using ports as power supply

[vvarlord]

i've worked out a project with atmega 8,and it uses rs232 to commuinicate with computer(matlab)
i use a seperate power supply for it
my question is can i obtain the power needed for my circuit from the port?
i use a usb port which then a usb2com converter is installed on it, and where it's connected to micro uses D9 connector
i checked all the pins but 3.3 is the max voltage on them
tnx in advance

 

[tpetar]

You can use power from USB. Voltage is 5V and if you need 3,3V use adequate voltage regulator.


Best regards,
Peter

 

[vvarlord]

i can't use the usb directly
because the usb cable is connected to a usb2com convertor which converts the usb to a standard serial com port D9 connector
could i obtain power from that?

 

[tpetar]

Make your convertor inside your device on your PCB, you need one chip FT232 and few caps. On that way you can use 5V from USB.

Best regards,
Peter

 

[vvarlord]

i don't have access to buy FT232 IC
i just but a ready to use converter
D9 pins cannot be used as supply?

 

[tpetar]

I think it is not possible.

But you can use another USB connector which will get power from other USB port.


Best regards,
Peter

 

[vvarlord]

that demand 2 port useage
i think the seperate power supply is better thanks anyway
tnx

 

[tpetar]

Yes, but not necessary if you use Y cable.

Best regards,
Peter

 

[vvarlord]

i had a another question that is not related to this topic
im simulink of matlab, i've created a model
but i want to use that model with the same timing of my circuit
i mean i want to use it where i can define the time step of 1second for some blocks
is it possible?

 

[tpetar]

You simulate with a more restrictive version of the universal computational tradeoff of accuracy versus speed.

The simulation execution time per time step must be consistently short enough to permit any other tasks that the simulation environment must perform, such as reading sensor input or generating output actuator signals. This requirement must be satisfied even if the simulation changes its qualitative character: the system stiffness might change, and discrete components can switch states. Such changes occasionally require more computations to achieve an accurate result.


Run Real-Time Model
**broken link removed**

Real-Time Simulation
**broken link removed**


Best regards,
Peter