RFM69 TX power testing & library fix

The RFM69 library has been very robust and stable over the years. It is widely used in many hobby and home automation projects as well as research and commercial products. But that doesn’t mean we can’t find occasional things to fix and improve!

Is there a problem?

Recently, after renewed attention to a long time issue relating to power levels being incorrectly set, I took measurements and found the setPowerLevel() function was behaving somewhat unexpected. Instead of a smooth  Namely it as making available the lowest possible transmit power levels on the HW/HCW (aka high power) variants of RFM69. Since a commit in 2015 the 32 power levels were actually made into 16 steps and only using PA1+PA2 in high power mode. Not so much a loss except for those hoping to maximize battery life by running at the lowest power levels on the HCW – in which case they’d be better off using the CW instead. But this is enough to find a fix and take full benefit anyway of what the HCW has to offer.

Basic TX power testing

To produce power profile I put together a set of Transmitter and Receiver examples. To measure power output you can just use the transmitter sketch – it toggles TX mode and you can navigate the power levels from min to max. Below is a simple hardware test setup that can be used to take some power measurements: a CurrentRanger reads the current going into a Moteino+RFM69HCW that radiates an unmodulated carrier signal into a dipole. Idle MCU current (TX off) is read and then subtracted from total current with TX enabled:

To also measure RSSI (poor man’s power meter) we can just use another Moteino with the receiver sketch mentioned above, which will simply sample RSSI continuously (in RX mode), at a max AGC setting of -48dB to simulate a long “distance” since we’re doing all this in close proximity (the same room!). Open the transmitter sketch in a serial terminal and toggle TX mode with t and increase power with + & - in steps or < & > in dB – there is a new function setPowerDBm() in RFM69 library v1.5.0, in addition to setPowerLevel(). The CurrentRanger will show the current drained by the Moteino when transmitting at different levels and the RSSI on the receiver will also reflect different output power levels.

This setup produced the following power profile on the W/CW radio, nothing unexpected since there’s only PA0 to be used with no other registers to set, power levels being set in RegPaLevel.OutputPower. The only thing to notice is the ‘step’ in TX current and RSSI which indicates something’s definitely being switched inside the transceiver itself as _powerLevel crosses the middle of the RegPaLevel.OutputPower register, even if PA settings remain unchanged (only PA0 is used).

On the HW/HCW, in v1.4.3 (prior to the fix this blog is about) the power profile looked like this:

As it turns out the startup power is correctly set to a valid level 31, but calling setPowerLevel() even once results in values being set from 0-16 (all “forbidden” – see tables below) and never back to the original 31. This results in a ‘step ladder’ of transmit power levels vs. current. I know this sounds confusing, because it is.

The theory – datasheets and registers

To better understand what’s really going on, first we need to clear some confusion and understand that RFM69 radios have several possible transmitter PA (power amplifier) combinations for different output power profiles as outlined in the datasheet:

For W/CW radios things are very simple – only PA0 is wired to RFIO output pin and it can produce from -18 to 13dBm, corresponding to 32 possible power levels that can be set in RegPaLevel, as clearly reflected in the W/CW graph above.

For RFM69 HW/HCW radios things get more complicated, there are two possible PAs  and a power boost mode to be enabled to reach the highest output of 18 to 20dBm, according to section 3.3.7:

I know of only one other good article that outlines all this in detail, a blog by Andre Hessling, I found it accurate and so my focus is not to replicate that here, but rather use it as reference and complement for those wanting to get a full picture, so check it out if you want to get more in depth.

