By having the range entire setup operate.3V, all these sensors can be user used without any tedious level converters.
A second reason for running.3V, is that you can use 3 AA batteries instead of 4 (either alkaline or rechargeable).
One recent example was the 555 oscillator used on the, infrared Plug : the original NE555 needs at least.5V, but theres an ICM7555 using cmos technology which works down to 3V, making it a non-issue.For these, you may have to use special level translator chips, or perhaps something like the I2C-based Output Plug, which can be powered with voltages up to 50V.In practice, I find that even with.7 x VCC, I can usually ventline drive a 5V chip just fine from a JeeNode.The manual real problem comes from the I/O interface.On the input side, there manual are two common cases.So much so, that not a single case has hood been reported where this has caused problems in any of the several thousand manual JeeNodes produced so far.This is good news for low-power uses, BTW.
The tricky part is logic 1,.e.
Which is the fourth reason why I decided to run JeeNodes.3V, BTW).
Well, it turns out that this may or may not game work by simply tying the two lines together.
The only case when things may or may not work reliably, is with chips which wars specify the minimum action logic 1 voltage to.7 x VCC or something like that.
It means you can get the same amount of work done using less power, since power voltage x current.JeeNode, unleashed odbc was to make it run.3V, instead of the 5V used by the standard Arduino.By placing a 1 k resistor in series, we limit the flow through the diode to under 2 mA, which most devices will throat handle without any problems: Ok, so now we can hook up signals to a JeeNode, even if they swing in the.5V.The main reason for this was the RFM12B wireless module, which can only be used with supply voltages up.8V, according to the specs.Most chips consider anything between 0 and.8V a logic low.With analog I/O,.e.The.3V output signal will definitely not damage a chip running.The worst that can happen, is that the 5V side doesnt consider the signal valid.I/O pin connected is also affected by this.On a 5V chip, that translates to a minimum value.5V Note that datasheets usually contain conservative range specs, meant to indicate limit values under all temperatures, load conditions, supply voltages, etc.These chips will be perfectly happy with the JeeNode signal.So whats the deal with.3V vs 5V?