Planning to buy a cheap Ebay USB to TTL (5v) converter to serailly program 3.3V eqipment.
I would like to use an opto isolator. Max baud rate 9600, can make do with 2400 baud if that simplifies it.
I'm hoping to use the opto isolator circuit as the (logic) voltage convertor as well as providing isolation.
Can anyone suggest a common, cheap & suitable opto isolator please?
I am happy to calculate the resistor values from the opto isolator data sheet (and post back here for comments).
Is it best to use the design below and pull the outputs low (it makes sense to me but that could just be my lack of knowlege). When the input is idling, the output will be held high anyway (?)
What concerns (if any) are there if the attached hardware has pull up resistors internally?
All advice and information greatfully received (even if tells me this is a non-starter).
Keith
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- circuit diagram
- opto.PNG (19.56 KiB) Viewed 7432 times