So!  The RFM69 library v1.4.3 and prior, has been only using PA1+PA1 in boost mode, at power levels 0-16, except at startup where _powerLevel was initialized and set to 31 and never divided by 2 like in setPowerLevel() – bug!.  In addition, the datasheet says levels below 16 are off limits for the PA1+PA2 combination, but because this works it went unnoticed for a long time, at least in my library (semi bug?). If you’ve read Andre’s article, you will notice PA1 alone can be used and he proposes using the following PA combinations for HCW:

  • PA1 (and PA1 only!) from -2 to 13 dBm output
  • PA1+PA2 from 14 to 17dBm output
  • PA1+PA1+HighPower for 18 to 20dBm

If we revisit the datasheet, we realize there is actually a power profile overlap between these 3 combinations:

Notice for instance we can achieve -13dBm in 3 different ways on the HW/HCW:

  • using PA1 only with RegPaLevel.OutputPower=31
  • using PA1+PA2 with RegPaLevel.OutputPower=27
  • using PA1+PA2 with RegPaLevel.OutputPower=24

Enough already, what’s the conclusion?

Since theoretically the output is the same, it would be interesting to see the current profile against each of these as well. To cut this (really) short, I will link the spreadsheet with my tests and graphs and just mention the final conclusions. It matters which PA combination you pick, as a general rule, using more than one PA will result in higher current for the same effective transmitted output, at first this seemed counter intuitive but that’s what the meter and RSSI shows. I determined the best combination for HW/HCW to be the following:

If you notice, there are now only 24 _powerLevel‘s with slight overlaps between steps 14,15 and 16,17. The light orange band PA1+PA2 combination is sandwiched between PA1 and PA1+PA2+HighPower and helps optimize current used at those theoretical dBm outputs. This is similar but a little different than Andre’s proposed bands – I suspect he may have looked at RSSI but not at current used. Overall this produced the smoothest output power vs. RSSI vs. current curves that I could determine – with minimal ‘step’ jumps on the current and RSSI, and this is what we’d expect to properly use the power levels, especially in the RFM69_ATC extension which automatically regulates the power level based on a desired RSSI. And here are the measurements in a graph:

For the W/CW nothing really changes since there was no real issue, the graph will be the same as the first one included in this article.

Update the library and test on your own!

I made a new release v.1.5.0 which should address all these issues and includes the TX power testing examples which can be used by anyone with perhaps different/better test setups to verify these findings. Please update  and try this out. I may update this blog with further info if need be in the future since it’s more of a reference for RFM69 PA modes.

CurrentRanger updates

Thanks to MGX3D there are now some nice improvements to the CurrentRanger:

  • Firmware updates and optimizations, battery icon instead of text (faster drawing)
  • Improved sampling speed
  • Smarter Auto-Off – avoids turning off when sampling via USB
  • more menu items and options
  • Fusion360 models now available, see this page for links

There is also a new improved OLED enclosure model designed by MGX3D as well. This is also available to pick up in the webshop or you can print your own – models available here and here.

There is now also a python based graphic visualization GUI designed by MGX3D and available here on Github, check out its features and specs on Github, mainly it brings the ability to view serial data from the CR in logarithmic scale and also in autoranging mode, w00t! Here’s a preview of that GUI available for Windows/Linux (and MacOS planned):

A word on using the CurrentRanger

It seems some folks are too excited to try it out and miss reading some of the guidelines on proper usage, this is really important not to overlook. I have seen a few strange cases of abused units that were returned. It turns out it’s never a DOA condition or anything related to a real fault. All units are tested, calibrated, turned ON/OFF etc, to ensure they are functional. Faults are usually a case of improper use, improper soldering or attaching of headers and terminals which cause damage to SMD components, the OLED, etc. Here’s an example of how to not solder the OLED header, or at least not how to leave the board after a solder job, this will cause all kinds of problems (corrosion, possible leaks and faults on the board):


Finally, I would like to express my gratitude for the feedback and positive response and interest into CurrentRanger. When used properly with love and care, it is an amazingly versatile and ultra-portable tool that will work for many years without any trouble. There are plans to make it even better and constructive feedback is always welcome and encouraged. Don’t forget that WELECTRON Germany is now our official distributor in Europe and carries the CurrentRanger as well as many other products.

DDM Novastar L-BF-12 Feeder upgrade

Over the past year or so I spent a lot of time designing and iterating over a new upgrade for my pick & place. The result is an upgrade kit that can be installed without modifying the original feeder. It enables the bank feeders in my DDM Novastar LE40-V to no longer have to peel back the cover tapes. That alone is a huge benefit. Watch this video of this upgrade in action, and see what other benefits this new concept brings to the L-BF-12 bank feeder.

