Multiple I2C

Question

I have 2 separate I2C chain with 8 identical IC in each ones. Is it possible to drive both with same NI USB-8451 - of course with some switches, let say CMOS Analog Multiplexer. I can use IO port on NI USB-8451 to drive Mux, but how to avoid timing problem. With other words how to achieve that IO command wait until I2C Read or Write is ended (without extensive Wait in LabView execution).
I haven’t yet NI USB-8451 so I can’t test and must to know how to solve that problem before buy hardware.

Answer 1

Hi Oldi,
Our I2C Box can serve 8 identical devices, for example EEPROMS because the address uses the first 4 bits for Hardware Typ Configuration and the rest 3 bits for addressing. So if your 8 chips are identical it should work.
For 8 more chips there are three scenarios:
1. the second 8 chips are different in hardware (no EEPROMS). In this case it should work to connect them too, because the first  four address bits changes.
2. you use a second 8452 box for the second 8 chips.
3. you use a digital line from the 8451 to control a switch or relay which switches between the two 8 chipsets. Both sets should have the same address. The API can control both DIO and I2C to change the Chipsets on the fly.
DirkW