introduction

There was a spi nand flash in the device I used in the last article, but I couldn't find a program that can read and write spi nand flash, so I'm trying to make it.

Connect Flash to Raspberry Pi

I removed the spi nand flash from the device in the previous article.

I soldered the flash to the dip package conversion board and connected it to the raspberry pi.

The pinout is the same as the spi nor flash, so I connected it the same way.

I decided to read the data using python and spidev library.

First, I enabled the spi interface in raspi-config.

And read the id of the chip to see if the flash is working properly.

I looked in the datasheet and the instruction to read the id is 0x9f.

I wrote and tested a code that transmits 0x9f and receives data.

import spidev

spi = spidev.SpiDev()

spi.open(0,0)
spi.mode = 0
spi.max_speed_hz = 1000000

data = spi.xfer2([0x9F] + [0x00]*4)
print([hex(x) for x in data[2:]])

The values were output according to the datasheet.

read flash

I wrote and tested the code that sends the read_data instruction and receives data.

import spidev

spi = spidev.SpiDev()

spi.open(0,0)
spi.max_speed_hz = 1000000

data = spi.xfer3([0x03, 0x00] + [0x00] * 2112)

with open("test.bin", "wb") as f:
    f.write(bytes(data))

When I check the data, it seems that the memory contents are printed out well.

But it doesn't seem to dump properly after 1070 bytes.

Conclusion

Next time, I'll check what the problem is and dump the entire memory.

I will also look into the spi nand flash driver in the kernel.