I have a potential application for a device like the BBB but it needs a few changes. I’m a software guy so I don’t know if they are minor design changes or major. I work as an OEM in the manufacturing world. Most devices I deal with are 24v. So how difficult would it be do redesign the BBB to have the following:
- 24v power source
- 24v I/O
- 1 to 2gb RAM
I assume a nice cape could also be designed to bring the I/O into nice screw terminals too.
I understand the BBB was not intended for this but it seems a pretty good starting point and I just wanted to know the feasability and potential cost of doing something like this.
Mark
The BBB is not going to be redesigned.
But, you may find someone to do a custom board or you.
- 24V power source, just convert it to 5V.
- That can be done, but it will be very expensive.
- It is already 512MB, not sure why you want to do down 2gb, If I assume that you mean 2GB, it can’t be done. Max memory on the processor is 1GB.
Oh, and the board will not cost $45. It will be a lot more.
Gerald
Deriving the regulated 5 VDC supply from 24 VDC can be a simple as a single pass-regulator with a couple of capacitors. Or you can make it more efficient by using a little switching-regulator chip. 0-24 volt DC inputs just take a resistor divider (two resistors) to scale the input range down to 0-1.8 VDC. That would work for both GPIOs and ADCs. For 24 volt high-side output I would use an opto-isolator (AKA solid state relay) for each output. You drive a transistor (like a 2N2222) with a couple of milliamps from a GPIO pin, and that drives the opto-isolator’s LED with the required 10-20 ma (too much for a BBB GPIO).
All of those could go on a cape, but if you need more than a few of those 24 volt outputs then you might run out of room. Adding more RAM is going to take a custom main board redesign because the processor’s DRAM interface signals are not present on the P8 and P9 connectors.
Gerald, I wasn’t thinking the BBB would be redesigned by you for general consumption. I was thinking along the lines of having someone create a custom version. 2GB is what I meant. Considering the cost of PC’s, software and IO we currently use, a redesigned BBB has to be a lot cheaper. I’m thinking of using the PRU’s for the small portion of our code that has to be deterministic.
Thanks for your input.
Guy,
That’s some very useful information. If I made a cape I would make it large enough to hold the extra circuitry. It doesn’t have to be the footprint of the BBB.
This definitely warrants more investigation.
Mark
Redesigned board will be a lot more expensive. Unless of course you are building and ordering parts in blocks of 100,000 units.
Also, 2gb DDR3 does not exist. You may be able to do SDRAM, but again quantity is the key to all of this.
A cape, that may be the way to go.
Gerald
Mark,
I work in the 24V world also and am working on hardware IO for for a field bus controller.
Email me and let’s see if we can do something - sales@dsgep.com
- 24v power source
Simplest to do: buy 24/5V DC/DC converter. Simplification: look for those which have 5V output and at very least 5W power, better 10W - input voltage frequenty is acceptable in very broad area.
Example:
http://de.farnell.com/tdk-lambda/cc-10-2405sf-e/dc-dc-wandler-24v-i-p-5v-o-p-10w/dp/1996033
- 24v I/O
if You need open-collector outputs ULN2003 is the cheapest and affordable way to go.
Inputs: advised to use simple opto-coupler design (if You plan to use 24V logic I see the ground lying in industrial automation - galvanic isolation in IO is mostly
a must)
In push-pull is needed “poor’s man” solution for small number of outputs is to use 32Vcc R-R input OpAmps - 24V supply + clamp in input not to burn 3v3 output from MPU, but also better is to use opto-decoupled 24V section from 3v3 section for IO in end-point rail and 3v3.
Please read about industry automation electronics before You start such a desing. In a kind of environment i work (Wind Turbines industry) such inputs & output have to be very carefully designed not to destroy the input or output circuitry every several months.
- 1 to 2gb RAM
If you need such amount of ram I advise use Wandboard Quads for application and BBB for IO with communication between those two.
But first I would suggest running Your app in BBB, because 512 MB of RAM is pretty sufficient for embedded application even doing data processing.
regards,
T.
W dniu czwartek, 20 lutego 2014 22:26:04 UTC+1 użytkownik Guy Grotke napisał:
Deriving the regulated 5 VDC supply from 24 VDC can be a simple as a single pass-regulator with a couple of capacitors.
Have You mentioned the 40 Watts colling radiator and according power lost in such a solution?