lundi, décembre 29, 2008

Output 1 or 0

TTL logic gates are better at sinking current than sourcing current. What this means is that the output transistors of a TTL device work better when they connect a load to ground (0V) rather than to the +5V supply.

PIC microcontrollers are constructed of CMOS transistors as opposed to TTL transistor. CMOS circuits work equally well when connecting an output device to the high voltage side (+5V) as they do when connecting to the low voltage side. The advantage of an activehigh drive circuit is that it’s easier for a programmer to follow the logic that lights the LED. Making the PIC output 1, or a high voltage, turns the LED on. Making the output 0, or a low voltage, turns the LED off.

samedi, octobre 11, 2008

Debugging PIC

Unable to enter debug mode

For some processors, if Power Up Timer is enabled then this may unable to enter debug mode

For stable debugging, 4.7k resistors are needed from PGC/PGD to GND (on Pickkit 2 with red button, those resistors are already present)

samedi, septembre 06, 2008

lundi, août 18, 2008

Calcul poutres/solives

Flèche



Avec :

f = flèche en m
p = charge unitaire en N/m
L = longueur entre appuis en m
E = module d'Young en N/m^2
I = moment d'inertie de la section de la poutre en m^4

http://pagesperso-orange.fr/philippe.fichou/Poutre/poutre7.htm

http://www.coinduprojeteur.com/beton/cours_rdm.html
http://www.mecatools.free.fr/mecatools.html

http://www.steelbizfrance.com/prog/formu.asp


Poutres porteuses
E acier=210000 MPa
Charges
poutrains/claveaux (180 kg/m2) + chappe (175 kg/m2) + surcharge (350 kg/m2)=705 kg/m2
Poutre 1
L=4.8m, p=705*3.8/2*9.81=13140.50 N/m,f=4.8/300=0.016 m
  • I=27.0319 m4
  • HEB
Poutre 2
L=4.8m, p=705*(3.8+4.8)/2*9.81=29739,02 N/m,f=4.8/300=0.016 m
  • I=61.1774 m4
Poutre 3
L=3.8m, p=705*4.8/2*9.81=16598,52 N/m,f=3.8/300=0.01266 m
  • I=16.9419 m4


Surces: http://www.daniel.fr/prod_sid2.php?f=poutrelles/heb-26.htm

Charges 120 (temporaires) + 120 (permanentes) kg/m²

Portées en mmEntraxe
495 à 515 mm
4 000 75 x 225
4 500 75 x 250
5 000 100 x 250
http://www.bois.com/amenager/parquet-plancher/guide-achat-parquet/les-abaques-de-solivage

mardi, août 12, 2008

Calcul poutres acier

Type de poutre

HEB 200


http://www.groupdelrue.be/new/fr/default.htm

Poids: 62.5 kg/m

http://www.rocourt-metaux.be/fichesfers.htm

Poids: 62.5 kg/m
Charge maximale admissible uniformément répartie (Portée 5m): 10637 kg