Newbie PCB and battery on RAW Voltage measurement
Re: Easy/Newbie PCB for MySensors
I am building my first Newbie PCB sensor. I am powering with 9V battery on RAW and let the onboard pro mini regulator supply 5V. I am not using a booster.
I would like to use the battery measurer voltage divider. I recalculated the resistor values to 5M/680K.
Looking at the schematic of Newbie PCB I see that when the BAT and REG jumpers are NOT connected and also the REG power input is NOT connected I could use the unused booster pin 1 as input for the Voltage divider.
I would think when jumpering the RAW pin to the not used pin 1 (Vin) of the booster connection I could measure my RAW battery voltage.
Just looking for confirmation.
@peerv you can use the booster pin to read the battery voltage or the proto board area. May I ask why are you going to make a battery powered 5v node? That is going to drain battery quite quickly.
drain battery quite quickly
and 9V isnt a very good choice as well.
the problem is that most Arduino boards use a linear regulator to drop that 9V to 5V. If you are drawing a mere 50mA, 0.2W is being burnt in this linear regulator with 0.25W being used by the Arduno itself. This is very inefficient!
An alkaline 9V PP3 has a capacity of between 500 and 600mAh. This really isn’t very high – a typical alkaline AA battery will be at least 2000mAh. 6 series AA cells will provide the same voltage, but a capacity at least 4 times the size!
I have tried it myself - will never do it again. And that was with a 3.3v pro mini.
BAT and REG jumpers are NOT connected
These jumpers are made for different applications. Using RAW as source you should not bridge/connect any of these. The current will flow from RAW (in) to arduino RAW where it will be converted to 5v. You then need a second voltage regulator for the radio 3.3v.
I would think when jumpering the RAW pin to the not used pin 1 (Vin)
This would add a second application and VCC to your pcb. I would take @gohan advice.
@gohan I am using the sonar distance sensor to measure water level.
The measurement is only taking once every minute.
So the sensor is sleeping most of the time.
To save power I power the sonar from a digital pin.
Before going to sleep I switch off the sonar.
In sleep mode my sensor draws only 200 micro amps!
Thanks @gohan for the link tip.
I will see how long the battery last in this application.
200 uA is not very low, usually you should aim at 10 or less, so there has to be something that is drawing excessive standby current
@gohan I managed to get it down to 40 microamp in sleep mode now.
I also read somewhere to set all unused pins to INPUT.
I am going to try that too.
@peerv - 40uA is what I aim with a Pro Mini 3.3v, sensor, radio and EasyPCB. Should last you a long time! GOod work.!