In my case the question is about EMX module, but I guess it should be applicable to any other module/CPU :
I get a one-wire temperature sensor DS18B20 and it works great :
It is wired as shown below and here is the documentation : http://docs-europe.electrocomponents.com/webdocs/002f/0900766b8002ff48.pdf
static OutputPort pinTemperature = new OutputPort((Cpu.Pin)Pin.IO47, true); static OneWire owTemperature = new OneWire(pinTemperature);
Question is : Is there possible to use one-wire sensors without this 4k7 external pullup resistor?
Maybe forcing by software the internal PullUp of EMX/LPC24XX on this pin? Unfortunately, I have no control of that with the MicroFramework built in one-wire class, even if I expect that the internal pull-up is enabled when the One-Wire constructor is called, but is a “weak” pullup made with poor transistors (as told in LPC24XX doc)
My problem is that I want add several of those one-wire sensors on my existing boards but on pins where there is no physically pullup wired on them. Since we have already buils ~100 boards and we don’t want to modify each of them ( i.e. add manually pullup on each)