I was having a power issue and when I run anything through the on-board voltage regulator (on a linksprite redback), either filtered 5v using a voltage regulator and capacitors before connecting to the redback, or 7.4v unregulated connected directly to the redback it is knocking the power to the 5v output pin to ~3.03v. The range finders I am running are based on a 5v set up.
When I run the board through the USB cable I have no problem with the sensors.
Can I put regulated 5v power on the USB VCC input pin and ground on the USB header?
Would doing this solve my problem as well?
I tested voltages with the USB cable connected and it is doing just over 4.6v, would connecting 5.02v be a problem?
I haven't tried simply because I already burnt out a ~$60 board and had to replace it with ~$80 and I don't want to have to spend more money on credit to finish this project HAHA!
This is a picture, the redback is a copy of the asynclabs yellowjacket. I can see the lines from the VCC go to the 5v output pin, but it also goes to the ttl converter, would that create a problem? http://asynclabs.com/wiki/images/8/8c/YellowJacketv1.JPG
I'm afraid I can't tell from this post what you actually did do.
First off, test it with no loads connected, and see if you get the correct voltage levels.
Secondly, check that your power supplies have enough current capability to power all the loads.
Thirdly, you can apply > 7 VDC to either the coaxial Power Jack, or to the Vin pin on the
Power header, but a statement like "7.4v unregulated connected directly to the redback" isn't
specific enough to tell where you actually connected it.
Fourthly, some people claim it's ok to connect a regulated 5V source directly to the 5V pin on the
Power header, but it may blow the 5V v.reg on the board - and who knows what they use on the
Spider for a v.reg.
The redback input power pin is called RAW and it is connected directly to an onboard 5v voltage regulator and from there to the 5v output pin. When I connect a 7.4v battery to the RAW pin the 5v output pin on the redback is only putting out 3.2v.
I wired together a 5v voltage regulator with capacitors to filter the output so it stays at a steady 5.02v. When I put this into the RAW input pin the 5v output pin on the redback is only doing 3.2v.
In every scenario the 3v output pin is pushing 3v.
My understanding of the architecture of the redback is that the onboard 3v voltage regulator is put in line between the 5v regulator and the 3v output pin. However the power levels I am reading on the 5v output would seem to suggest that there is an issue with the setup on the redback.
When I run the redback from the FTDI USB cable that has the 6 USB header pins the 5v output pin pushes 4.6v which is what the power readings show when I measure the VCC and ground on the USB header while I have it plugged into my laptop. Since the VCC pin is wired to the 5v output I thought I would ask if I am going to burn anything by wiring my regulated 5v supply to the VCC pin. The VCC pin is also connected to the TTL parts on the board, for serial communication. If I only wire 5v to vcc and ground on the same header I would think everything should be fine. I'm basically looking for somebody with more knowledge than myself to affirm this guess if it's possible.
Postholes:
I was having a power issue and when I run anything through the on-board voltage regulator (on a linksprite redback), either filtered 5v using a voltage regulator and capacitors before connecting to the redback, or 7.4v unregulated connected directly to the redback it is knocking the power to the 5v output pin to ~3.03v. The range finders I am running are based on a 5v set up.
When I run the board through the USB cable I have no problem with the sensors.
Can I put regulated 5v power on the USB VCC input pin and ground on the USB header?
Would doing this solve my problem as well?
I tested voltages with the USB cable connected and it is doing just over 4.6v, would connecting 5.02v be a problem?
I haven't tried simply because I already burnt out a ~$60 board and had to replace it with ~$80 and I don't want to have to spend more money on credit to finish this project HAHA!
This is a picture, the redback is a copy of the asynclabs yellowjacket. I can see the lines from the VCC go to the 5v output pin, but it also goes to the ttl converter, would that create a problem? http://asynclabs.com/wiki/images/8/8c/YellowJacketv1.JPG
Thanks for any help,
Postholes
Well the CuteDigi site appears to have no technical specs at all. Wiki is empty. From the photo I'd suspect the regulator
on the board won't be able to supply as much as 500mA (the typical USB current rating). What are the sensors loading
the 5V rail (ie link to datasheet, as always)? Have you checked how much current they need worst case? Can you
provide a separate 5V regulator for them?
to power them?
