24CW128X HAR question

[soonc]

I decide to use a small SOT23-5 eeprom. The Microchip part number is:
24CW1280T-I/OT

Other than the HAR register the timing seems to be about the same as more conventional 24LC256 versions.

The big difference is the Hardware Address register which allows setting the Device Address A2,A1,A0 bits by writing to the HAR register so that up to 8 devices can be on the same bus.

Reading the datasheet I concluded the base address 0XA0 is a valid address and proceeded to use some CCS example code to read and write data.

The first attempt does not work, Read just returns 0XFF.

I coded PCM Programmer's I2C bus scan code and it returns Address 0XA0 so all appears to be correct with regards to the basic I2C on this hardware.

I'm using CCS I2C software library, which is also working well on the same hardware for a different device at a different address.

I have 3K3 pull up resistors on the SDA and SCL as I said it's working OK on a different part same hardware.

My questions are:
1) Is it a requirement that the HAR register MUST be written to at least once even when using the default Device Address of 0XA0 ?

2) Has anyone used the 24CW series eeprom and is there anything special about it ?

Thanks in advance for any help.

[Ttelmah]

Which example driver are you using?.
Are you pausing after power up?. The chip needs you to wait for at least
Tpup after power is applied before it can work (100uSec).

[soonc]

[Ttelmah]

Well done.