@chipmc - Good stuff. I appreciate the link! Thanks! It’s much easier picking out a cap like this or really any components when you know someone who uses it with success already!
I already have the earlier version of Deep Reset tutorial already integrated into my PCB… and in a few days was placing another order of PCBAs. It’s tempting to switch to the RTC Enable circuit. I wish I would of found this earlier. I need to spend more time on these forums than I do I always find a few great nuggets like this on here.
@chipmc [quote=“chipmc, post:202, topic:48750”]
Yes, exactly. The idea is that with an RTC on the Enable pin, you can use it for both low power “Enable” sleep and as a deep reset mechanism.
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I read through the document a few times… my understanding is the external RTC isn’t necessarily for Enable Sleep but rather allows for nRF52 MCU “Hibernate” type sleep. When it enters Hibernate sleep, at the specific time of day, it then wakes up due to an interrupt on D8 (Or whatever pin is wired as the interrupt). In this case, it allows us to leverage the lowest possible level of power “Hibernate” while keeping track of the RTC separate than the main Boron RTC since that stops during Hibernate.
I was thinking I could still use this short sleep durations and the the cellular modem would not have to renegotiate after a short sleep duration (<20 minutes). However, then the docs set me straight. “On cellular devices, the cellular modem is turned off in HIBERNATE mode. This reduces current consumption but increases the time to reconnect. Also, you should avoid any HIBERNATE period of less than 10 minutes on cellular devices.”
I understand it as the EN only really comes into play during a watchdog timeout which then pulls the EN pin low for 30 seconds. Not sure if I am understanding this right though? In any case, this external RTC/watchdog method seems like a better way to do it then the Deep reset tutorial.
That all said… looks like we gain a little but not too much between ultra low power sleep and Hibernate sleep. Per docs.particle.io:
“Since the difference in current consumption is so small between HIBERNATE and ULTRA_LOW_POWER, using ULTRA_LOW_POWER is a good alternative if you wish to wake based on time on Gen 3 devices. The difference is 106 uA vs. 127 uA on the Boron LTE, for example.” So for the purpose of this, I’d gain ~21 uA using this circuit over my current circuit.
Seems like the main advantage is maybe a more robust watchdog being external timer as well as saving 21 uA. Now the question for me… is it worth switching if I already have the PCB designed using the prior version.
Since @rickkas7 has published a new App Note on Watchdog Timers:
I thought it would be a good idea to adopt his design to replace the RTC and Watchdog elements of this design. This will simplify the board, align to Particle best practices and help improve the stability of the solution. I have respun the board and sent out for a few boards from OSHPark. Please take a look.
Of course it depends on your particular use case. In my example, I need something that will go into the field for about 3 years and work reliably. For that reason, I am going to respin my board to adopt the approach that is in the App Note. I think this will be the most supported approach that reflects Particle best practices. As always, I will share my results here.
Yeah agreed. Pretty sure I'll be making the switch. Sounds like this is what is in the tracker. Would you mind posting your updated Eagle Cad files to your GitHub repo as preliminary design or sharing separately? I'd like to review it in more detail and might save me some time. Thanks!
Agree. Great to finally have a platform recommended solution.
I have a PCB on the way with a TPL5010 as in the App note, but designed before that note came out.
AB1805 looks like an awesome chip. The minimal config solution in the App note, I will likely use later. Without having looked at the crystal yet, I wonder if could be ditched for transport devices, as they tend to break there.
With the complexity of the full solution I think the Tracker SOM is a great way to test that to the max.
I also updated my PCB design but used the watchdog circuit from that App note. I just ordered another set of PCBAs for my own PCB with this. Since I was making changes, I also added the cap chipmc used for future Solar charging capability. We will see how long the new PCBA takes to arrive. In the meantime as I wait, I’ll be updating my sketch.
Finally found out why the 30s power down is the only safe way (no reliable way to reset modem+OS consistent over several OS releases, as it is not directly exposed and keeps changing). So I have to dump the board I already sent off and put in the AB1805.
As discussed earlier in this thread, the TPL5010’s inability to be synchronized with the device’s sleep / wake cycle was an issue for me too. Also, bonus on the pin deprived Boron, you get the “Done” pin back since you “pet” via i2c.
Yes, I have found that while a power reset should be a last resort, it is often the only way to get back to the known good state.
@chipmc - Overall, really nice board layout and I appreciate you sharing! Something to consider for your carrier board layout would be to utilize the PCB real-estate directly underneath the Boron on the PCB. The bulk of the components are small and easily can fit within this “white space” on the PCB. I think it would reduce your costs quite a bit for PCBA if you can keep it single sided for SMT parts. For example, in a different board, I tried to fit most items directly underneath the PCB on the top side of the board and not have anything underneath.
Good point. Over time, the number of components on my carrier board has steadily gone down. I should take a look if, in the latest design, they will all fit on one side. Great suggestion
The good news is that my assembler, MacroFab, does not seem to charge a premium for having surface mount parts on both sides. Still, worth a look
Oh ok… yeah makes sense. I never priced out a 2 sided board before so wasn’t sure. How do you like MacroFab? I’ve been ordering from PCBWay and I’ve been happy so far. I’m coming in about $10-$15 per board (ordering 10 at a time) and roughly 3 weeks from placing the order to having them in hand. I’ve been soldering the headers and any other through hole components myself but everything else was assembled. I’m sure a lot of it is just personal preference. Mostly interested in the normal lead time from MacroFab. In the past I did OSH Park for PCB only and then PCBWay for assembled.
I wanted to put a pin in this thread as I think I am going to wrap up development of these boards as I think they generally meet my needs. Not sure what the next step is - perhaps the B-SOM? If so, I will kick off a new thread.
Here is where I ended up on this board. I have had MacroFab produce over 200 of them so far and they are working quite well. The main changes since this thread started:
Fantastic work @chipmc - very much appreciated in all the time you and the community put in to this. It helps us all! I’d be interested in a B-SOM version. I’m not an expert in PCB layout but happy to help in any way I can. I’ve been curious on when someone should transition from a Boron to B-SOM or what would drive someone to use a B-SOM over a Boron. If there is a specific # of devices or maybe functionality needed? As always, still lots for me to learn… but that’s what makes this fun right?
Very good question on the BSOM versus Boron. From my perspective, here are a few reasons:
Perhaps I want a more optimized power supply optimized for solar or using some other battery chemistry…
The BSOM packaging supports a lower-cost and more secure connection between the module and the carrier.
Ability to take advantage of European and NA modules with one carrier.
Unfortunately, it does not seem to be cost as my estimate is that the extra complexity of the carrier board would offset the small difference in cost between the Boron and the BSOM. That said, it is possible that enterprise customers with large orders could see a benefit.
Developing with BSOM, I would stay with Boron unless the 2G3GLTE combo outside US is needed. Or you expect it to take another 6-12 months before hitting the market, and are working with 1000+ unit orders.
The Boron has the external SIM option for those few spots where you really really need it, and a wider choice of OS versions, to find one that is working well with the features you are developing. Both have turned out to be very important.
To get extended coverage with the BSOM, you need an enterprise plan and additional per country negotiation and payments to get the extra carrier(s). I have not been able to get specific pricing without big orders, so no way to know what that would look like. A major disadvantage with BSOM.
I need to spend more time on these forums than I do I always find a few great nuggets like this on here.
