💬 Easy/Newbie PCB for MySensors

[simbo]

Hi All,

Thanks Sundberg84 for creating a board where I can knock out sensors in the matter of minutes instead of hours. :)

That being said, I actually spent many hours on the weekend trying to get my first board to work so I thought that I'd share so it could benefit others.

I was setting up a 3v3 board with 2 x AA batteries with the battery pad jumpered and using the 3v3 booster. I triple checked the board for continuity.

I was suffering from !TSM:FPAR:FAIL messages when firing up the node using the FTDI adaptor. I found that the board didn't work when both the battery and FTDI were supplying power.

Here are my lessons:

• You need to have a battery connected. This is required to power the radio, as it radio isn't powered by the FTDI adapter
• You need to remove power from the FTDI adapter. I couldn't disable power on my FTDI adapter so I had to use jumper wires for CTS, DTR, RXD, TXD, and GND between the adapter and the ProMini.

Thanks again, and I look forward to knocking out some nodes super quick.

Cheers,
Simon.

[sundberg84]

@dbemowsk what I'm worried about is the booster so close to the radio. What do you think @dbemowsk @scalz @Nca78 ?

[gohan]

how about swapping the Extra and Booster section? It makes it cleaner to connect the extra pins to the pro mini.

[scalz]

@sundberg84 i think you already know the answer 😉 (not great regarding emi radiation for example,especially with cheap regulators and inductors.., one downside of relying on external parts,modules but i know your point it's for noobs..)
I seem to see another thing for your nrf ant, not sure if your nrf 24 goes outside the pcb,if it doesn't then this means you have gnd pour under the ant, not great too in this case

[dbemowsk]

@gohan & @sundberg84 For that matter, what about just swapping the Bat.measurer and the booster. You are going to get interference with the inductor being directly next to the antenna.

[sundberg84]

Thanks guys! (@scalz @gohan @dbemowsk !)
I think I will relocate the booster... should have thought about that before.
The NRF antenna goes outside the PCB just like rev 9 so no ground plain for the antenna in normal cases. I might revert it back to allow the PCB to be in range for all directions. Good point.

I will start with to swap extra and booster to get as much space in between the antenna and inductor.

[sundberg84]

Something like this...

[dbemowsk]

Would something like this be possible? It would give users that little bit of extra room in the proto area.

[sundberg84]

Hi all!

This has now been update to Rev 10.
New revision has been sent to PCB manufacturer but It will take some days for them to update their Gerber. (When you order, make sure it says M.Rev 6!

Openhardware page has been updated, let me know if you find anything strange.

RFM69 version will be updated soon as well.

[APL2017]

Can you please share design of version 9 of the Easy PCB NRF24 edition. I bought 10 pieces a while ago but just decided to use couple. Thank you.

[sundberg84]

@apl2017 what kind of info are you looking for ? Schematics ?

[APL2017]

Just schematic and board layout, exactly what you placed, if possible in a bit better resolution. Thanks a lot!

[sundberg84]

@apl2017 traveling for my work until next week but will post then.

[Mister_ik]

@sundberg84 I just finished my first battery sensor node based on the Easy PCB Rev 9. I have two questions i hope you can help me with:

The first is about the battery measurement. Because i didn't have a 0.1 uf lying around i used an 0.2 uf capacitor. I am using the following script to measure the battery.

