Bus Pirate v4 high voltage interface

Hacking multi-tool. Get one for $30, including worldwide shipping.

Bus Pirate v4 high voltage interface

Postby doozer » Fri Jan 20, 2017 8:29 pm

Hi All,

I have a pool controller that I would like to control. Research thus far (based on chips on the pcb etc) has led me to believe its running a serial interface, possibly RS485.

However, as its designed for long runs its using 33VDC with respect to GND.

I realise I could direct connect to the main CPU, but its a pain to work in or around the pool equipment enclosure.
And if I do eventually make my own interface it will need to be able to send/receive at 33V.

So, my long question is:
Is there some simple circuit I can build that will shift/scale incoming data from 33V down to say 3.3V (or 5V) and do the opposite when sent?

I tried figuring out how the pool controller is doing it, but some of the chips and components are unreadable for manufacturer markings. This may be deliberate, or could simply be because its been out in the elements for many years.

Thanks,
Matt.
doozer
Newbie
Newbie
 
Posts: 2
Joined: Fri Jan 20, 2017 8:09 pm

Re: Bus Pirate v4 high voltage interface

Postby USBEprom » Sat Jan 21, 2017 5:13 am

Hi doozer.
I am not a great expert in that, but I think that could be possible to use something like the MAX485:

http://datasheets.maximintegrated.com/e ... MAX491.pdf

http://www.sunrom.com/p/rs485-ttl-module

http://electronics.stackexchange.com/qu ... y-response

Be seeing you.

U.Sb
USBEprom
Full Member
Full Member
 
Posts: 113
Joined: Wed Mar 14, 2012 4:09 pm

Re: Bus Pirate v4 high voltage interface

Postby doozer » Sat Jan 21, 2017 7:58 pm

USBEprom wrote:Hi doozer.
I am not a great expert in that, but I think that could be possible to use something like the MAX485:

Be seeing you.

U.Sb


Thanks, but the MAX chip seems to expect a line voltage of around 12V.

Looking at the controller PCB, my best guess is its doing some sort of voltage divider on the input and using a transistor to raise the output level from TTL to 33V.
doozer
Newbie
Newbie
 
Posts: 2
Joined: Fri Jan 20, 2017 8:09 pm


Return to Bus Pirate Support

cron