Shop OBEX P1 Docs P2 Docs Learn Events
Stuck: STAMP and ESC? — Parallax Forums

Stuck: STAMP and ESC?

AerostuckAerostuck Posts: 2
edited 2007-11-06 03:07 in BASIC Stamp
I'm completely new to STAMP and am very unsure of where to start. I have an 20-Amp Sensorless Brushless ESC and would like to connect it to STAMP but because I have never seen anything like STAMP before I have no idea where to start. I've looked at the manual but am still clueless about the circuitry. Can anyone help? Thanks!

Comments

  • FranklinFranklin Posts: 4,747
    edited 2007-11-06 02:33
    Sure, could you post the specs on the esc? Most ESCs need a pulse of 1 to 2 ms every 20 ms to operate.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Stephen
  • Mike GreenMike Green Posts: 23,101
    edited 2007-11-06 02:37
    You have to start with the ESC and what it requires.

    A Stamp can generate pulses and streams of pulses of varying width and frequency in roughly the audio range. It can count pulses. It can measure pulse width. It can transmit and receive standard asynchronous serial data at various speeds. It can shift data into or out of external shift registers. It can control analog to digital and digital to analog converters and do some very simple, slow conversion itself (like measure its own battery voltage or generate a fixed or slowly changing voltage). It can interface to a variety of sensors and external devices like real time clocks and memory chips (for data storage like logging).

    It's also a control computer and can manage all sorts of complex control tasks. It has its limits (in terms of speed and simultaneous functions), but it's also easy to use and very very well supported with lots of examples and educational material available for free.

    If indeed your ESC requires a periodic pulse as Franklin described, then your ESC works just like a standard hobby servo and all of the examples and discussion you'd find in "Robotics with the BoeBot" would apply.· You can download that tutorial from the "Stamps in Class" tutorials page you can find from the main Parallax page under Downloads.


    Post Edited (Mike Green) : 11/6/2007 2:42:56 AM GMT
  • AerostuckAerostuck Posts: 2
    edited 2007-11-06 02:41
    Sure. I just lifted this off the website [noparse]:)[/noparse]

    Specs
    Brake: Yes, programmable
    Continuous Maximum Current: 20A
    Input Voltage: 7.2V-14.4V Ni-Cd/Ni-MH; 7.4V - 11.1V Li-Po
    Dimensions (WxLxH): 36mm (1.4 in) x 24mm (.95 in) x 9mm (.37 in)
    BEC Voltage: Dual BEC circuits
    Auto Cutoff: Programmable

    It's an Eflite 20-Amp Brushless ESC with dual BEC

    Thanks!
  • allanlane5allanlane5 Posts: 3,815
    edited 2007-11-06 03:07
    The BS2 controls a "servo" with a 1 to 2 mSec width pulse (generated with PULSOUT) repeated every 20 to 50 mSec. This is the "Servo" control signal.

    Now, an "ESC" is an "Electronic Speed Control". Typically, these accept the "Servo" control signal -- where I assume 1 mSec is full reverse, 1.5 mSec is 'stop', and 2 mSec is full speed forward. You'll have to find the specs for the ESC on it's website to confirm this.

    Now, to control a 'servo', the BS2 has to have a 'common ground' with the servo -- but the power lead can (and should) come directly from the battery. Then, you can connect the 'signal' pin directly from a BS2 I/O pin to the 'signal' pin of the ESC -- once you find that signal.

    Here's the "Manual" -- http://www.horizonhobby.com/ProdInfo/Files/20A-Brushless.pdf

    The BS2 (on the BOE board) has the three-pin "Servo" connector -- ground, Signal, and +5.· The big red wire on the ESC goes to your + Battery voltage, while the big black wire goes to the - battery voltage.· The BOE can be powered by a 9-volt battery -- but you may need to disconnect the +5 volt wire on the 3-pin servo connector.

    Having looked at the "manual" page, it looks like 1 mSec is minimum throttle, while 2 mSec is max throttle, and there IS no 'reverse'.

    Post Edited (allanlane5) : 11/6/2007 3:18:22 AM GMT
Sign In or Register to comment.