RFSensor

[openhardware.io]

https://www.openhardware.io/view/29/RFSensor

[jbjalling]

Hi all,
I will upload the projectfiles soon. I'm still waiting for the PCB's to arrive, and I want to make sure that it works (at least to some degree) before I release the files - hope its OK.

BR Jonas

[GertSanders]

@jbjalling You could upload the schematic already and add the rest later.

[jbjalling]

Great idea. I'll upload it tomorrow.

BR Jonas

[jenbaker]

hi

i am new in this field.
hope to learn from each other here.

could i embed it into these any rfid reader ?

waiting for help.

[jbjalling]

@jenbaker Hi,
well, it could be possible to embed it in a RFID reader, but it isn't really the purpose of the device.
It is intended to be a stand-alone environment sensor.

BR Jonas

[jenbaker]

@jbjalling
hi great.
thanks.

[alexsh1]

hi

any update on schematic please?

Thanks
Alex

[jbjalling]

I have uploaded the Rev. 1.0 schematic. I'm currently making some small changes, to be able to use the RF69 module as well as the nRF24L01+.

[GertSanders]

I see that you use ADC7 to power the BPM180. This will not work, ADC7 is an analog sensing pin only and can not be used as digital output (same for ADC6). Better to use PD4, which is still available in your v1 schematic.

[GertSanders]

@jbjalling I do not really understand why you need 2 FETs to switch the nrf power line. How do you see this work ?

[jbjalling]

Yep, thanks. Found out the hard way I'm not sure if I really want to power the sensors from the micro. I have to turn on every sensor to be able to use the I2C bus, so I cant turn them on selectively, as I had hoped.

BR Jonas

[jbjalling]

I use the N-fet to drive the P-fet, which powers the radio module - again, I'm not sure if its worth it, but when the power comes from a coincell, every nA counts.

/Jonas

[scalz]

nice work. for UV, I prefer VEML6070, a lot more precise but not same price and not ambiant light
I agree with @GertSanders too, you just need one pfet for powering off radio..

[jbjalling]

@scalz Yes, the Vishay one is more precies indeed, but my main reason for putting the Silabs one on the board, was to detect the ambient light level.

Reg. the mosfet, yes I could have used a single fet. I think the reason why I did it like this, was that in a previous project, I was controlling higher voltages, hence the need for the n-fet.
Anyway, I'm not sure if I will keep it or if I will just let the radio be powered on, all the time, in the next rev.

BR Jonas

[jbjalling]

I have updated the schematic to rev. 1.1.
The following has been changed:

• Si1133 has been replaced by Si1145
• The mosfets are removed from the radio power path
• Radio pins shuffled around a bit
• FTDI connector removed from PCB and instead I made a programming jig
• All I2C sensors are powered from the same pin of the uC, as well as the I2C pull-ups (haven't decided which pin yet, still routing the PCB)

Comments are more than welcome.

BR Jonas

[MiKa]

Hi,
possible to share pcb files?
THX
MiKa