MoteinoM0 R2 released

MoteinoM0 is now at revision R2. Here’s a summary of changes:

  • removed castellations for the short side header, to allow better panelization and better routed side finish on the long sides. The castellations remain on the long sides.
  • the micro USB connector is slightly recessed, the front being about flush with the board edge
  • changed top silkscreen “VUSB” header pin to “Vin”
  • “Serial” changed to “Serial0” which corresponds to the board definition Serial0. Note: the main Serial is the USB serial and SerialUSB has been deprecated.
  • added “VBat” header hole on the upper header, next to “Vin”, this was a popular demand to allow connecting a battery through a header or feed the JST connected battery to external devices. More details in this forum thread.
  • minor other layout optimizations and trace thickness adjustments

Available now in the shop. Note that MoteinoM0 along with other Moteinos and boards are now also available from Welectron Germany, check it out if you’re in the EU, it’s a good time to shop from there rather than wait for months for the crippled regular mail service.

New OTA GUI v2.0 released

If you’ve been using Wirelessly Programming, a unique feature that comes with all Moteinos, you will love this new update to the OTA GUI. The main requirement for this release was the ability to change the Programmer Moteino settings right from the GUI without reprogramming through the Arduino IDE. Here is the summary of changes:

  • A few UI changes and improvements and a new settings section:

  • support for on-the-fly change of Programmer RF settings: networkIDnodeIDfrequency (in Hz), EncryptionKey (either blank for no encryption, or 16-character key), BitRate (either default or 300KBPS). Existing RF Settings can also be read from the OTA Programmer.
    Note: for the settings feature to work, the latest OTA Programmer sketch is required
  • UI no longer locks during transfer!  The GUI window can be moved/minimized, log can be cleared at any time
  • ability to CANCEL a transfer
  • ability to refresh the COM ports dropdown
  • updated instructions
  • backward compatible with older programmer/target code
  • various bugs fixes and improvements

When you change settings on the Programmer, for the OTA transfer to work, those same settings need to match on the Target (sample starter Target code here), or the target has no way to intercept any packets from the Programmer.

If you’d like to change the RF settings on the Target, then first compile the sketch with the new settings into a HEX file, transfer it as you’d normally do, then change the settings on the Programmer via this new GUI, and you’re ready to do more OTA transfers once settings match.

The ability to change to 300KBPS instantly is very useful. That makes transfers significantly faster:

As always, if you run into any issues, have suggestions or bugs to report, please don’t hesitate reach out or start a discussion in the forum.

Happy Moteino OTA-ing!

MoteinoMEGA based Data Logger

Ed Mallon runs the Cave Pearl Project which is all about “developing a data logging platform from inexpensive pre-made breakout boards, and are using this at the heart of new environmental sensors that anyone can build.” Ed is also a contributor in the forum, and has posted a great in-depth tutorial that steps through making a submersible data logger. From the blog’s own summary:

In this tutorial, a logger is built using a 3.3v Moteino MEGA with a 1284p CPU @ 16Mhz, w 4K eeprom,16K SRAM for variables & 128K program space. Considerably more than the 328’s 1K eeprom, 2K ram & 32K progmem. Also has a spare serial port for GPS/NEMA sensors.

MoteinoMEGA based Cave Pearl in ‘Prototyping Trim’ with I2C OLED screen & ADS1115 ADC. INT1 & Aref jumpered. The built also includes an RTC backed up by a coin cell.


It’s great to see Moteinos being put to serious work in such interesting and niche projects. While a custom PCB could be built to reduce the amount of wiring and make for a more compact logger/breakout solution, this tutorial is targeted and perfect for those who want to learn the skill of building data loggers or similar projects using off the shelf components. Thanks Ed and the Cave Pearl Project!

