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Messages - exapod

46
Project logs / line follower with dspic33fj128mc802
i'm planning of building a robot with a dspic33fj128mc804 and two encoders for implement some dead reckoning algorithms so for learn something on the dspics i build a line-follower, it uses 6 analog sensors that are read with the auto-scan capability of the chip, the pwm is 12 bit and the control loop runs at almost 30 kHz (it only calculates the line position and the do a very simple PD routine that use fixed point math).
The controller runs at almost 40 MIPS.
I win most of the parts on the sparkfun freeday :D.
Here it is a video : http://www.youtube.com/watch?v=B0XdQ6GRexo&feature=plcp .
52
Project logs / Re: TV-B-GONE
i build a prototype using the schematic of the pdf and it works great.
It has a range of more than 20m and it doesn't lose power with the time, the capacitor is a 200uf 4v that i desolder from an old remote, the led is a tsal6100.
I still need to put a smooth capacitor on the line but it works fine also without it.
Now i'm designing the board in eagle.
53
Project logs / Re: TV-B-GONE
i am building the second version with the cr2032 but this time i want use only one led.
I'm writing this because i need help for calculate the costant current driver.
I don't know if, for this configuration , is better a transitor or a mosfet.
I already have a couple of 2n2222 and this mosfet http://docs-europe.electrocomponents.co ... e5615d.pdf . What should i use?
This is the led http://docs-europe.electrocomponents.co ... e1b0e6.pdf .
I also find this document and it use a different way to power the led http://www.ti.com/lit/an/slla175/slla175.pdf .
Thanks for the help.
56
General discussion / small gps module
i'm building a datalogger around the pic24fj64gb002 that saves the data from an accelerometer, temperature sensor, and a gps on a micro sd card and has also an usb port for configure the device and also for print the data if the pc doesn't has an sd card slot.
I want the device to be as small as possible so i'm searching a small gps module (max 18mmx18mm and very thin) that can be soldered directly to the pcb and works on 3,3v.
Thanks for the help.
57
General discussion / Re: read two encoder
i think i will use timer0 and timer3 as 16 bit counter and i set timer1 to x second and every time the interrupt fires i do in the isr tick from the encoder / x second so i now the speed of the tho wheel
58
General discussion / read two encoder
hi,
i'm planning of doing a robot with two motors and two encoder.
for the motor part there is no problem but i don't know how interface the pic (a 18f4620) to the encoder.
I was thinking of using timer 1 and timer 3 as counter but i dont understand if i can use them in the same time and how.
the encoder give only one square wave that at maximun speed of the motor has a frequency of 2khz.
59
General discussion / Re: sd card datalogger
i use this code:http://www.d.umn.edu/~cprince/PubRes/Hardware/SDcard/ and interface correctly with a micro sd card.
Now i have another question, i need to read the analog value of the x,y,z axes of the accelerometer every 0,25 s but i don't understand how i can wake up the pic and then read the values. If i use a timer then how can i step in the main?
60
Project logs / Re: TV-B-GONE
i'm working on a version with two AA as power supply and 4 leds

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