Shop OBEX P1 Docs P2 Docs Learn Events
Second HM55B Compass — Parallax Forums

Second HM55B Compass

spainespaine Posts: 51
edited 2006-08-25 19:19 in General Discussion
I posted a couple weeks ago the HM55B I had worked, and then stopped. I never got a response, so I bought another, and tried it. The new HM55B again never gives a valid ready status, and leaves me again without results.

Before I hooked this module up, I check the wiring twice, and it matches the package insert document. Since the module failed, I also tried the four wire hookup instead of the three, but still no luck.

I used the same code that was provided in the package insert (see attached). The only change I made to the code was to update the directive to read BS2p from BS2. After it failed to provide a reading, I added some debug statements. I can see that this module always has the status of 0000, and I never get a 1100 that I'm need to retrieve the reading.

This is very frustrating. jumpin.gif

What can I check. I mean, are there certain voltages I should see at certain times, at certain test points?

All help is welcome. Thanks!
bs2
bs2
TestHm55bCompass.bs2
3K

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-24 16:04
    spaine -

    Do you have pin 3 of the compass module tied back to the Stamp ground?

    What are you using to power the Stamp, and this module? What is the MEASURED voltage of that/those voltage source(s)?

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
  • spainespaine Posts: 51
    edited 2006-08-24 16:29
    Pin 3 of the compass is tied to ground (Vss).

    The Stamp (and Compass) are on a BS2P24/40 prototype board, which is plugged into the wall. The Compass Pin 6 is tied to Vdd. When I measure Vdd to Vss it comes in at around 4.92 V.

    This was the same way I had the other HM55B setup also. I'm thinking of going out and trying the Devantech compass, but I like to stick with one company if I can.

    Any more thoughts?
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-24 16:54
    spaine -

    Tell you what I'll do. If we (collectively) can't figure out what's wrong I'll BUY BOTH compasses from you! How's that?

    That just shows you how much I believe in Parallax products AND the power of this Stamp Forum. Why am I so sure? Ten years of experience on this Stamp List, should speak volumes!

    Don't jump ship quite yet - PLEASE smile.gif

    Please describe the power supply, and include manufacturer, catalog number, voltage, ampacity, etc if you can. Although 4.92 should be okay under ordinary circumstances, with so littlw load on it, if it's a 5.0 VDC power supply, it's a bit short of "poop" IMHO. A bit more load, and you'll drop below the REQUIRED 4.8 VDC of the HM55-B module.

    Other than the Stamp and the compass module, please describe any other loads on this same power supply.

    Hang in there!

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-24 18:25
    Have you tried a different set of I/O pins?· Perhaps you have damaged pins.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • spainespaine Posts: 51
    edited 2006-08-24 21:15
    Thanks Chris, I have tried a different set of I/O pins, but still no luck. What do you think of Bruce's comments regarding voltage?

    Thanks Bruce, but I won't hold you to the purchase of my two compasses. But I will take all the support you (and whoever else is willing to give me). I am interested in what you mentioned regarding voltages.

    The power adapter is an A/C to D/C 7.5V converter from Radio Shack, I'm not sure what Amp it is rated at, when I get home I can get it.

    At today's runtime I had the HM55B and a SiRF GPS module conected to Stamp's Vdd. I have a 7805 5V regulator at home, I could try giving the HM55B its own power source.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-24 21:51
    I have contacted the author of the demo code you refer to in order to get his opinion, but I am wondering since you're using a BS2p, and this was written for the BS2 if timing could be an issue.· The Enable line is being brought HIGH then LOW immediately, then a SHIFTOUT is being performed.· I don't know without doing more research if the timing could be an issue.· I will connect one up myself today to see if I can get it to work and reply back.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • spainespaine Posts: 51
    edited 2006-08-24 22:17
    I hadn't thought about speed being an issue.

    Thanks, if you find out anything, please let me know.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-24 22:36
    Okay,

    ·· Speed isn't an issue...First I connected a BS2 to test things...Oddly it didn't work...I re-check of my wiring showed that I had pin 5 on the compass to P5 and pin 4 to P4.· that's backward and I couldn't figure how I did it, but for some reason a quick glance at the quick connect diagram played a trick on my eyes.· Once I reversed those connections it came alive.· I then switched in the BS2p and re-ran the code.· It works.· So timing is not an issue...This is on a module I went and pulled right from stock.· I would triple-check your wiring.· If I can make a mistake...

    Take care.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • spainespaine Posts: 51
    edited 2006-08-24 23:30
    I will triple check it when I get home this evening. Thanks!
  • spainespaine Posts: 51
    edited 2006-08-25 03:46
    Chris and Bruce, thanks for all the help.

