HEQ5/6 Bluetooth adaptor project

[oshb5]

Hi All

Well iv just got finished with the latest project on the HEQ5 I have I was sick of the cables so started to look into bluetooth alternative. EQMod already has the facility to control over serial and there is already a circuit mod but again it is cable operated so I looked into the wireless mod that is for sale out there And for the mount end and pc dongle it is £60 and quite large, That was enough for me I did not look any further as I had seen various messages on the subject on other forums. So I started my own search. I looked for a small Bluetooth module I had seen on a certain site The only mistake I made was thinking I had ordered a serial module which in therey I had Anyway read on. I then built the EQDirect Max232 circuit that is shown in the EQMod pages. I also ordered a small Bluetooth dongle one of the smallest you can get at less than £3 from the far east of course. All the things where assembled and the BT dongle installed in the PC and ran with the drivers attached to the OS No extra s/w needed. The DB9 serial plug was replaced in the max232 cuircuit by the Bt module taking care to make sure tx went to TX and so on. The module needed 5v which is the same as the max232 chip needs s i just ran a extra lead from the 7805 ic to power the BT module. This all came together fine. but for some reason it would not work. I thought it may be the TX and Rx reversed. But even with these changed over it still would not work.. On running EQMod the BT went on line for a few seconds and then i got the message could not connect. This was 2 weeks ago. So I thought I had made the max 232 circuit wrongly I replaced the BT module with the DB9 socket and plugged in a serial cable and that worked. this is when the head scratching started. I took to the various forums and not just for astronomy. I found one in a robotics forum that was having a similar problem. and that was that the output from the BT module was actually TTL and not serial Well it was serial TTL. This being so the mount is also TTL so got to wondering if it was just this BT module that was needed to be attached directly to the mount. So thought i would give it a go So i built up a circuit on breadboard and still used the 7805 for the voltage to power the BT module but now has ordered a proper dc-dc power reducer . Anyway as soon as it was all put together and powered up it worked like a dream. and has about 30' of range which i feel is plenty. So i will get it all put into a nice neat box and get some photos. But i would say for all parts needed including the BT dongle it will end up being less than £20 complete.. When I get the photo and put it up on here. I will also put up a list of parts and part No's with the prices..

Regs Andy

[red dwalf]

sounds interesting Andy, look forward to it

[Reggie]

Nice work Andy, Sounds like a project I was going to do about a year ago, got all the parts but didn't have the impetus to finish it.

Do you have a link to the BT dongle that you use? I've used these boards from e-go china and these boards from seeedstudio, both have an smt pitch on the boards, so you either need to etch your own carrier board or you can buy them like this from e-go or you can just use kynar to solder to something bigger.

I prefer the £9 for 2 boards in the first link, they run off 3.3v so logic levels need converting. There are quite a few different modules like this one using the csr bc417 chipset, I was hoping to find one with a firmware that allowed us to use rts/dtr to control long exposure, I think I may have found a way to turn it on though, I'll let people know if I find out.,

[oshb5]

Hi

Yep I sorted the level problem out with a piggy back breakout board which set the TTL logic levels right for connecting direct to the mount via the RJ45. Its the same with the USB-TTl to RJ45 if you buy the 3.3 version of the USB-TTL convertor it wont work. So once I got it soldered to the breakout board it was fine. And as you say the £9 for 2 is a good deal but the breakouts are about £3.50 then you have to position and solder But now I can get them as a 5v set already soldered at £7.50. which is the better deal. and no messing with the minute soldering LOL.

Plus the two serial mount adaptor units I had already built for the project in the first place are now no longer needed so think I will put them in project boxes and sell them on the buy sell forum..

Regs Andy

P.S. Photos on their way but now iv altered the circuits I can get them in a even smaller project box which is winging its way to me as i speak.

[Starjumper]

Sounds great looking forward to seeing the details, well done Andy.

John

[MG1]

looking forward to seeing how this goes...I learn so much from you guys that actually have a clue what you're doing!

Thanks for sharing

Michael

[Reggie]

Hi Andy, I etched my own breakout boards, no components but all the pins are available on 0.1" pin headers You're right of course, the pin pitch on the dongles is a bit on the small side but if you use 'kynar' wire and a jewellers loupe it's very thin stuff so you can get away with not spending money on breakout boards for the bluetooth altogether.

Either way, what you're doing is fantastic, I don't want to sound like I'm criticising anything, just offering ways to save money

[oshb5]

Hi

How did you go about increasing the 3.3v ttl levels to 5v? as they will not work till the right voltage is attained. I had also thought about incorporating the max232 chip into the same box. that way the owner could actually reprogramme the bluetooth module direct over serial That is your own pin and user name as well as having the ability to change to serial cable control of the mount as well as Bluetooth. lets face it nothing worse than 2 or 3 units in close proximity all with the same name and pin code LOL.

As a extra Im also Im looking into being able to have a external optional 6dbi antenna fitted to the BT unit box if needed. My small box has arrived so will get it in today and a photo taken and published.

Regs Andy

[Reggie]

RX on the bluetooth is an input, it requires the level to be dropped to 3.3v via a simple voltage divider. TX on the bluetooth is an output, as long as whatever the TX line is connected to is 3.3v tolerant then it's fine (arduino requires > 2.5v I believe for a logic high signal).