Question on making a wtach with nrf52810

[OldXiao]

I have thought of making a simple but long time running watch before.

For I have finished a simple app on nrf52810,maybe I can make the watch now.

My basic idea:

1) use a glass cylinder to hold all parts;

2) use 1 AAA rechargeable Li-battery;

3) FPC pcb, so the pcba can round on the battery and installed in cylinder;

4) display yyyy mm dd hh mm ss;

5) use mini LED as displayer,compose the led like 7-segment digital tube,the LED surface must cover something,

MCU will scan and lighting these leds for a short moment when actived;

6) the date & time can be initionalised through BLE connection,send  " yyyy mm dd hh mm ss" to one attribute;

7) provide 1 button, display current time when pressed once,display date & time  for twice.

8) SoftDevice running only when button pressed, shutdown completely on other time;

9) the timing accuracy is 1 second, so wakeup every 1 second? 

There is 1 question: do we need the antenna?

Just 1 line on FPC is enough? For the distance between watch & mobile/PC is very short.

And advise me the start example which is good at power comsumption control.

Thank you.

[OldXiao]

As a 1st step, I want to create my BLE module based on nrf52810. For I have to compat the built PCB, so design a PCB to replace the E104-BT52(3rd vendor module).And I have no device to tune antenna, so replace the printed antenna with chip antenna.I customised it from the official version. Could anyone have a look at it and make sure it can work at the least,the distance is another issue,it is not so critical at this moment.

Chip antenna datasheet attached too. 

nrf52810_qcaa_cust.zip CA-C03规格书.pdf

[ketiljo]

A couple of issues:

!. You're missing the matching network, these components must always be there: 

Note how C3 here is grounded: 

2. The antenna have a specific layout you must follow as it meant to be mounted in the corner of the PCB

3. Place a GND via or two near the GND side of C4 and C9

Else you're good.

[OldXiao]

Thanks for advice.

The matching network is the part I have no idea.

There are standard circuit & layout from Nordic as you showed,but,chip antenna vendor has provided the circuit too:

I adopted above circuit:

These 2 circuit do the same thing? Or both of them are needed?

[OldXiao]

Looks like these two parts are needed,:Antenna

Matching network: C3 L1

antenna circuit: c14 R17 L4 antenna.

For mine:

Matching network: C3 L1 (in original design)

Antenna circuit: R1 R2 L1 (my current design)

Is that right?

[ketiljo]

Yes, that's correct

[OldXiao]

nrf52810_qcaa_cust_v2.rar

updated:

1) add matching parts;

2) re-arrange pins.

The path from nrf52810 to chip antenna gets longer.

Have a look,pls.

[ketiljo]

Very good!

If you are are using the same antenna, check with the manufacturer if it's ok to place it like this.