Gateway v9.1 release

The Pi Gateway software package is continuing to be improved and the latest release is v9.1.0 (see GitHub releases). It contains some breaking changes, new features, and bug fixes. This blog entry serves as a feature review, change log and update guide.

Breaking & potentially breaking changes

  • the NGINX site configuration file is now renamed to gateway instead of default and so are the references to its log files (gateway.access.log and gateway.error.log located in /var/log/nxinx)
  • settings: there is a new interface section that contains a new responsive setting. The uiTitle setting is moved to this section. See below for responsive details.
  • metrics completely reorganized as detailed below

Metrics modules restructured

The metrics.js file is now renamed to core.js and moved into a new metrics folder. Also, all the prior default mote definitions are removed from this file and broken into individual metrics files that contain all the functionality pertaining to that particular mote. They are now called metric modules. You will see a new metrics/_LowPowerLab folder containing all these default metrics modules which used to be all bundled in the former metrics.js file. The userMetrics folder is removed and any examples or other sample metrics modules are moved under the new metrics folder.

Metrics modules loading order

In addition to the metrics reorganization into modules, the main app will load everything in the metrics folder in a specific order as follows:

  • core.js module first – required
  • any other metrics module files in the metrics folder in alphabetical order (case insensitive)
  • any metric modules in metrics/subfolders (1 level deep only) in alphabetical order (both folder and file order – case insensitive)

Globalized metric modules functions & variables

Given the powerful modularity of nodeJS, we can share functions and (string, numeric) variables between metric modules. To define a global variable or function you simply have to define it with the exports prefix, example from core.js:

exports.ONEDAY = 86400000;

exports.isNumeric =  function(n) {
  return !isNaN(parseFloat(n)) && isFinite(n); //http://stackoverflow.com/questions/18082/validate-decimal-numbers-in-javascript-isnumeric/1830844#1830844

So now ONEDAY and isNumeric() can be called across the entire application, anywhere. If you wish to make a function local (available only to that metric module) then omit the exports prefix – examples can be seen in the RadioThermostat_CT50.js  module.

Here is a sample of how the app loading the metric modules, along with their globalized members.

The loading order affects overriding of any definitions/variables/functions defined with the same names.
[04-16-20 09:39:31.274] [INFO]   *********************************************************************
[04-16-20 09:39:31.293] [INFO]   ************************* GATEWAY APP START *************************
[04-16-20 09:39:31.296] [INFO]   *********************************************************************
[04-16-20 09:39:31.302] [INFO]   LOADING METRICS MODULE [./metrics/core.js]
[04-16-20 09:39:31.307] [LOG]    |- GLOBALIZING ONEDAY
[04-16-20 09:39:31.308] [LOG]    |- GLOBALIZING isNumeric()
[04-16-20 09:39:31.309] [LOG]    |- GLOBALIZING isValidIP()
[04-16-20 09:39:31.310] [LOG]    |- GLOBALIZING isValidNodeId()
[04-16-20 09:39:31.311] [LOG]    |- GLOBALIZING determineValue()
[04-16-20 09:39:31.312] [LOG]    |- GLOBALIZING determineGraphValue()
[04-16-20 09:39:31.313] [LOG]    |- GLOBALIZING timeoutOffset()
[04-16-20 09:39:31.313] [LOG]    |- GLOBALIZING millisToFutureDate()
[04-16-20 09:39:31.314] [LOG]    |- GLOBALIZING nextSunriseOrSunset()
[04-16-20 09:39:31.330] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/doorbellmote.js]
[04-16-20 09:39:31.340] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/garagemote.js]
[04-16-20 09:39:31.351] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/motionmote.js]
[04-16-20 09:39:31.363] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/RadioThermostat_CT50.js]
[04-16-20 09:39:31.386] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/sonarmote.js]
[04-16-20 09:39:31.396] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/sprinklers.js]
[04-16-20 09:39:31.412] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/switchmote.js]
[04-16-20 09:39:31.446] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/watermeter.js]
[04-16-20 09:39:31.455] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/_LowPowerLab/weathershield.js]
[04-16-20 09:39:31.466] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/examples/_example.js]
[04-16-20 09:39:31.478] [LOG]    |- GLOBALIZING ONEDAYHOURS
[04-16-20 09:39:31.479] [LOG]    |- GLOBALIZING secondsInOneDay()
[04-16-20 09:39:31.483] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/examples/_garage-auto-close.js]
[04-16-20 09:39:31.492] [INFO]   LOADING METRICS MODULE [/home/pi/gateway/metrics/examples/_InternetSpeedTest.js]

