Bluetooth NEQ6 control

[chrismills]

Hi all.

I've managed to build a bluetooth adapter for wireless control of my Skywatcher NEQ6. It is simply a cable replacement for the long USB lead and HiTecAstro USB EQDirect interface I was using before. Seems to work really well with Carte du Ciel and EQMOD ASCOM software.

Jury rigged on breadboard so no photos at the moment. It looks like a pile of spaghetti.

If anyone is interested I could supply instructions or probably build a batch of several. I think should come to about £20 each.

Chris

[Reggie]

Hi Chris, I've been looking at bluetooth modules too, like these, I think I know of a way to reprogram the firmware to give access to more pins on the units, if you want to pm me I'd be happy to discuss it.

I've been wondering which pin on the handset cable provides power to the handset, can't seem to find the info on the net though.

[Gina]

Congratulations on getting it all working

Maybe the stuff has improved but with the amount of trouble I've had in the past getting Bluetooth to work put me off plus I needed a cable duct to supply power to the mount etc. so putting USB cables through the same pipe was the easiest way to go.

[chrismills]

Thanks for the interest.

I appreciate that you still need some power supply to the scope which means running at least one cable, plus I'm still running a USB to control my camera and guiding setup. Still working on that!

In terms of connections, the setup I have plugs straight into the connector on the side of the telescope and replaces the handset. One of the pins from the scope supplies +12v DC which I have regulated down to +5v to supply the BlueTooth unit.

I can't exactly remember the pins off the top of my head so I'll post some more details later.

Chris

[Reggie]

Hi Chris, it's a great project, It's something i should've gotten round to ages ago, I wasn't criticising the build, just wondering which pin on the mount supplies 12v I'm now starting to wonder what kind of leeway there is for power consumption on the mounts psu? Looking at the handset they're using a 7805 to provide regulated voltage to the microcontroller, so there should be a few hundred milliamps.

Looking forward to seeing the details

Regards,

Reggie.

[chrisshillito]

The circuit for the RS232 EQDIRECT on the EQMOD Project website shows you which pins have the 12V on them.

Chris.

[Reggie]

Hi Chris, funnily enough, I checked the other day and didn't spot it, heaven knows why, I've just come from there to this thread and managed to spot it but thanks for the information. Just out of interest, do you know whether the serial on the motor boards for the HEQ5 pro are 3.3v tolerant on the RX pin? I know I'll have to do some level conversion from the 5v from the mounts TX pin to 3.3v for my BT adapter's RX pin. I've got a little level convertor board here but not much point wiring it up if the motor board will take 3.3v as a digital high

Regards,

Reggie.

[chrisshillito]

Hi Reggie,

I'd stick to 5V signal levels if I were you. The Rx line goes directly to the PIC port pin and it is expecting 5V logic. Electrically it may work with a 3.3V high but you are seriously compromising the noise immunity which combined with a comms protocol with absolutely no error correction/detection isn't the best design stategy.

Chris.

[JamesF]

I appreciate that you still need some power supply to the scope which means running at least one cable, plus I'm still running a USB to control my camera and guiding setup. Still working on that!

Power over wifi. It's the only way forward

James

[Reggie]

Hi Reggie,

I'd stick to 5V signal levels if I were you. The Rx line goes directly to the PIC port pin and it is expecting 5V logic. Electrically it may work with a 3.3V high but you are seriously compromising the noise immunity which combined with a comms protocol with absolutely no error correction/detection isn't the best design stategy.

Chris.

The units I have are 1.8-3.3v, so I'll have to use the level convertor Chris

[Gina]

I expect the logic is CMOS rather than TTL (which is decidedly "old hat") and that generally uses 0 and 5v as the logic levels with the threshold at 2.5v. TTL was 0 and 3.3v with around 1.5v as the changeover. Give it what it expects and it'll be happy

[Reggie]

I read the datasheet for the chip on the handset, it appears to be TTL, although the datasheet was a little bit beyond what I'm used to looking at (QFP chips are insane and nothing like atmega 168 chips!!) and the operating voltage for the mcu was something like 1.8v to 5.5v. Logic high was > 2v, or a fraction of vdd, that's where my knowledge fell down

[chrismills]

From a more empirical point of view, I tried a 3.3v BT module and couldn't get it to work. Worked like a dream with a 5v module.

Chris

[Reggie]

I worked it out some more, according to the datasheet, the TX/RXpins are ST (schmitt trigger) and as such the logic high is apparently 0.8x VDD, so assuming voltage is 5v that would make 4v the minimum for a digital high.

I've got a couple of things I can try to bump the 3.3v to 5v, an octal buffer and a logic level converter, I'll let you all know how I get on.

[jnp]

Interesting thread! I bought one of these on a whim in January but it has been sitting on the back burner ever since. I was surposed how tiny the board was, soldering will be a challenge.

Did I buy the right device for being able to control lots of IO pins (for Guiding, electric focuser etc) over a bluetooth connection ? I am hoping that it should be fairly quick to get it up and running?

John

[Reggie]

Jnp, it's debatable whether it's going to be useful for multiple IO, the best you'll get out of it right now is RX/TX so simple serial is it, although there has been chatter on the net about being able to put other firmwares into these units that do allow access to more pins, such as rts/cts/dtr. That having been said, it will control an electronic focuser via serial and guiding via a mount (ascom serial not via the st4 port) and not at the same time through a single device/usb bluetooth dongle pairing.

That's the other issue I see with bluetooth right now, there isn't a cheap bluetooth hub solution available on the market, so you're going to run out of usb ports pretty quickly to get everything going via bluetooth.

[Reggie]

I've been doing some more research, I was wrong and it appears that you can connect at least 2 bluetooth serial devices at the same time to a bluetooth dongle (at least my little belkin), not sure if it will do more or not, I don't happen to have another bluetooth device knocking around that does serial, so not sure how many connections you can have and it doesn't appear to be that stable.

[Reggie]

Chris, Can you give details of your bluetooth setup too? Which bluetooth dongle are you using? Which bluetooth stack is it using? How stable are your connections?