EEPROM Microchip 25LC040AT-E/OT SPI Reading

[Cisco]

Dear all,

I have to write 4 data bytes on an EEPROM, and read the full EEPROM (512 Bytes) with a NI USB-8452 SPI Interface. 

The EEPROM component is a Microchip 25LC040AT-E/OT

I've tested the examples (General SPI Write/Read and General SPI Write/Read Script) but impossible to read something else 0...

I've connected a scope meter to acquire signals when readin 4 bytes, I obtain this:

(yellow CS, green MISO, blue CLK, red MOSI)

I don't understand why the levels of MISO, MISO and CLK are not between 0 and 3.3V, like CS. Is it normal? A colleague has done the measurement with another SPI interface, for the same measurement the curves are completely different:

I try to understand where is the problem by me...

Power supply (external): 3.3V

I/O Voltage Level: 3.3V

Chip Select: 0

Clock Rate: 40kHz

Clock Polarity: 0 (Idel Low)

Clock Phase: 0(First Edge)

Number of Bits Per Sample: 8

Data Address Width: 1 Byte

Data Address Endianness: Big Endian (MSB 1st)

Page Size: 16 Bytes

I've connected CS, MISO, MOSI and CLK, plus GND of SPI Interface on the GND of my PCB. 

First, I've tried to read 4 Bytes, starting adress 0x25. Its what I've measured with scope meter. I normally should read something different from 4 Byes of 0x00...

I work with LabVIEW 2018 SP1 and NI-845x 19.0 and a W10 Computer (64 bits).

What do you think I've made wrong??

Thank you per advance!

Regards

[Eloise]

Hello Francis,

First of all, sorry for the late answer.

Have you resolved this issue ?

If not, have you put pull-down resistor ?

[Cisco]

Hello @Eloise,

Yes it is solved, it was effectively linked to pull-down resistor; vi was OK.

Regards,