GAL20V8

[PhilArqiva]

Unfortunately our company still uses GAL chips in some telemetry equipment. The chips are being used in an I/O card in between the processor card and the main I/O chips. The problem we have is that something happens with a particular GAL chip, it seems to have failed by stopping the CPU from booting up. I can take known working chip, copy it into another chip of the same type and the chip won't work, the two chips verify okay, I can take another faulty chip without blanking it, it will verify okay against working chip. The GAL chips being used are Latice GAL20V8A and NS GAL20V8, we cannot get any of these to work, even though they verify okay. Unfortunately we only have a working chip as our source code and to verify against, this may be the problem, or I am doing something wrong with the programmer. We are using a Dataman 448pro programmer. What am I doing wrong, any ideas?

[Dataman (Neil Parker)]

Hello PhilArqiva,

Both of these chips have a security fuse, therefore if set, the read procedure will only get invalid data from the chip.

Are you sure these devices are not read-protected?

[PhilArqiva]

Thank you for getting back to me. How would you know whether a device has had the security bits enabled using a dataman programmer?

[Dataman (Neil Parker)]

Hello PhilArqiva,

After READing a protected device the buffer content will usually be all FFh or 00h.

[PhilArqiva]

Hi Neil

We don't get that, we see what looks like a HEX file back from the chip. We have also tried different manufacturers of the GALs too, we get different check sums, but I suppose that's because the different chips have different algorithm's to program them.

Many thanks