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York Jong

「單」晶片控制多組 PWMs - 160 views

作者: ykjiang (York) 看板: Robotics 標題: Re: 「單」晶片控制多組 PWMs 時間: Wed Dec 13 00:17:04 2006 ※ 引述《happosai (八方齋)》之銘言： > 其實用 FPPA 產生 PWM 訊號一點都不難,因為那一顆CPU就只負責 > 產生PWM訊號，講白一點都是死迴圈，真正 update PWM 是另外一顆 > 負責，所以程...

embedded motor pwm

started by York Jong on 28 May 07 8 follow-ups, last by York Jong on 28 May 07
York Jong

BEAM Pieces -- Integrated circuits - 0 views

library.solarbotics.net/...parts_elect_ic.html

5star beam collection electronics ic motor robot solar survey

shared by York Jong on 27 May 07 - Cached
  • 1381s are CMOS voltage-controlled triggers -- these "gate" a source until the voltage is above some "trip" limit, at which point it is allowed onto a third pin
  • We use them as 3- or 5-volt triggers
  • This chip is often considered the heart of Nv net technology
  • ...22 more annotations...
  • The '240 is often called "the bicore chip," because we can take advantage of the 240's inverters to turn a single 74*240 into a bicore
  • The '240 also has tri-state outputs, so an enable line can be used to turn its outputs on and off simply (good for adding reversing capability to a 'bot).
  • any *cores built with a 74*04 will require additional logic "downstream" to amplify the current to levels sufficient to drive a moto
  • Schmitt triggers can't easily be used in suspended bicore implementations
  • use its buffers as little current amplifiers
  • it is usable for either grounded or suspended bicore designs (but better for suspended)
  • 74HC/HCTxx non-buffers (74HC14 or 74HC04) draw about half of the current consumption, and have about half the drive current compared to HC / HCT buffer chips (74HC240 or 74HC245). Non-buffer chips are thus better for oscillators, say Nv and Nu applications; they are not suited for use in driving motors.
  • 74AC is best suited for motor driver applications with all inputs driven rail to rail.
  • The '245 is an octal buffer chip, and so has 8 channels of buffering power available for our misuse. This chip was designed for data transmission uses, but we'll misuse it as a motor driver chip
  • The '244 provides us with 8 (thus the "octal") buffers, enableable in banks of 4. This is a very useful chip for amplifying small currents
  • it can drive up to 4 motors in 2 directions each, or you can "buddy up" inputs and outputs to drive fewer motors at higher current
  • it can drive up to 4 motors in 2 directions each, or you can "buddy up" inputs and outputs to drive fewer motors at higher current
  • If you can't find 1381s locally, you might have better luck finding its European cousin, the TC-54 -- for details on it
  • Note that if you need more than about 200 mA per motor, you'll need to use an H-bridge, or some similar motor driver
  • The ideal BEAM circuit would use a low (2V-3V) voltage core and sensors combined with level shifting high (5-6V) volt motor drivers to maximize efficiency.
  • 74ACxxx used in typical BEAM applications uses 4x more supply current than does 74HC/HCTxxx.
  • York Jong on 27 May 07
     
    The following material is intended to cover usage and part selection details of ICs you're most likely to see in BEAM robots.
York Jong

BEAM Circuits -- Field sensors - 0 views

www.solarbotics.net/...sensors_field.html

4star beam circuit electrometer sensor

shared by York Jong on 29 May 07 - Cached
  • note that the human body is a good absorber of stray RF fields, so this sensor should be a good people-detector
    • York Jong
      York Jong on 14 Jun 07
       
      should be shield, not sheilduses two of six inverting Schmitt trigger in a 74HC14 IC
York Jong

BEAM Circuits -- 74*24x-based motor drivers compared - 0 views

library.solarbotics.net/...driver_24x_comp.html

3star beam comparison driver electronics ic motor

shared by York Jong on 27 May 07 - Cached
  • In many ways, both the 74*240 and 74*245 are equally handy for BEAM use; both have 20 pins, and so the main difference that most folks will care about is that one inverts drive inputs, while the other doesn't. Out of curiousity, I decided to torture test the two chips to see how they compared under load.
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