Compass AppMod and BS2p
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Posts: 46,084
I searched and see that there are very few posts that discuss the
Parallax Compass AppMod.
I am having some simple issues trying to use this and would love to
hear about anybody else's experiences.
Since I am not using the stackable development boards, I have wired
the Compass AppMod to a BS2p Demo Board. Once I noticed that the
diagram of the header was reversed in the manual that came with the
Compass (I traced the leads from the LM2940CT power regulator to find
Vin's pin and worked from there), I began to doubt the manual. An
e-mail to Support got a response that told me the wrong thing, exactly
what the manual said. I went on my own at this point.
By connecting +7.5vdc to Vin and grounding Vss, the Compass began
working fine in Standalone Mode. The LEDs made sense and I went on to
add the serial line. I connected P12 from the BS2p to the 'P5' line on
the Compass header and pulled it up to Vdd with a 4.7k resistor. I
used inverted modes in SERIN and SEROUT and the Compass seems to be
responding.
The problem I am having is that I cannot get the Compass to accept
'low power mode'. The manual says to send the following command (They
use P5, in my code I use P12 as mentioned above). I've tried this and
various mutations of it. Can anyone else get the Compass to work on a
BS2p, but only with the Compass LEDs turned off?
Also, this solution only seems to work at 4800 baud. If anyone sees
what I've done that prevents this from working in 9600 baud, do tell
me; I'm weak on the electrical half of STAMP life.
Here's the manual's test code for clearing the Compass and moving it
to low-power mode:
SEROUT 5, 188+$8000, [noparse][[/noparse]"!CM0C", %01]
(* I know the baud bits are different for the BS2 and the BS2p, and I
know they are using 5 and I am using 12. I'm seeing correct responses
from the Compass. I am just nto seeing it shut off the LEDs. Any help
out there?)
Parallax Compass AppMod.
I am having some simple issues trying to use this and would love to
hear about anybody else's experiences.
Since I am not using the stackable development boards, I have wired
the Compass AppMod to a BS2p Demo Board. Once I noticed that the
diagram of the header was reversed in the manual that came with the
Compass (I traced the leads from the LM2940CT power regulator to find
Vin's pin and worked from there), I began to doubt the manual. An
e-mail to Support got a response that told me the wrong thing, exactly
what the manual said. I went on my own at this point.
By connecting +7.5vdc to Vin and grounding Vss, the Compass began
working fine in Standalone Mode. The LEDs made sense and I went on to
add the serial line. I connected P12 from the BS2p to the 'P5' line on
the Compass header and pulled it up to Vdd with a 4.7k resistor. I
used inverted modes in SERIN and SEROUT and the Compass seems to be
responding.
The problem I am having is that I cannot get the Compass to accept
'low power mode'. The manual says to send the following command (They
use P5, in my code I use P12 as mentioned above). I've tried this and
various mutations of it. Can anyone else get the Compass to work on a
BS2p, but only with the Compass LEDs turned off?
Also, this solution only seems to work at 4800 baud. If anyone sees
what I've done that prevents this from working in 9600 baud, do tell
me; I'm weak on the electrical half of STAMP life.
Here's the manual's test code for clearing the Compass and moving it
to low-power mode:
SEROUT 5, 188+$8000, [noparse][[/noparse]"!CM0C", %01]
(* I know the baud bits are different for the BS2 and the BS2p, and I
know they are using 5 and I am using 12. I'm seeing correct responses
from the Compass. I am just nto seeing it shut off the LEDs. Any help
out there?)
Comments
Look at page 7 of the AppMod sheets and read the paragraphs from there to
the end. It says that the AppMod is
hard wired to P5 not P12, change the wiring you have to follow what the AppMod
says and everything should work
fine. I noticed that the AppMod is backwards for the Board of Education, which
is used for the BOE-BOT and is
correct for the other boards. I have also read somewhere that the header for
the Board of Education is backwards
from all the rest, but I am not sure where I read this.
Have Fun !!
Dale Fleischmann
hoofit42km wrote:
> I searched and see that there are very few posts that discuss the
> Parallax Compass AppMod.
>
> I am having some simple issues trying to use this and would love to
> hear about anybody else's experiences.
>
> Since I am not using the stackable development boards, I have wired
> the Compass AppMod to a BS2p Demo Board. Once I noticed that the
> diagram of the header was reversed in the manual that came with the
> Compass (I traced the leads from the LM2940CT power regulator to find
> Vin's pin and worked from there), I began to doubt the manual. An
> e-mail to Support got a response that told me the wrong thing, exactly
> what the manual said. I went on my own at this point.
>
> By connecting +7.5vdc to Vin and grounding Vss, the Compass began
> working fine in Standalone Mode. The LEDs made sense and I went on to
> add the serial line. I connected P12 from the BS2p to the 'P5' line on
> the Compass header and pulled it up to Vdd with a 4.7k resistor. I
> used inverted modes in SERIN and SEROUT and the Compass seems to be
> responding.
>
> The problem I am having is that I cannot get the Compass to accept
> 'low power mode'. The manual says to send the following command (They
> use P5, in my code I use P12 as mentioned above). I've tried this and
> various mutations of it. Can anyone else get the Compass to work on a
> BS2p, but only with the Compass LEDs turned off?
>
> Also, this solution only seems to work at 4800 baud. If anyone sees
> what I've done that prevents this from working in 9600 baud, do tell
> me; I'm weak on the electrical half of STAMP life.
>
> Here's the manual's test code for clearing the Compass and moving it
> to low-power mode:
>
> SEROUT 5, 188+$8000, [noparse][[/noparse]"!CM0C", %01]
>
> (* I know the baud bits are different for the BS2 and the BS2p, and I
> know they are using 5 and I am using 12. I'm seeing correct responses
> from the Compass. I am just nto seeing it shut off the LEDs. Any help
> out there?)
>
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> Hi,
>
> Look at page 7 of the AppMod sheets and read the paragraphs from
there to the end. It says that the AppMod is
> hard wired to P5 not P12, change the wiring you have to follow what
the AppMod says and everything should work
> fine.
Yes. As I said, IO is working to the Compass at 4800 baud.
The problem, I repeat, is that low-power mode does not seem to be
working. The PIC state machine seems to have real timing demands.
Since yesterday I have found that if I send the !CMOC command after
*every* read of the Compass, the LEDs stay off except during and after
the CMO? exchange. Sometimes this fails and the LEDs remain on until
the next sampling. So now the LEDs blink now and then, and power
consumption is reduced but not optimal.
I'm wasting lots of time trying "PAUSE n" everywhere, further slowing
down my demo.
Again, can anyone can explain why this works only at one baud rate, or
how to make low-power mode 'stick'?
I'd say right now, a better buy for the money is to buy the Compass
sensor by itself and put it behind a PCF8574. The PIC on the AppMod
seems to have some issues and by driving it yourself, you may find
simpler/faster workarounds.
http://www.imagesco.com/catalog/DigitalCompass/DigitalCompass.html