Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: obiwanjacobi on May 10, 2013, 04:00:28 AM
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I am building my first robot and its going great. It is a robot car kit (https://iprototype.nl/products/robotics/platforms/robot-a4wd)with 4 cheap motors, a dual channel motor driver, an Arduino and a Ultrasonic sensor. I have the motors running and the wheel decoders are pulsing. I am now looking into interfacing with the sensor.
This sensor (http://www.dfrobot.com/wiki/index.php?title=URM37_V3.2_Ultrasonic_Sensor_(SKU:SEN0001)) emits a pulse train when you request a measurement. The length of the pulse train corresponds to the distance of the detected object. The max pulse train length is 50 milliseconds.
I could write an ISR in the arduino that reads this pulse train and do it all in software. I could also add some hardware to unload this boring task from my Arduino.
I have looked into counter IC's. But I would like something that counts the pulses and can be interface with some sort of bus standard (I2C/SPI/CAN - as simple as possible). I have not found a chip that can do that yet. A simple circuit is also fine - doesn't have to be all in one chip.
Anybody has some suggestions?
Thanx.
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The counter IC SN74LV8154N (http://www.ti.com/lit/ds/symlink/sn74lv8154.pdf) has two 16-bit counters (you can stack them if wanted) and a single 8-bit output port , requiring only one shift register like 74HC589 (http://www.onsemi.com/pub_link/Collateral/MC74HC589A-D.PDF) to read as serial with SPI, you need 3 pins for it and 4 pins to control the counter mux. Through-hole or SMT are both available.
You could of course use a small processor like the ATtiny85 as a counter and get the data via SPI.
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Ooh! That's a nice one! Thanx! Excellent < 1 dollar solution. :P
Yes, I am also considering using ATtiny's (or similar) but I am just beginning with robotics and want to start of simple and want to build up to autonomous modules that talk to each other on a bus.
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My suggestion is also to go with a Tiny85. It can talk SPI or I2C and it can count pulses and it can run with zero supporting circuitry (although a de-coupling capacitor doesn't hurt.)
Edit: I looked at the sensor specs, and that sensor has a TTL UART. Just speak serial to it!
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Edit: I looked at the sensor specs, and that sensor has a TTL UART. Just speak serial to it!
:-[ Oops
::) RTFM
I just looked at the sample code for mode 3...
Sorry, to waste your time guys. My bad.
Anyway, good to hear support for using ATtiny's... ;D