BOE Rev A - C
mikeslaney
Posts: 17
Hi There,
I have a BOE Rev A w/ a BS2sx chip. I've decided to move the stamp to a larger bread-board but I only have access to the Rev C. shematic.
I imagine that I would be better off wiring the board to match the Rec C. schematic?
The Rev C calls for a 1000uf cap between VDD and ground and VR1 out to ground but does not specify what type (electrolytic, tant, etc) - does it matter?
Also, Rather than risk the possibility of nicking the bottom of the stamp, I "stacked" a couple sockets - one that is "permanently" attached to the stamp to protect the bottom of the stamp and one that is "permanently" on the breadboard. I poorgram the stamp then move the stamp and it's socket to the device that also has a socket of it's own.
Would there be a significant signal loss due to the multiple connections between the stamp and the devices to which it is attached?
Whew! I'd hate read that aloud....
I just started using the stamp after looking at it for about 4 years. Your support, users and parallax inc, has been outstanding. Thank you so much for your help and your positive attitude. Very Cool.
I have a BOE Rev A w/ a BS2sx chip. I've decided to move the stamp to a larger bread-board but I only have access to the Rev C. shematic.
I imagine that I would be better off wiring the board to match the Rec C. schematic?
The Rev C calls for a 1000uf cap between VDD and ground and VR1 out to ground but does not specify what type (electrolytic, tant, etc) - does it matter?
Also, Rather than risk the possibility of nicking the bottom of the stamp, I "stacked" a couple sockets - one that is "permanently" attached to the stamp to protect the bottom of the stamp and one that is "permanently" on the breadboard. I poorgram the stamp then move the stamp and it's socket to the device that also has a socket of it's own.
Would there be a significant signal loss due to the multiple connections between the stamp and the devices to which it is attached?
Whew! I'd hate read that aloud....
I just started using the stamp after looking at it for about 4 years. Your support, users and parallax inc, has been outstanding. Thank you so much for your help and your positive attitude. Very Cool.
Comments
Stacking sockets is a time-honored tradition. Adding the extra height and distance should not be a problem, as long as the mechanical connections are good.
Will I need to put that cap on the target device also? I was planning on using a 5V wallwart right to the stamp but that may not be a good idea(?). The cap just cleans the power a little right? Could I just use a low ripple 5v wallwart or should I still condition the power with a reg and cap. What are the specs for power supply ripple/noise?
If you can recommend better schem/docs for the BS2sx, just ignore the rest and show me the way. So far I haven't been able to find the "explanation" side of the schematic(s)
What about a 7805 as a PS regulator? The Rev C BOE (schem) has one but other documentation I have read warns against using less than 6V.
The schem for the Rev C shows Vin on pin 24 but there is nothing going to it? What is Vin?
Pin 23, VSS, is not connected. Is that the same at the VSS on pin 4?
The schem shows VDD, pin 21, just going through a 1kuf cap to ground but I get V+ when I pin it out on the BOE.
I'm confused about what Vin, VSS, and VDD really are.
In the meantime, I won't be hooking it up to the new breadboard until I get a better understanding.
Thanks,
Mike Slaney
"Unregulated DC" is the most common. It has a transformer and two or four diodes inside. It produces DC with lots of ripple on it. Also, if it is rated 9 volts at 1000 mA, for example, it probably starts out at 12 volts DC with no load. It only goes down to 9 volts with 1000 mA output.
"Regulated DC" has a transformer, diodes, and a regulator inside. It could also be a small switching power supply. These cost a bit more than Unregulated power, but could be used to drive a BS2 without further regulation.
The BS2 requires 'clean' 5 volt DC power on its VDD pin. However, it *has* an on-module regulator, which will take 7.5 to 12 volts unregulated DC without any problems. This lets it take a 9-volt battery without problems, too.
The intended use of the BS2 has you putting 9 volts DC in the 'Vin' pin. The on-module regulator then converts that into 5 volts for the BS2 and puts it out on the VDD pin.
If you want to wire the BS2 directly to an externally regulated power supply, you would connect the +5 volts directly to the VDD pin. This would bypass the on-module regulator. The BOE board has such an external regulator -- that 7805, 3-pin device with the metal back. This lets you use about 1000 mA of current on your projects on the BOE. Since the BS2 takes very little (5 mA?) this is lots of power.
Meanwhile, the BOE also makes available a jumper to VIN. This is the 'raw' unregulated voltage coming from the wall-wart. It can *sometimes* be used for servo's, or relays, where the higher voltage is useful. I prefer using the regulated voltage mostly, myself.