Given these major changes, you should rewrite/break any custom metrics in their own definition files following the patterns shown in the default LowPowerLab metrics.

UI changes

New Menu buttons & app info

You can now do a Pi reboot and shutdown straight from the app menu. There is a bunch of additional information shown – versioning, RF gateway information such as frequency and uptime (if available). The main page node list header is removed, and the Show Hidden button now shows how many nodes are hidden in that list (the button toggles their visibility as before).

Metric pinning affects order on dashboard

As requested in this forum thread, the metrics will appear in the node bubble in the order they were pinned. If you unpin+pin a metric, it will become the first in the node’s info bubble.

Responsive UI

The new interface.responsive setting (boolean) determines if the UI becomes a responsive grid when it is viewed on large screens (thresholds are 768px, 1020px).

Log/Terminal & debug messages

A few significant changes happened on the terminal page to make this UI more useful and readable:

  • there is a new “Simulation” set of fields that allows simulating a node message just as if it came from the actual node (through the RF gateway’s serial port)
  • the terminal button is removed on the terminal and settings page – the terminal input fields are now always visible
  • instead of serialized JSON, serial messages from the RF gateway are now pasted in plain text and prepended with the serial port’s name
  • simulated serial messages (such as from this UI or from non-RF nodes like the CT50-Thermostat), the logs are marked as such with (simulated)
  • pressing ENTER in these fields will trigger the Send or Simulate
  • if you want to log debug messages from your RF gateway in this UI, you can simply prefix those messages with DEBUG: and all such messages are sent to all client UI terminal logs as well as in the permanent ~/gateway/logs/gateway.sys.log file (metric matching is skipped on these special DEBUG:something to log  messages). There is also a debug:heyNodeLogThisValue metric (in core.js among other special metrics) which allows you to send a debugging value from an end node, this is treated just like any other metric and is stored along with the other node’s metrics.
  • some special gateway requests can be made to the RF gateway (if it is coded to respond to them like the new PiGateway and MightyHat examples): BEEP, UPTIME, SYSFREQ, FREERAM, ENCRYPTIONKEY

Node Requests

A new experimental feature allowing you to send pending requests to nodes is available. This is a key:value pair that can be sent to a node to ask it to do something – like change a variable like transmission period, change behavior etc. There is a new button [+REQUEST] on the node details page. You can queue requests and the gateway will send them back to nodes in ACKs as they contact the gateway. This feature will require the new PiGateway or MightyHat examples which were updated and also improved with serial buffering. Your node then needs the ability to process all such requests and ACK them back to the RF gateway which in turn will ACK them to the app itself and mark that request as complete. Node requests can also fail, expire, be edited (ie updated with some new value), and repeated.

There are some special commands that the new sketches will process WRT the new node requests feature. You can see the request queue by typing REQUESTQUEUE in the terminal, the new sketches will respond with their content (or VOID if empty). You may also do things like manually VOID a certain request to a certain node (ex. 123:VOID:REQUEST), or void all requests to that node (ex. 123:VOID).

