pic16F887 Half Bridge problem

[aliaj00]

dont know how to attach screenshot here

[PCM programmer]

Go to a free image hosting service such as http://www.imageshack.com
and post it there. Then post the link here.

[aliaj00]

Yes I just uploaded it now.

http://imageshack.us/photo/my-images/823/506khzsofthalfbridgefix.jpg/

[PCM programmer]

Post your schematic.

[aliaj00]

It is just the pic debugger with the 16F887 on it. and on RB1 RB3 there are the darlington with 500 Ohm resistance on the base. I didn't made a schematic for it as it has fewer than 10 Elements.

[aliaj00]

Hi PCM programmer,

how can i insert a rs232 into the code to change the parameters but not to loop through it in the while statement, as i will be forced to enter an answer each time.

BR's

shpetim Aliaj

[Ttelmah]

Basic technique. Two 'modes' of operation.
'Normal' mode. Sit in your loop, and at one point do a 'kbhit'.
If this is true, read the single character from the serial. Then have a 'decision', so if (for example), the character 'C' is there, you switch to 'config' mode.
Then send a little prompt for the data you want, and read the return. With a bit of ingenuity (again kbhit, and a timer), you can have it that if no reply is seen in say 30 seconds, the code automatically returns to 'normal' mode.

On your circuit, what are the darlington's actually driving?. Is it inductive?. If so, what circuitry have you got to trap the energy stored in the inductor, when the transistors switch off?.

Best Wishes

[aliaj00]

the darlington are 2SD2390 each with 10 AMP of load or more. i attached the metallic radiator to them and also a cooler on each one of them as the heat generated was burning them "with only metallic radiator". i have tried with all loads, pure heater from old oven :P, Big COIL 2.5MM2 100 turns etc to test it. they have a diode from what i remember. i am not sure need to check.

[aliaj00]

i have tested in the 5.06Khz to 32 khz

[aliaj00]

can i put a push button on it and generate a interrupt so when i want to update the timing i can trigger the rs232 code and than to have it running without the rs232 routine.

BR's

Shpetim Aliaj

[Ttelmah]

No point in using an interrupt. Just have one instruction in your loop, testing if the input pin is in the 'active' state. If it is, switch to the config mode.
This is exactly like 'bootloader' code, where as the chip wakes up, an input pin is tested, and if it is in the active state, the code switches to the bootloader. Zero point (and several potential problems), trying to use an interrupt for this. Much simpler just to poll the pin.

Best Wishes

[aliaj00]

thanks a lot,

i am just new with the pics after PC programming, networking and electronic stuff.

PS. by the way do you have a code snippet for this.

[aliaj00]

i will try to put a bc557 and an irfp31n50l as the driver as it have 30AMP and use the bc557 as phase corrector.

[Ttelmah]

On the question of 'code snippet', not really. This is so basic, that there isn't much to show!...
Typical thing would be to have a button connected to a pin (say B2), pulling it to ground. Then have a pull-up on this pin (either use the internal pull-ups, or a resistor).
Then just organise your code as:

[aliaj00]

thanks a lot

i will do it.

i tested with the bc557 and irfp31n50l and it seems to work not much measuring but at least it still not burned. i got an 2n3440 and will try it with the irfp31n50l. maybe it has better response time.