Mindboards

Hi I have built Daniele Benedettelli version of Jonny 5 NXT, I had 1 NXT kit, and I purchased a additional brick and motors and several required parts, it has been sitting for a while and now. Recently I want to build the remote control which needs yet another NXT brick and 2 more motors. I saw that Lego are now bringing out the EV3, so instead of purchasing another NXT brick and motors, I may get the EV3 kit.

Would I then be able to use the EV3 brick as the main brick on Johnny 5 and use my iphone as the remote control? (after programming)
Can the EV3 brick be used to interface to the 2nd NXT Brick to control the rest of the motors?

Original Johnny 5 has 6 motors in use with 2 NXT bricks. I replace the main NXT brick with the EV3 brick.

I too am interested in this idea, if I understand your question - can an EV3 and an NXT be connected using the
port 4 high speed RS485 connection? And to expand your question, can the same messages be sent between the
EV3 and NXT as between 2 NXTs, using port 4, using NXC on the NXT and ??? on the EV3? I have expanded on
Benedettelli's ideas so I can send a larger number of messages, and plan (hope) to use this in my next robot
with an NXT and an EV3. Thanks for any ideas and clarifications.

AFAIK the EV3 does not support RS485. With very minimal additional HW, RS485 should be possible, but it would require some SW hacking (I have no idea what would be involved, and it would depend on the level you did it at). The EV3 uses TTL UART as it's primary sensor communication protocol. If you used a MAX485 or similar transceiver, you could convert the TTL UART into RS485 UART, and you could theoretically use sensor pin 1 for direction control (in order for the NXT ultrasonic sensor to work, the EV3 must be able to pull sensor pin 1 to the battery voltage).

And I guess this begs the question, is there a way for direct connection communications between an
EV3 and an NXT, both in the same robot, without soldering inside the P-brick? I want to reserve Bluetooth
for communication to other robots. (Actually, I expect I may learn this Sept 1, when I get my EV3.) I think
I read where the EV3 has more USB capabilities. Would this be useful in communicating between an EV3
and an NXT running NXC? Or is the answer, any robot requiring 2 P-bricks, will have 2 NXTs or 2 EV3s,
not a mixture? I'm comfortable soldering cables, e.g. to connect a PF motor to an NXT, but not to solder
or unsolder anything inside a P-brick.
Thanks for any ideas.
Howard

As far as the HW goes, adding a MAX485 would be external to the EV3. In order to actually make it work though, you'd need an IO to control the direction (perhaps sensor pin 1), SW access to it, as well as SW access to the UART (for communication).

The EV3 has a USB host port. As far as the HW is concerned, you should be able to connect an NXT to the EV3 through USB. As far as drivers/SW is concerned, it might be very complicated to make them communicate.

Sorry to bump in, but I am thriving to discover in EV3 will be able to communicate with NXT! So we are talking about EV3 loosing RS485, but does it retain I2C?, as far as I remember NXT use I2C albeit a bit slow - does EV3 Still use I2C? If it does is there a way to interface the two brick using I2C so one brick (THE EV3) Send a packet of data - which in turn could be decoded to motor control?

The EV3 uses UART for sensor communication with the EV3 sensors, but it uses I2C for backwards compatibility with the NXT I2C sensors. The NXT (and I assume the EV3) I2C buses are master only. The default speed is about 9600bps.

Unless the EV3 supports I2C slave (I really doubt it), it would be impossible to make them communicate directly using I2C.

At some point in the future I plan to have an API that will enable programs running on the EV3 to send direct and system commands to an NXT connected via USB cable via which you could control motors and read sensor values without any program running on the NXT. There may be other means in the future for communicating back and forth between an EV3 and one or more NXTs but that is still a long way off, I think. I could be wrong.

John Hansen

John, this sounds cool if you need help, I am in if you give me some guidance - this will be a deal breaker, I currently have 4 NXT's 2 education, one retail, one brick by itself, and I am rubbing my hands to get them to work hand by hand with the EV3

afanofosc wrote:At some point in the future I plan to have an API that will enable programs running on the EV3 to send direct and system commands to an NXT connected via USB cable via which you could control motors and read sensor values without any program running on the NXT.
John Hansen

Did you make any progress with this? This seems like an incredibly useful function. I'm guessing it would need custom firmware running on the NXT.