Miscellaneous other changes

  • license is now CC-BY-NC-SA-4.0
  • latest NGINX, PHP7, nodeJS/npm packages, along with app node modules updated
  • settings page Save and Cancel buttons removed – changes are now applied upon leaving the settings page
  • graphs show 1 day of graph data (vs. 8 hours previously)
  • changing the serial port baud setting automatically switches the port to the new baud without the need of restarting the application
  • npm-request replaced with native node http module – this is to handle any http requests (like for the CT50 Thermostat)
  • Fail2ban optionally installed during setup. There is a guide page that goes into some detail about adding this post install or on prior versions.
  • various setup script fixes & updates as well as:
    • ability to install last stable version or latest unreleased code
    • added symlinks to webserver access/error logs in the ~/gateway/logs directory
  • new default icons are generated at 300px to make them look better on the larger responsive grid, the icons_template.cdr is also updated
  • dashboard MENU button hidden if there is no socket connection
  • dropped PiBakery

Updating from an older version

Before you plan to try the upgrade make sure to:

  • copy-backup existing database, settings, any uploaded images and metrics files
  • backup your entire existing SD card

While it’s possible to do an in-place update, the changes are so extensive that it will take a long time to document everything and every file/script/permission that changed, and it’s very likely I or you will miss something. I recommend doing a clean install, on a new (good time to upgrade to a newer faster) SD card, then copy your old data. To do this, follow the setup guide on this page. Once everything is running and you see the gateway app run, you will need to sudo systemctl stop gateway to stop the app from running. Then copy over all your data files, images, merge old settings into the new settings.json5 file, and add any custom metrics you may have had into the new metrics folder – ensure they are formatted after the same pattern of other default files.

Current Ranger R3mk4 – new firmware & optimizations

The CurrentRanger continues to be improved especially on the firmware side, and in some hardware aspects as well. This blog is to summarize the most important changes and bug fixes with this new release:

  • UF2 bootloader – allows easy backing up of existing firmware and swapping with new firmware via a simple drag-drop action (like copying to/from a flash drive). More details and links to new firmware are given in the guide firmware page.
  • faster boot time!
  • faster ADC sampling (for auto-ranging and for USB/serial logging)
  • more linear and improved resolution ADC readings with secondary mid-range ADC reference (when this reference is active a ½ symbol is shown in the upper left corner. This reference is automatically switched for upper-range readings or when switching ranges
  • calibration information no longer printed on the product label, instead it is briefly displayed on the OLED after power-on and also output on the USB serial port. Unfortunately the EEPROM in the SAMD21 is not persistent between firmware updates, and hence you should always save this calibration information in case you plan to update the firmware.
  • Auto-off warning is now blinked on the OLED in addition to the buzzer sound. Also, the Auto-Off function timer is reset either by manual touching any pads, or by range switched when auto-ranging is enabled (previously reset only by manual touch of any pad)
  • There is now a set of commands available through the USB serial port. This allows to easily change parameters such as the calibration values, toggle logging via USB, toggle Auto-Off function. You could basically add more commands if you customize the firmware. Here are the defaults and examples of executed commands and their output:
  • Some limited number of CR3mk4 units have shipped with firmware that will always show 4.95Vbat. Use the latest firmware to correct that.
  • Better 3D printed enclosures – thanks to a brand new Prusa MK3S printer
  • Silkscreen changes: The previous “Load-” label at the input black terminal changed to “DUT+” to make it more obvious that this is not a “negative” terminal but is the positive side of the DUT. See header photo.

There are 2 essential calibration parameters: gain and LDO voltage. The LDO voltage can always be measured on any GND and 3V exposed headers. The gain has to be adjusted either with the recommended value or during measurement of a known accurate load (ex: apply the a fixed load and increase/decrease gain until the OLED reading reflects the given load). Note that the LDO voltage can slightly change based on factors such as temperature, load (ex: with/without OLED), whether charging is taking place, battery voltage. Each LDO is unique, has its own output voltage and will respond differently. If the LDO voltage swings a lot then you might need to adjust the values before a measurement to obtain the most accurate OLED/logged ADC readings.

A few continued challenges in manufacturing…

Some components like the thumb terminal (Phoenix Contact, made in Slovakia) and banana terminals (chinese) have long lead times. Right now the thumb terminal was on backorder for a month from Mouser and they just updated the lead time to an additional month. A simple component can disrupt the supply chain,  thanks to the chinese virus putting a pause to everything.