The jpeg image has what appears to be the top traces only, and it's unclear where the RAW
pin connects to. However, the 5V normally comes from the Vcc pin on the FTDI cable, and this
feeds to the smt 3.3V v.reg. You should be able to connect regulated 5V to the Vcc pin ok and
power the board.
I would have to know what RAW connects to before knowing what to do with that pin.
As the 328 appears to run at 3.3V, you cannot directly interface it to sensors/etc that run at 5V.
I plugged the regulated 5v supply into the vcc pin and ground to the vcc ground, the redback isn't working anymore. So apparently that won't do the trick for me. I'm getting lights but it's not doing anything program wise, it's not starting the WiFi and no print statements are running through the initial setup function over the serial port.
I have to present this project on Tuesday so I think if I order a next day air today would it show up Monday (just guesstimates or do I have to wait till Tuesday at 4pm (when UPS normally comes through my area) if I order next day air on Sunday afternoon. Not that it matters much if the power problem is something I'm doing wrong and wasn't the board then I will still have the same problem with a new one....
I'm pretty sure it's the WiFi module that's cooked on this board, everything runs until I try to initialize and run anything through the WiFi module. It was working before I tried the vcc power and immediately after it stopped so just by process of elimination....
Anyhow suggestions on how to save this thing possibly?
The Maxsonars run at 3.3 or 5V, but they probably have a large current draw when pulsing the
transducers. You may have cooked the tiny 3.3V smt v.reg on the pcb. If that's the case, you
could unsolder it, and solder in anything for a replacement, like a TO-92 part, or even an
LM1117-3.3 on a couple of wires.
The 328 itself will no doubt run at 5V, but doubtful the wifi module will run at that voltage.
You may have accidentally applied 5V or 7.4V to the 3.3V buss sometime in the past, and
cooked either the v.reg or the wifi chip, or both.
If you figure the board is basically toast, you might try replacing the v.reg as in the first
paragraph.
I talked to linksprite tech support about my problems and they tested the boards that they had in stock. They said that the silk screen has a print error and there is no 5v output on the RedBack, only 3v. However when using the FTDI breakout to power the board it does do 5v output.
Hopefully posting this here will help others that might be using this board. When my replacement shows up I will test the output voltages on both the 3 and 5v output pins using the RAW input power pin and the FTDI power.
@PostHoles
The current draw of our sensors is not enough to damage a component such as the yellowjacket. Our LV-MaxSonar-EZ have a max current draw of ~7.5mA and an average current draw of ~2.1 during operation. The max current draw occurs during the transmit burst of the transducer. Such low current draws are not capable of damaging the component being used to read or control the sensor.
Our MB1010 sensor referenced in your post will operate at 2.5V DC to 5.5VDC.
Have you been able to correct the issue? Please let me know if you have any questions by emailing thomas@maxbotix.com and I will be glad to assist you.
Technical support and sales are subject to
the terms and conditions listed on our
website at http://www.maxbotix.com/ MaxBotix,
MaxSonar,EZ0, EZ1, EZ2, EZ3, EZ4, AE0, AE1,
AE2, AE3, AE4, WR1, WRA1, and WRLA1 are
trademarks of MaxBotix Inc.
Thank you for your information and follow up on this problem. I was able to make the sensors work, I had to recalculate the formulas in my sketch but they are functioning now. I am taking 1 reading every 100 milliseconds and every third read I only use the largest value of the three and take three more readings. This, while slow, gives me good information to go on.
The problem I had was a "misprint" on LinkSprites RedBack board. It only has 3v output, but when you use USB to power it the 5v output pin does output 5v. But powering the board through the regulated RAW pin cuts power down to 3v on all output pins. To solve the issue I attempted to use a 5v regulated power supply and the USB VCC and Ground pins. This blew the board when the spec sheet says that this is supported. I had to order another RedBack board from LinkSprite, not sure what to do about the broken one..
