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Interfacing PIC to BSII — Parallax Forums

Interfacing PIC to BSII

ArchiverArchiver Posts: 46,084
edited 2001-07-19 19:07 in General Discussion
Honestly I'm a total newbie, but I do know this much:

First of all, the most popular PIC seems to be the PIC16c/f84
As far as I know, you need a PIC programming board, as well as a
PICBaisc compiler. In total these two items cost about $150. I
thought maybe you could just buy another Basic Stamp and have one
send commands to the other. If you got a BS2E or BS2SX (I have the
SX model, nice and fast!) you could have the e/sx as the main
processor, and the regular BS2 as the "slave processor" for doing
input/output information. I plan to eventually do something similar
to this when I can afford to, although I don't have an excess of
commands.

--- In basicstamps@y..., jamesfit@p... wrote:
> Hi all,
>
> I am in the process of trying to fit encoders to my robot. It is
currently
> controlled by a Basic Stamp II processor. I was intending to do all
> processing with the BSII, but on thinking about software for the new
> encoders I have struck a few problems.
>
> I realized that after sending an update signal to the servos every
20ms,
> and
> sampling the encoders for both servos, I was going to have
practically no
> time left to do anything else. I now think I have come up with a
better
> design.
>
> I am going to use a PIC (or some other processor) to both drive the
servos
> and also sample the encoders. I hope to even implement some PID
control in
> there. The question I have is how do I interface the PIC and Stamp?
If I
> have a function in my PIC
> drive_forward( ) how do I call this from my Stamp? I am planning to
use C
> to
> program the PIC.
>
> I am also totally new to PIC's and so have no idea what sort of PIC
I
> need.
> I assume I need a PIC with at least 2 PWM channels built in to
control my
> two motors... is this correct?
>
> Thanks so much for any help you can provide,
> best regards,
> James Fitzsimons

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-07-19 07:33
    Hi all,

    I am in the process of trying to fit encoders to my robot. It is currently
    controlled by a Basic Stamp II processor. I was intending to do all
    processing with the BSII, but on thinking about software for the new
    encoders I have struck a few problems.

    I realized that after sending an update signal to the servos every 20ms,
    and
    sampling the encoders for both servos, I was going to have practically no
    time left to do anything else. I now think I have come up with a better
    design.

    I am going to use a PIC (or some other processor) to both drive the servos
    and also sample the encoders. I hope to even implement some PID control in
    there. The question I have is how do I interface the PIC and Stamp? If I
    have a function in my PIC
    drive_forward( ) how do I call this from my Stamp? I am planning to use C
    to
    program the PIC.

    I am also totally new to PIC's and so have no idea what sort of PIC I
    need.
    I assume I need a PIC with at least 2 PWM channels built in to control my
    two motors... is this correct?

    Thanks so much for any help you can provide,
    best regards,
    James Fitzsimons
  • ArchiverArchiver Posts: 46,084
    edited 2001-07-19 17:49
    > the most popular PIC seems to be the PIC16c/f84
    >

    This has changed the PIC16F876 and the new PIC16F628 give you more for
    your money and they can be programed with simpler programers or by
    getting chips programmed with a boot loader you just need a serial
    cable. If what you are building is a one off then a stamp is the
    cheaper and simpler route but if you need 10 then the cost of a Basic
    compiler and programmer is easily justified. Basic Micro has a very good
    line of products for Pic Micros their web page is at
    http://www.basicmicro.com/

    Craig
  • ArchiverArchiver Posts: 46,084
    edited 2001-07-19 19:07
    James,

    If you could use steppers instead of servos, they are less software
    intensive. I first used a BS-I interfaced to two ULN2003A drivers to drive
    two steppers simultaneously. When I needed more functional control, I
    swapped the BS-I for a 16C622 PIC, programmed with the CCS C compiler.

    Dennis

    Original Message
    From: jamesfit@p... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=UW7vSK8Fvgxt8xwLlXc3FUQ0MAwZdRkVqvvaoaimCPiYWKELo-csIYcNF7w3y5AGMvJ-cUoQVpKQfVReETu16Q]jamesfit@p...[/url
    Sent: Wednesday, July 18, 2001 4:34 PM
    To: SeattleRobotics@yahoogroups.com; basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Interfacing PIC to BSII


    Hi all,

    I am in the process of trying to fit encoders to my robot. It is currently
    controlled by a Basic Stamp II processor. I was intending to do all
    processing with the BSII, but on thinking about software for the new
    encoders I have struck a few problems.

    I realized that after sending an update signal to the servos every 20ms,
    and
    sampling the encoders for both servos, I was going to have practically no
    time left to do anything else. I now think I have come up with a better
    design.

    I am going to use a PIC (or some other processor) to both drive the servos
    and also sample the encoders. I hope to even implement some PID control in
    there. The question I have is how do I interface the PIC and Stamp? If I
    have a function in my PIC
    drive_forward( ) how do I call this from my Stamp? I am planning to use C
    to
    program the PIC.

    I am also totally new to PIC's and so have no idea what sort of PIC I
    need.
    I assume I need a PIC with at least 2 PWM channels built in to control my
    two motors... is this correct?

    Thanks so much for any help you can provide,
    best regards,
    James Fitzsimons





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