Can I get the NI USB-8451 to act as listener on an i2c bus?

[cmh]

Hi all,

I asked the following question on NI:s forum without any response so I hope for better luck here.

I have a question regarding communicating on an i2c bus. I'm new to i2c so please bear with me if I haven't got the concepts right.

I have an i2c bus where I want to remove one device and instead use the NI USB-8451 to simulate the device. Basically when a message appears on the bus with a specific address I should answer it. I think that the communication is set up in a multi-master request-reply fashion in the sense that the bus is not "locked" while a master unit is waiting for a reply. Instead each message consist of an address, the address the message came from, message length, payload data and a checksum. If a device recieves a message it can find out who sent the message and send a reply.

When I read about the USB-8451 it says that it can not act as a slave. Does this mean that I can not do what I want using this module? Can I setup the USB-8451 to monitor the bus for messages with a certain address? If not, is there any other NI module I could use?

Best regards

Martin

[Daklu]

Can I setup the USB-8451 to monitor the bus for messages with a certain address? If not, is there any other NI module I could use?

It's been a couple years since I used the 8451, but last time I looked into it you could not easily do it. You might be able to do it if you implemented a whole I2C bit banging library, but that kind of defeats the purpose. I switched over to the Total Phase Aardvark for that very reason. As an added bonus the Aardvark is cheaper and supports 400 kb/s whereas the 8451 only went up to 250(?) kb/s.

[cmh]

It's been a couple years since I used the 8451, but last time I looked into it you could not easily do it. You might be able to do it if you implemented a whole I2C bit banging library, but that kind of defeats the purpose. I switched over to the Total Phase Aardvark for that very reason. As an added bonus the Aardvark is cheaper and supports 400 kb/s whereas the 8451 only went up to 250(?) kb/s.

The Aardvark indeed seems to suit my purposes much better. Thanks for the info.