NXT + RCX daisy chain, hardware questions

[DPyro]

Hi, I am currently trying to have one NXT and two RCX's communicate with each other. Right now, I am thinking of a daisy chain, where two sensor ports are used (data line and clock line) and using the NXT as a master with serial transfer. The clock line will be on the first port/sensor and the data line will be on the second port/sensor. In order to make it work, I will have to emulate some things in software, so I have a few questions =)

1) How fast can the NXT and RCX switch threads (millisecond wise)?
2) How fast can the NXT and RCX activate/passivate a sensor? Do the methods block or return instantly?
3) Is it even possible to do what I'm thinking? =P

Many thanks!

[bbagnall]

Here's a reply from Charles Manning who is working on I2C support at the moment:

The adapter's main mission is to allow you to hook up an RCX sensor to an NXT.

No doubt some sort of comms is possible, but that might require considerable effort in software.

It should be possible to implement some sort of I2C link.

It would also be possible (in theory anyway) to use the high speed link on input 4 as a UART. Slow it down a bit and use IR.

It is also possible to re-jig any of the other NXT ports as soft UARTs up to 19200 or so. Not a lot of effort (simpler than I2C).

Possible yes, easy no.

I would also add that you can use the Mindsensors.com IRLink to communicate with the RCX and control motors. I've got a basic driver for this adapter in iCommand and we'll port it to NXJ when we have I2C support.

[zimingw]

Hi BB,

Glad to hear you will port IRLink to NXJ! I saw it's in iCommand 0.6 api but not in NXJ 0.4 yet. Any plan when it will be?

Are you also going to add support for PF Motors?

Regards

[lawrie]

Now that gloomyandy seems to have a fix for I2C writes, I might have another look at the IRLink and other sensors that needed I2C writes.

I will also investigate the PF motors.

[lawrie]

The development version of leJOS in the SVN repository now has an RCXLink class that supports some of the functions of the mindsensors NRLinx-Nx adapter. I have not tried a HiTechnic IRLink yet.

Please let me know what type of communication you want to do between the RCX and the NXT.

[bbagnall]

The development version of leJOS in the SVN repository now has an RCXLink class that supports some of the functions of the mindsensors NRLinx-Nx adapter. I have not tried a HiTechnic IRLink yet.

Please let me know what type of communication you want to do between the RCX and the NXT.

Well in my humble opinion it should mimic the functionality of the iCommand IRLink class, or at least use that as a launching point for better ideas. It's very easy to take the iCommand code and adapt it for NXJ.