Hello,

I see two issues with this schematic. 1) The Cap C3 looks like it says 100nf. In the non-amplified use, this should be at least 4.7uF. If you are using a PA I would suggest a even larger value be used.

PO.25 and PO.26 if not used should be tied to ground. If used then they should each have a 12pF cap to ground. The internal bonding wires on the QFN package picks up some stray RF and will probably not pass any agency testing in Korea or Japan. This is probably not that important for personal use.

@absolem Check out the css811 sensor. It can detect CO2 such as we al know we exhale with every breath. This is the same device used on the Nordic Semiconductor “nRF52 Thingy”.

http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.rds%2Fdita%2Frds%2Fdesigns%2Fthingy%2Fhw_description%2Fhw_descr.html

@neverdie And it has the 32Khz crystal on it too which will reduce power consumption. And It looks like the DC/DC converter is also included?

@nca78 There is no downside to using the nRF52810. It depends on your needs. If you can live with 192K Flash and 24K RAM and a stack that supports peripheral only (at this time) then you are good. The device can use the internal 32Khz RC osc for BTLE and there is a slight current consumption hit as the receive window will be longer. (+/- 500ppm) . No different then on the nRF52832. as stated, a 32Khz crystal will give you a tighter clock and lower current consumption.

This is a scaled down version of the nRF52832 so there are some peripherals that have been taken out or reduced. PWM for example, only one. No NFC, 1x SPI Master or Slave, (instead of 3), No I2s...... The full datasheet and product briefs are available on Nordic's website so you can A-B the features.

@nca78 The Rev C (COO) parts are available now and they are the production parts. (Symmetry and Nordic's other distributors have these in stock) There will be a respin of this to a Rev D to fix the REG0 issue. FYI, the current nRF52840 package is not a WCSP. It is a aQFN package. The nRF52840-Dongle is also available now. Go forth and design......

@alexsh1 These boards support the Jlink (Segger) environment. The Segger firmware is available for windows, linux and MacOS..https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPa

@scalz
I would be interested in any range testing in regard to this dongle. For ground it has whatever it is that it is plugged into. (PC, SBC, USB extention cable, etc) There will be a nRF52840 based dongle out soon. See picture above. This dongle will need to be programed over the SWD lines. No Segger on board this one..!

@artag The nRF51802 QFAA has 256k Flash and 16k RAM. It is pin to pin compatible with the nRF51822QFAA in the QFN48 package, 6x6 mm. Note that some of the parameters for the nRF51802 are slightly looser then the nRF51822. (Current consumption, wakeup time, sensitivity)