			#address-cells = < 0x1 >;
			#size-cells = < 0x0 >;
			reg = < 0x40003800 0x400 >;
			clocks = < &rcc 0x2 0x4000 >;
			interrupts = < 0x24 0x5 >;
			status = "okay";
			label = "SPI_2";
			pinctrl-0 = < &spi2_sck_pb13 &spi2_miso_pc2 &spi2_mosi_pb15 &spi2_nss_pb12 >;
			pinctrl-names = "default";
			clock-frequency = < 0x7a120 >;
			spi_flash: SST26VF064B@0 {
				compatible = "jedec,spi-nor";
				status = "okay";
				reg = < 0x0 >;
				label = "SST26VF064B";
				spi-max-frequency = < 0x7a120 >;
				jedec-id = [ BF 26 06 ];
				sfdp-bfp = [ FD 20 F1 FF FF FF FF 03 44 EB 08 6B 08 3B 80 BB FE FF FF FF FF FF 00 FF FF FF 44 0B 0C 20 0D D8 0F D8 10 D8 20 91 48 24 80 6F 1D 81 ED 0F 77 38 30 B0 30 B0 F7 FF FF FF 29 C2 5C FF F0 30 C0 80 ];
				size = < 0x4000000 >;
			};
		};

and added the following lines to my prj.conf:

CONFIG_SPI=y
CONFIG_SPI_NOR=y
CONFIG_FLASH_JESD216_API=y

The driver seemingly gets initialised correctly, no error is returned when erasing, writing, or reading. However when attempt to read data from the flash I only get ff's returned in the read buffer.

Below is the output on the UART from my test program. I'm just attempting to write a 5 byte buffer to the flash, then read it back.

SPI Flash Device: SST26VF064B
SST26VF064B page count: 128
Using SST26VF064B, chip size: 8388608 bytes (page: 65536)
Minimum write block size: 1
Jedec ID: [ be 10 37 ]
SPI Flash read err: 0

SPI read_data[0]: ff
SPI read_data[1]: ff
SPI read_data[2]: ff
SPI read_data[3]: ff
SPI read_data[4]: ff
SPI Flash erase err: 0

SPI Flash write err: 0

SPI Flash read err: 0

SPI read_data[0]: ff
SPI read_data[1]: ff
SPI read_data[2]: ff
SPI read_data[3]: ff
SPI read_data[4]: ff

Am I doing anything obviously wrong or missing something? Does my overlay file look correct?

Many thanks in advance.

[ndrs-pst]

@GeorgePriestner-Eaton
It appears that the drive is initializing correctly, so the issue might lie within the test program, have you tried using flash_shell.c for read/write operations (with CONFIG_FLASH_SHELL=y enabled)?