nRF5 action!

[NeverDie]

@Nca78

Unfortunately, I don't think the da14580 will work with the current mysensors library: it appears to be bluetooth only. I only did a quick speed read of its datasheet, but I didn't see any mention of the Nordic proprietary modes (or anything like them) that the mysensors library relies on.

[Nca78]

I have ordered one like this. It's pretty small already, less than 2*1cm :
https://www.aliexpress.com/item/nRF51822-04-BLE4-0-WIFI-Wireless-Bluetooth-Module-TTL-Low-Power-Consumption/32682158906.html

It has very limited I/O and is made to be used in addition to a MCU using UART to communicate, but the SWDIO and SWDCLK pins are broken out so I will see if I can reprogram it.
It has a datasheet to at least get a valid footprint (as I don't plan to use the serial protocol) :
https://4tronix.co.uk/picobot2/WT51822-S4AT.pdf

And it has been featured on Nordic's website where they say it's supposed to have FCC certification (and CE too, but that's just declarative...).
http://www.nordicsemi.com/node_206/node_305/Product-Related-News/Nordic-powered-Bluetooth-Smart-module-simplifies-development-of-wireless-wearables-toys-and-smart-home-solutions

They also claim a 50m range which is way better than the 10m of the da14580 you link above.

So if it can be reprogrammed without problem it looks like a perfect candidate for basic nodes like door, I2C etc

[NeverDie]

@Nca78

Both the price and size are certainly nice. I think d00616 would probably point out that it lacks a 32Khz crystal, but since I lack experience with the nRF5's, I don't know how significant that is or isn't. Anyone know?

BTW, it would also be nice to know whether or not the OTA sketch upload capability will work on an nRF51, or only an nRF52 (and also whether it will work on an nRF52832 or only the future nRF52840). Anyone know?

[Nca78]

@NeverDie said in Minimalist SAMD21 TQFP32 Pro Mini:

@Nca78

Both the price and size are certainly nice. I think d00616 would probably point out that it lacks a 32Khz crystal, but since I lack experience with the nRF5's, I don't know how significant that is or isn't. Anyone know?

Right, it sucks for low power at it needs recalibration every 4 seconds to stay accurate enough, generating 10uA extra consumption. But I'm not sure if this is needed for bluetooth only (because it has to wake up regularly and listen during a precise time window), or also for "nrf24" mode because in that mode we don't need to be precise or regular listenin.

[d00616]

@NeverDie said in Minimalist SAMD21 TQFP32 Pro Mini:

BTW, it would also be nice to know whether or not the OTA sketch upload capability will work on an nRF51, or only an nRF52 (and also whether it will work on an nRF52832 or only the future nRF52840). Anyone know?

Nordic's DFU bootloader is also working with nRF51 chips. https://devzone.nordicsemi.com/documentation/nrf51/4.4.1/html/group__bootloader__dfu__description.html

At the moment the MySensors implementation is not compatible with a SoftDevice. This requires to change interrupts, use some SoftDevice system calls and move the NVM driver Flash area out of the DFU bootloader area.

I have started a new thread for OTA update discussion: https://forum.mysensors.org/topic/7146/nrf5-ota-updates

@Nca78 said in Minimalist SAMD21 TQFP32 Pro Mini:

Right, it sucks for low power at it needs recalibration every 4 seconds to stay accurate enough, generating 10uA extra consumption. But I'm not sure if this is needed for bluetooth only (because it has to wake up regularly and listen during a precise time window), or also for "nrf24" mode because in that mode we don't need to be precise or regular listenin.

That's correct. If required, the calibration task must be implemented or is part of the SoftDevice. At the moment the radio doesn't require a precise RTC for nRF24 compatibility. For battery powered sensors listening for commands a time slotted protocol is required. Then this protocol relies on a precise RTC.

[NeverDie]

I'm leaning more toward the nRF52 platform over the nRF51, in part for its superior range but also because I'm guessing it will be a little easier for the person who is implementing the OTA sketch uploads to implement it first on an nRF52 (more resources, less constrained).

[NeverDie]

So, is the speed of the Cortex on an nRF5 already good enough that one can simply emulate an atsha signing component, and thus that part now completely disappears from the BOM?

[Anticimex]

@NeverDie you can run soft signing on any device. It emulates the atsha204a equally well. The performance of the MCU only affects the speed of the calculations, not the quality of the result.

[Anticimex]

@NeverDie but remember that if you use soft signing it is your own responsibility to protect the hmac key from readout by an attacker with physical access to the device.

[NeverDie]

@Anticimex said in Minimalist SAMD21 TQFP32 Pro Mini:

@NeverDie but remember that if you use soft signing it is your own responsibility to protect the hmac key from readout by an attacker with physical access to the device.