    I did have it wired correctly, but I did have some bad pins. I don't know what I could have done to destroy 9 pins, but I only have 7 I/O pins that currently work.

    Chris, is it easy to lose a pin, or could I possibly just have a bad chip?

    Again thanks for the help.
    Stephen
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-25 06:39
    Stephen -

    It's REAL EASY to blow out pins if you DON'T use protection resistors whenever you hook the pins to external devices. The protection resistors limit the amount of CURRENT that can exist in any circuit to which it's connected. Thus, even f you overload a pin, the Stamp pin ports won't be harmed. The other thing that will kill pins and the entire Stamp itself, is static discharge. This is NOT unique to Stamps, but any CMOS electronic device. This is why static straps are often used when handling any CMOS device, or any chip for that matter.

    Inre voltage - you realize you can't power the HM55-B from that power supply directly? The published voltage limits are: 4.8 ==> 5.2 VDC. Please beware of any voltage limits your GPS may have as well.

    Next step - ampacity of the power adapter, or the Radio Shack Catalog Number from which we can determine the ampacity.

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
  • steve_bsteve_b Posts: 1,563
    edited 2006-08-25 12:55
    spaine,

    What version of the BS2p were you using? the 40pin version?
    The BS2P40 has a 2 sets of I/O pins. The first 16 are addressed normally (like with the BS2) but the 2nd set are addressed differently (using the AUXIO command).

    CAn you clarify?!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-25 15:09
    All BASIC Stamp Modules are fully tested before shipping.· I always recommend clearing previous programs before connecting circuitry to any BASIC Stamp Module.· The reason is you may have had a program that made several pins outputs.· Not you stop using that circuit and connect a new one which these pins will be inputs.· When you power up the Stamp Module to download your new code the Stamp pins are doing what the last code told them to do.· Since they're outputs, now connected to outputs, you have a problem.· And without the resistors Bruce mentioned it could damage the pins.· On the other hand it could be something simple...Which board are you using with which Stamp Model?· If you have a BS2p24/40 demo board and a BS2p24 Module then you cannot access the P8 through P15 from the main header.· They appear on the AUX header.· This is similar on the PDB with regards to 40 pin modules.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • spainespaine Posts: 51
    edited 2006-08-25 17:01
    Again, thanks to everyone. Bruce, I should have trusted you, as it does seem like Parallax is worth it. Chris thanks for the tech support.

    I am using a BS2P24 along with the BS2p24/40 demo board, which now leads me to believe that pins 8-15 work (or at least I will have to recheck). I had been trying to access P8-P15 via the main header. I will try the AUX header when I get home this evening.

    Bruce, thanks for mentioning possible static dammage, but I have an ESD strap and I wear it. With regards to Protection resistors, what should the resistance be? Or, will resistance be dependent upon the circuit?

    Thanks again,
    Stephen
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-25 17:32
    Stephen,

    ·· That's it!· The P8 through P15 are not on the main header, as these are for the BS2p40 main P8 through P15.· You will need AUX P8 through AUX P15 on a BS2p24 to get those pins to work.· Take care.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-25 18:12
    Stephen -

    Glad you've got it sorted out. It seemed like it should be something fairly simple that was being overlooked. You'll not have that happen again anytme soon I'm sure.

    Next time you're buying passives, just grab a handful of low wattage 220 ohm resistors for protection use, and you should be fine. If you get involved with motors, relays or solenoids, also grab a few low voltage (say) 500 mA-1A diodes to use for fly-back protection as well. Small diodes and low wattage resistors are cheap enough to let the magic blue smoke out every once in a while, in lieu of having the Stamp pins do it smile.gif

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
  • spainespaine Posts: 51
    edited 2006-08-25 18:53
    Bruce said...

    Inre voltage - you realize you can't power the HM55-B from that power supply directly? The published voltage limits are: 4.8 ==> 5.2 VDC. Please beware of any voltage limits your GPS may have as well.

    I didn't quite understand your comment regarding the voltage. I was under the impression that if I hooked 9VDC to a 7805 regulator to get 5 VDC, that I could then use that to power HM55-B (or anything else that could use 5 VDC). Was I mistaken as to what you were trying to tell me?

    Thanks,
    Stephen
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-25 19:19
    Stephen -

    I TRY to be as clear as I can be when I write, so let's please review what I said:

    "Inre voltage - you realize you can't power the HM55-B from that power supply directly?"

    Please note the word DIRECTLY. If you are using a 7805 after the wall wart, then your're NOT using the wall wart DIRECTLY - right?smile.gif

    OTOH, perhaps I should have SAID wall wart rather than the less specfic "power supply", or said "packaged power supply" meaning the wall wart. Wall wart is such an UGLY word smile.gif

    Regards,

    Bruce Bates

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    <!--StartFragment -->
Sign In or Register to comment.