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ATUND
Associate
May 20, 2019
Question

How to read the data from M95256 EEPROM?

  • May 20, 2019
  • 2 replies
  • 2066 views

I'm using M95256 IC which is used as an external EEPROM for the controller. When i'm sending Read Status Register command i can see data from IC in receive buffer. But when i'm sending Read from Memory command, i get only 0xFF data in the buffer.I have checked the Status register after Write to memory command and the WIP = 0 and WEL=1 in the register. I'm not able to see the data on the oscilloscope as well even though i can see Read from memory command is getting transmitted in Tx Buffer as well as i can see it on oscilloscope.

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2 replies

Pierre P.
ST Employee
May 20, 2019

​Hello,

Please follow section 6.5 of datasheet attached.

Warning: Read operation can't be performed if a Write cycle is currently in progress.

Moreover, your status register value should be with WIP & WEL=0. I f WEL= 1 it means the write instruction didn't success.

0xFF correspond to the delivery state.

BR

EEPROM suPPort team

ATUND
ATUNDAuthor
Associate
May 20, 2019

Hi,

My instructions sequence is:

1.WRITE ENABLE

2.WRITE STATUS REGISTER

3.WRITE DISABLE

4.READ STATUS REGISTER

5.WRITE ENABLE

6.WRITE MEMORY ARRAY

7.WRITE DISABLE

8.READ STATUS REGISTER

9.READ FROM MEMORY ARRAY

I have added delay of 5ms in between the instructions. But still the value of status register remains same i.e. WIP=0 and WEL=1.

ATUND
ATUNDAuthor
Associate
May 20, 2019

Hi,

My instructions sequence is:

1.WRITE ENABLE

2.WRITE STATUS REGISTER

3.WRITE DISABLE

4.READ STATUS REGISTER

5.WRITE ENABLE

6.WRITE MEMORY ARRAY

7.WRITE DISABLE

8.READ STATUS REGISTER

9.READ FROM MEMORY ARRAY

I have added delay of 5ms in between the instructions. But still the value of status register remains same i.e. WIP=0 and WEL=1.