This is the pinout I have for the flash memory W25Q128FV which I'm trying to interact with

enter image description here enter image description here

I'm trying to control it with a raspberry pi 3 B+.

Here's how I wired everything:

VCC - 3.3v
HOLD - 3.3v

CS is in GND because datasheet says that in LOW, we can write/read from the chip, but I think this is wrong. I need to connect this to some raspberry pi pin that maybe is controlled by wiring pi.

I also enabled spi on raspberry and I'm using the library wiringPi with channel 0.

I'm writing like this (Rust code linked against -lwiringPi):

pub fn read_status_register_3(&self) -> [u8;2]{
    let mut slice :[u8;2] = [0;2];
    let mut data: [::std::os::raw::c_char; 2] = [0;2];
    data[0] = 0x11;
    let mut _r: i32 = 0;
    _r = unsafe{wiringPiSPIDataRW (self.spi_channel,data.as_mut_ptr(), data.len() as i32)};

but I get data to be all 0. I suspect something is wrong but I don't know if it's on the chip, on the wiring or on the software. This is a brand new chip by the way.

datasheet link: http://www.xmcwh.com/Uploads/2020-09-03/5f50d26953af2.pdf

Here's my Rust code with everything ready to test and dockerized, just ./run.sh, compile the Wiringpi/wiringpi with ./build and cargo run in w25qxx_spi: https://github.com/lucaszanella/w25qxx_spi/blob/b652db39d83521d7f018bd254c1b3dca03549f00/w25qxx_spi/src/w25q.rs

  • You're probably aware that wiringPi has been deprecated. It still works - at least I still use it occasionally, but if you've not used it much, you should be aaware that is uses a unique numbering scheme for GPIO pins. You can print those from wiringPi, or use this tool, and hover over the pin to see the "tool tip".
    – Seamus
    Commented Mar 20, 2021 at 6:35
  • I suggest you get it working using a more supported environment such as C or Python. When that is working port the code to Rust.
    – joan
    Commented Mar 20, 2021 at 8:43

1 Answer 1


Found the problem. Have to connecto CS to SPICS0 which is a pin on the rpi

  • 1
    Congratulations! Please "accept" your answer as the correct one when you are able. his will prevent the question from becoming a zombie :)
    – Seamus
    Commented Mar 21, 2021 at 5:28

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