SPI FLASH read/write

Discussion in 'Embedded Systems and Microcontrollers' started by giuseppemg, Dec 3, 2010.

  1. giuseppemg

    Thread Starter New Member

    Oct 24, 2010
    5
    0
    Hi,
    i've a willem programmer (http://www.sivava.com/).
    I must read and write some SPI Flash memory (bios pc/hdd memory).
    This memory for example are: AT25F512 or W25X80A.
    The programmer have a ICSP connector with:
    VPP
    VCC
    GND
    RB7
    RB6
    I've connect all pin as in the attach image.
    But i can't read the chip.

    Can you help me?

    Thank you
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    You're going to have a hard time reading the chip with chip select at VPP. I guess if Vpp can be set to GND then it might be possible, but in order to start a transaction it must go low and to finish a transaction it must go high again.
     
  3. giuseppemg

    Thread Starter New Member

    Oct 24, 2010
    5
    0
    You are right.
    If i use gnd with CS i can't read.
    Can i use vcc with a pull-up resistors?
    Can you help me?

    Thank you.
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    You need to connect CS* to a port pin. You also need to connect SI pin 5 to a port pin. If you have read the datasheet you will realize that you have to be able to write data to the device in order to read data back from the device. Come back when you have read the datasheet and understand how a read transaction works. OK?
     
  5. giuseppemg

    Thread Starter New Member

    Oct 24, 2010
    5
    0
    OK,
    i've read the datasheet.
    The SI pin 5 must be connect to RB7. But can be a noise between SI and SO? In datasheet when SI write SO is high and when SO read SI is high so can't be noise if connect SO and SI to RB7?

    CS must be high when go on and low when start to read or program. I've connect CS in pull-down to GND. But how can change from high to low?

    thank you.
     
  6. migwell2

    New Member

    Apr 22, 2012
    1
    0
    Hi Giuseppemg,
    do you have found a solution ?
    I have the same problem, I have read the datasheet but I still confused...
     
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