//=========================
// BATTERY VOLTAGE DIVIDER SETUP
// 1M, 470K divider across battery and using internal ADC ref of 1.1V
// Sense point is bypassed with 0.1 uF cap to reduce noise at that point
// ((1e6+470e3)/470e3)*1.1 = Vmax = 3.44 Volts
// 3.44/1023 = Volts per bit = 0.003363075
#define VBAT_PER_BITS 0.003363075  
#define VMIN 1.9                                  //  Vmin (radio Min Volt)=1.9V (564v)
#define VMAX 3.0                                  //  Vmax = (2xAA bat)=3.0V (892v)
int batteryPcnt = 0;                              // Calc value for battery %
int batLoop = 0;                                  // Loop to help calc average
int batArray[3];                                  // Array to store value for average calc.
int BATTERY_SENSE_PIN = A0;                       // select the input pin for the battery sense point
//=========================   


   // Calculate the battery in %
   float Vbat  = sensorValue * VBAT_PER_BITS;
   int batteryPcnt = static_cast<int>(((Vbat-VMIN)/(VMAX-VMIN))*100.);
   Serial.print("Battery percent: "); Serial.print(batteryPcnt); Serial.println(" %");  

Do i need to change anything in the formula? Because i getting reading around the 130%

Requesting temperature...DONE
Temperatuur : 26.62 Degrees C
11935 TSF:MSG:SEND,25-25-0-0,s=5,c=1,t=0,pt=7,l=5,sg=0,ft=0,st=OK:26.6
Battery percent: 131 %
Battery Voltage: 3.35 V
Sleep...
12945 MCO:SLP:MS=900000,SMS=0,I1=0,M1=1,I2=254,M2=1
12955 TSF:TDI:TSL

If i use the following method:

//----
   // 1M, 470K divider across battery and using internal ADC ref of 1.1V
   // Sense point is bypassed with 0.1 uF cap to reduce noise at that point
   // ((1e6+470e3)/470e3)*1.1 = Vmax = 3.44 Volts
   // 3.44/1023 = Volts per bit = 0.003363075
   float batteryV  = sensorValue * 0.003363075;
   int batteryPcntNEW = sensorValue / 10;

   Serial.print("Battery percent: ");
   Serial.print(batteryPcntNEW);
   Serial.println(" %");
//----

I am getting: (this is expected, because batteries are new)

Battery percent: 99 %
Sleep...
12945 MCO:SLP:MS=900000,SMS=0,I1=0,M1=1,I2=254,M2=1
12955 TSF:TDI:TSL

My second question is about casing: any tips on which case to use which fit your board and a battery pack? and is as small as possible? Do you perhaps have links of your favourite (Chinese) sellers?

[Nca78]

@mister_ik said in 💬 Easy/Newbie PCB for MySensors:

@sundberg84 I just finished my first battery sensor node based on the Easy PCB Rev 9. I have two questions i hope you can help me with:

The first is about the battery measurement. Because i didn't have a 0.1 uf lying around i used an 0.2 uf capacitor. I am using the following script to measure the battery.

Do i need to change anything in the formula? Because i getting reading around the 130%

Hello, this is normal as your maximum voltage is set at 3V, while initial voltage of an alkaline AA/AAA cell can be a bit over 1.6V. But voltage will quickly drop toward 1.5V (much faster than remaining capacity), so the best instead of changing the maximum voltage is to check the value of batteryPcnt and if it's over 100, just set it to 100.
Make sure the VBAT_PER_BITS makes you read a voltage that matches the voltage you read with your multimeter, else fix it. Each Atmega is different so you need to calibrate each board.

For the capacitor it's not a problem, it's just made to stabilize the voltage as it's very sensible to electrical noise. Twice the value will be good enough for this job :)

[sundberg84]

@Nca78 thanks for the help/answer. 😀 About the case I'm using some plastic electronic cases from my hardware shop but @ openhardware you will find some links to 3d projects.

Let us know @Mister_ik if you need anything else.

[mickecarlsson]

No sign of the new revision yet:

[sundberg84]

@mickecarlsson - not on the RFM69 version, no. PCBway has updated the NRF24 version so a good sign.
Something went wrong with the update of the RFM69 version so I had to activate it 21hours ago:

Lets hope PCBway picks this up today.

[mickecarlsson]

@sundberg84
OK, good news. I will check it tomorrow and hopefully order a batch (or two).

[mickecarlsson]

Still no rev 6 on itead or pcbway for rfm69 version :-(