Having trouble reading a 24c04.

[delambo]

I have tried on both my SEEprog and my Willem but neither will work. I have tried to read and write a 24c02 on both and they read and wrote perfectly on both proggers. Since the 24c02 is a dil and the 24c04 is a soic I decided to check my test clip was all ok and correct by reading and writing a 93c46 which worked fine on both machines. Concerned the device I was trying to read was faulty I tried to read another device the same from another similar ECU but no joy there either. Since I was trying to read in circuit I decided to desolder one of the devices and read it on the bench to see if this made a difference but it didnt.

When I read it on my SEEprog it indicates a correct read but the buffer is blank, however when I use my Willem I get the message "No ACK Device Command". I have had a look at a datasheet and found this quote (amongst others) relating to the ACK or acknowledge command.

Originally Posted by datasheet

Acknowledge in Read Mode. In all read modes
the ST24/25x04 wait for an acknowledge during the
9th bit time. If the master does not pull the SDA line
low during this time, the ST24/25x04 terminate the
data transfer and switches to a standby state.

Any advise, I am new to ACK commands.

[jakeyfly]

daft sugestion here mate but havent got your clip set up for rotated 93c46 have you?
if thats ok your eep could well be faulty but strange for 2 to go down, i have never had a problem reading or writing a 24cxx eeprom, well i have but only with bad connections
you could have a look at the sda pin with your scope and see whats going on, or you can post it up to me and i will have a go
cheers