I received my nRF52840 PDK from Symmetry Electronics right after Christmas. I have been doing some basic Bluetooth / BLE 5 experiments (including building a sniffer) recently. 
 
A note on Symmetry Electronics ... They were running a promotion before Christmas in offering discounts and free shipping on Nordic Semiconductor development tools. Long story short, they screwed me out of free shipping. I won't go into the gory details, but suffice it to say that when I checked out my purchase from their website, it clearly showed my shipping was free. And then it wasn't. I can NOT recommend them as the most honest / trustworthy distributor to order Nordic supplies from. Just my personal experience. 
 
The board... 
 
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The part... 
 
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Posted by: Lab Coat

So I have (had?) a few (6+) of the older nRF51822-EK dongles hanging around the shop, and was recently using one related to some BLE sniffer hackery (more on that later). As I was getting the code running, I noticed that one of the timers (Timer0) was acting peculiar. No matter what bitmode I set the timer to, it was always counting in 24bit mode ... long story short, I was directed to this - https://devzone.nordicsemi.com/question/1310/nrf51822-bit-width-and-bitmode/ Basically Timer0 of the rev1 and rev2 Si of the nRF51822 was broken. So, what does any good engineer armed with a shop full of expensive re-work equipment do ... re-work. 
 
I removed the nRF51822 Si off these and replaced them with nRF51422 QFAB A1 (rev3) Si ... works(ed) like a charm. I do have access so several nRF51 Dongles (newer style), but why throw these way when they can easily be updated. The only difference between the '822 and the '422, is that the 422 supports ANT (along with BLE). 
 
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Funny. Looks like there were a few nRF52s (nRF52832 QFAA AA) in there. I had 2 nRF52 Preview Development Kits that had engineering samples of the nRF52 on them. Again, why throw them out when they can be easily updated with new Si. 
 
A little closer ... 
 
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Posted by: Lab Coat

Speaking of CES2017 and all of the Apple HomeKit - kit, here is an older device for your viewing pleasure the HomeKit compatible iDevices Switch. I picked these up at Home Depot this past fall on clearance. Three were purchased for $13.03 (from $49.99) and one was purchased for $0.01 - that's right, I purchased one for a penny. 
 
Side story about Home Depot clearance pricing - when a product reaches $xx.03, it's essentially gone (or going to be gone very very soon). At the next markdown interval, the store reset team marks them down to a penny and that is managements cue to literally clear them out (as in one destination is the trash). I "caught one" still on the shelf that showed $13.03, but the computer had already marked it down to $0.01. SWEET! 
 
Without further delay... 
 
Box. 
 
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Markdown price for 3 units... 
 
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Guts. Pretty sure the smt IC in the lower left is an Auth IC. Seems to have numbering that I recognize (For complete disclosure, I have a license, but I don't divulge details). A few Broadcom parts. 
 
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After the teardown, I'm not sure how I feel about this unit. Seems to be very well built, which is good ... however, can a thing be too well built? 
 
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Posted by: Lab Coat

So I purchased 2 of these units on eBay [I think I paid $30-ish each ... the ~$150 "normal" price tag is crazy] to tear one down to see what they used for the BLE comms. Unsurprising that they used the NRF51822 (QFAA H0 - Rev 3 Si) ... what was curious was the use of the AFE4400 from TI. If the development company had used a different sensing element (say an Si114x series from Silicon Labs), they would have had a less-expensive / less-complicated straight forward design. Oh well, they didn't ask us.  
 
 
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Here is the basic photodiode-with-2-wavelength-leds setup... 2 LEDs to generate the 2 different wavelengths for pulse oximetry. One LED emits visible red light (typically around 600nm), and the other LED emits near infra-red light (typically around 900nm). Interesting that they appear to use a thermistor to see if the sensor is still on the child's foot.  
 
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And, this is what is typically used in a hospital environment (sans finger wrap) ... The LEDs are contained within one package shown on the left (as you forward bias the device, you get one wavelength, and if you reverse bias it, you get the other). 
 
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Posted by: Lab Coat

Did you know that the Misfit Flash has an nRF51822 device at it's heart? I do. And when repurposed, they make great little devices for beacons, or temp monitoring, or acceleration measurement (via the built-in LIS2DH), or a single button remote, etc. Here are a few pics ... I'll try to include the code and pinouts (for the LED's / switch / accelerometer) at a later date. 
 
Anyone know why there is the symbol for "Sputnik" on the silkscreen? Just curious... 
 
 
 
 
 
 
 

Posted by: Lab Coat