BS2 + sensors advice asking

TigPT

Hello,

i'm new with BS2, i got one boe-bot and i was trying to improve it, and make some new robots with BS2, and i was looking for some sensors.

i found this http://www.sparkfun.com/commerce/product_info.php?products_id=741 and i'm thinking in buy, but i don't know if i should..

do anyone know this sensor board? it will be easy to interface it with BS2? will be cheaper and better to buy this 2 sensors separately or will be good to buy this "all in one" board?

i will w8 for some coments before buy.. thanks


(well and what ultrasonic rage finders? what shueld i go for something cheap, good and easy to use?)

Franklin

Have you completed all of the exercises in the boebot manual? I would start with the ping))) ultrasonic first and then if you have a need for another sensor get what you need not the other way around. By that I mean don't buy a sensor and then try to think of something to do with it (unless your rich and then in that case buy two and send one to me [noparse]:)[/noparse] )

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- Stephen

TigPT

hello..

yes, i finished all the exercises in the manual.. and that not include ping, because it dues not have a ping sensor.. thats why i need buy one, it was only with some leds, infra red leds, and sensors, speeker, and ldr.

i started making bs2 talk with my java programs by r232.

i was not thinking in buy the ping)) because it use one of my bs2 pins.. in stead of that maybe srf05/08 cause use i2c.

i'm waiting for some advices. thks for all replys.

Franklin

I2C will also require a pin or two so I don't see the advantage there. What I was trying to say is that you need to deceide what you want to do first then find out what you need to accomplish that goal.

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- Stephen

TigPT

ya.. but with i2c i can use that 2 pins for multiple sensors.. (i think.. i dont know a lot about it)

i have an idea about a balanced 2 wheels robot, actually i was thinking in 4 wheels, connected left (front and back) and rigth (front and back) but for be "walking" in 2 wheels only, and that's why i wanna a gyro and a accelerometer.. i think its a requirement.

i was asking if this ones are easy to connect with bs2, and if do.. what do i need to do it.. since they are analog output as i see in datasheet, (it seems to) do i need an analog/digital converter?! what the best/cheap ones for this sensors? whats my alternatives?

shueld i think in invest in SSC-32 to servo controllers or its better buy motor controllers?

thks for your reply Franklin

TigPT

would max1238 from maxim be good to interface this gyro and accelerometers to my bs2?

i wanna them to make a balanced robot...

here is max1238 datasheet:
http://www.ortodoxism.ro/datasheets/maxim/MAX1236-MAX1239.pdf

Tracy Allen

The MAX1238 is a very capable and versatile ADC. I'm sure you are aware (from your previous comments about sharing pins among sensors) that this is an I2C chip. It would be easier to do this if you had a BS2p or BS2pe, which have the I2C commands built in. I am concerned about the speed of operation (for a balancing robot, which might require a snappy response), and also the amount of code space required for the I2C routines. I'm not sure that those would be issues. But the bit-banged I2C routines are relatively slow and take program space. I do have BS2 and BS2pe code for the MAX1238 if you decide to go that route.

ADCs that use SPI or microwire take less code space and work faster with the BS2, but right, they do also take more pins. Sorry, I can't help with anything about the robot design.

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Tracy Allen
www.emesystems.com

TigPT

thanks a lot, it was a really good help.

its true that i2c will be slow.. probably 2 slow for balancing a robot.

i'm considering in get another microcontroler to the balancing process with adc integrated, so i can use analog interfaces directly with it, and let the BS2 for other jobs that not require so much speed, like magneto North location, bluetouth, sonar sensors and servos control.

what do you think about it!? integrating 2 microcontrolers with i2c probably, and use them to work together with different task.

what about arduino atemega168? you think it will feet balancing needs with the gyro and the accelerometers?!
i still thinking in get max1238 for some other sensors, and future expation, cause this adc its cheap and i think its powerful.. 12bits of sensibility its really nice, and i2c port will be hot.

can u share me your knows about max1238? it need to be programmed? it only support voltage differential or resistance differentials to?

thks for all the help Tracy Allen

Tracy Allen

I've attached a tutorial about the MAX1238, which I wrote a couple of years ago for a customer.

You asked about differential voltage. Yes, the channels can be set up for either differential or single ended. You asked about resistance differentials too. The resistances will have to be in a bridge circuit, and then the ADC will measure the differential voltages.

I don't know about those other microcontrollers, but you should take a look here at the SX and the Propeller, which are both very powerful and fast microcontrollers from Parallax, and both are well supported here on the other fora.

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Tracy Allen
www.emesystems.com

TigPT

ic ic.. thks for all info.. i will check your code [noparse]:)[/noparse]