I fail to see how the diodes offer protection.
Sorry still don't understand, can you show the connections to the micro?.
Nigel Goodwin said:I take it you know that to turn the H-bridge ON you take the inputs LOW and not HIGH?.
I have shown the connections to the microprocessor (or to the prototyping board on which it is mounted, anyway): it's a complete schematic.
No, a logic high from port PXn is 3.3V. I'm bridging logic highs and logic lows to use the 3.3V output to control the transistors and switch the H-Bridges.
In which post?, #257?
There's hardly any of a circuit there.
Nigel Goodwin said:Where is the common ground connection?, and what do you mean by 'bridging'?.
I don't understand what you mean. That's the complete schematic. What is missing?
By 'bridging', I mean 'connecting'. I am passing a current between PA0 and PA1 (or vice verca) to activate the top BJTs.
It just struck me that I could simplify the circuit to remove D(n)b and D(n)c diodes now that only two of the transistors are being activated by the µP directly though; I should now be able to simply connect PA1 to the emitter of Tr1a, and PA0 to the emitter of Tr1b, which wasn't possible with the previous schematic. And of course, follow the same procedure for the others.
In fact, that should remove the need for any of the diodes... eurekait appears hero's modification to my original idea has made my ground return much simpler. I'll post a new schematic shortly.
You've not listened to half of what we've said.I give up.
to designing a circuit that the rest of us can't understand
my circuit is better because: it uses PNP transistors for the high side, the double high protection will work regardless of how many h-briges are used and it uses less components.
This where most of us parted ways.If you think my circuit won't work but won't provide a reason better than that it doesn't all connect directly to the µP's GND pin, then I don't want to know.
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