Thanks! Good to know. Speaking only for myself, I don't think I'll be losing any sleep over the prospect of an attacker gaining physical access to one of my home devices with the intent of extracting the hmac key. I'm more likely to win a lottery than have that happen--and I don't even play lotteries.

[Anticimex]

@NeverDie that is probably correct, I just feel a responsibility to inform everyone of any known weaknesses in the security infrastructure ;)

[NeverDie]

@Anticimex
I don't mean to trivialize it. For commercial applications, the atsha204a would of course make sense.

But, at least for now, it sounds likely that $2.73 will buy you the hardware for a nice little home wireless node, minus sensors and power supply. That's today's price for a NRF51822-04 MINI that NCA78 linked to above. And, of course, that price will continue to drop. Pretty cool!

[NeverDie]

Which library is most recommended for exploiting the RTC that's on an nRF52832? Likewise, what's the best library for sleeping the nRF52832? Since I have the DK, I'd like to take some current measurements while running some demo code for that. That will establish a baseline for comparing future measurements.

[NeverDie]

I just now ordered this:
https://www.sparkfun.com/products/13746?_ga=2.39569123.1141912816.1499956888-1087552930.1495048698

It's like a regular FTDI, but it can also power your project at 3.3v at up to 600ma! :) Previously I had to make my own hacked FTDI interface to do that. Ordinary 3.3v FTDI's will burn out under the load of, say, an ESP8266, or a 20db Tx power amplified nRF24L01.

[d00616]

@NeverDie said in Minimalist SAMD21 TQFP32 Pro Mini:

Which library is most recommended for exploiting the RTC that's on an nRF52832? Likewise, what's the best library for sleeping the nRF52832? Since I have the DK, I'd like to take some current measurements while running some demo code for that. That will establish a baseline for comparing future measurements.

Sleeping is implemented by hwSleep(). This function uses one RTC. If you need advanced RTC access, you have to cooperate with this RTC, because the interrupt routine must reset the state registers. On nRF51 the other RTC is used for millis(). The nRF52 has one RTC free.

[NeverDie]

In case anyone else either has, or is thinking of getting, the nRF52832 DK, it looks as though there is indeed a way to use its programmer to program an offboard nRF52832 without desoldering the nRF52832 that's on the DK. Here's the existence proof photo where an 832 DK is being used to program Sparkfun's nRF52832 breakout board over the two SW lines:

The caption reads "For faster programming, an nRF52832 Development Kit can be used to program the nRF52832 Breakout Board."
I haven't yet found the instructions on how to do it though.

[NeverDie]

@NeverDie said in Minimalist SAMD21 TQFP32 Pro Mini:

@d00616
9mmx9mm would be great. However, are you certain?

I'm convinced! I pulled this picture off the FCC website, and, indeed, it is 9x9mm:

(https://fccid.io/2AA72-PTR5628)

So, thanks for mentioning its size, or else I never would have known!

[NeverDie]

So, what's the smallest nRF52 module that also includes a 32Khz crystal? I think I might want to standardize as much as possible on a single module rather than juggle a bunch of different ones.

[d00616]

@NeverDie said in Minimalist SAMD21 TQFP32 Pro Mini:

So, what's the smallest nRF52 module that also includes a 32Khz crystal? I think I might want to standardize as much as possible on a single module rather than juggle a bunch of different ones.

What do you think about creating an table with known modules including integrated hardware, available ports and size?

I think, most small modules comes without 32kHz crystal. This is mostly an option. Maybe for the 9x9mm module. But I think the antenna is no good choice for indoor usage.

I have a lot of RedBear BLE Nano 2 (18x21mm) modules. It's complete including 32Khz crystal and a 3-13V voltage converter. With 2.54mm pins it's easy to solder.

I have asked the manufacturer(cdebyte) of the nice nRF24 and nRF52 modules if it's possible to build an module including the nRF52, an RGB LED, an button and 5V protected inputs with the layout like the popular nRF24 modules plus two optional pins (6/8 IO Ports!). I think such type of nRF52 module makes it easy to migrate to 32 Bit using existing boards or build new boards.

[NeverDie]

I just now noticed that Ebyte also has a storefront on aliexpress.
https://cdebyte.aliexpress.com/store/2077046?spm=2114.12010108.0.0.7Yid4a
For me, it's much better than ebay, because it includes free e-packet delivery to the US. So, unlike ebay, I will hopefully get their modules much sooner than September! The estimated delivery time from Ebyte if ordered through Aliexpress is 12-20 days. :)
https://www.aliexpress.com/store/product/CDEBYTE-E73-2G4M04S-BLE-4-2-5-0-long-distance-100m-2-4GHz-SMD-ARM-Core/2077046_32820692238.html?spm=2114.12010615.0.0.TZClHR

[Edit: Also, on Aliexpress, Ebyte gives a coupon for $5 off if you order >$45]