As you might have noted, PCBs and components have been hard and slow to source due to the world apocalypse we’re living through. It takes much longer to manufacture PCBs with all the pledges from the chinese makers that everything is back to “full production”.

One of the most painfully inconsistent features of chinese PCBs is the silkscreen, like most other things chinese it sucks. Look at OSHPark silkscreen, next to a chinese made PCB, any. There is no measure of comparison (and not just silkscreen). With the large graphic features on the front side of the PCB, any silkscreen quality glitches become obvious. Thankfully functionality is not affected by silkscreen, and unfortunately the magnitudes in cost difference forces PCB manufacturing to be done mostly in china. I doubt anyone else would pay $5 extra for perfect silkscreen, I certainly would only because I am quite OCD about things I use and look at on a regular basis.

The power button is hand soldered to each unit, and liquid flux is used in the process. Flux residue is removed with flux cleaner. Sometimes traces of dissolved flux may be  absorbed inside the button. At first, while this dissolved flux is still liquid, this is not a problem and the button works fine. When the flux solidifies, it can act as a film on the button internal dome, causing intermittent contact or in rare cases an apparent complete loss of contact. The most effective fix is to add a drop of flux cleaner or IPA to the button, press the button multiple times, in an effort to dissolve and loosen up any flux traces inside the button, and also absorb this solution back with a q-tip.

That’s it for now, any other minor changes will be documented in the CR guide.

MightyHat R4

I ran out of MightyHat stocks a few months ago and was debating whether it is time for a complete remake with a SAMD chip. While that feature set slowly baked in and out of my brain people kept bugging me to make more. Ok, it’s finally back in stock and basically a miracle I even managed to get PCBs delivered after several weeks of delays.

Although functionally and firmware wise R4 works the same as the previous revision, I made some changes, the most noticeable:

  • circuit layout optimizations especially for power distribution and the booster
  • removed dual HCW/HW radio layout, only HCW is now supported
  • charger is set for 500mA

The R4 schematic is in the MightyHat guide. Sorry but I will not stock any more Nokia5110 LCDs, too many quality issues to worth the hassle. You can find them cheap on the web if you’d like one on your MightyHat. A future revision will support OLEDs or some other nicer screens. There are actually Nokia5110 pin equivalent TFTs if you look around you might find some. Also, the SD1306 OLEDs can also be found in SPI variants so you could use those instead of the Nokia5110 with the MightyHat R4.

PS. Dear corona virus, maybe US made PCBs and affordable don’t go in the same sentence but, wouldn’t it be a great time for someone to come up with a US based PCB service that is high quality to compete with china’s hits and misses? Or maybe since you’re made in china you won’t last long anyway and the question will be forgotten once again. Oh well!

Moteino SAMD 1.5.0 release

There is a major new release for the Moteino SAMD Boards Package 1.5.0. It will popup as an update reminder the next time you restart Arduino IDE, or you can go to the Boards Manager and update from there:

Here are the most significant changes in the SAMD package:

  • All MoteinoM0 and CurrentRanger boards will start shipping with the UF2 bootloader (it’s well worth a read if you’re not familiar with it). The TLDR; is: it supports sam-ba serial protocol uploads as before (via CDC serial, from bossac or via the Arduino IDE) and it also supports drag-drop updates of the firmware as well as the bootloader itself (via a MSC flash drive that appears when the M0 is running the bootloader). Extremely useful if you want to allow an end user to update the firmware and/or bootloader with a newFirmware.uf2 file drag-drop to the “flash-drive” simulated by the bootloader, without the need for the IDE. You could enter the UF2 with a RST double-tap as before, and you’d see a new “flash-drive” on your system (the CURRENT.UF2 is the actual firmware loaded in the MCU – useful to back up before an update):
  • To top off the UF2 awesomeness, MoteinoM0’s will continue to support updates of the firmware from the external FLASH-MEM chip, after an OTA upload via RFM69. The latest RFM69 library release 1.4 has been updated to support this.
  • SerialUSB is now completely removed from the MoteinoM0 and CurrentRanger variant definitions:
    • On MoteinoM0 Serial is now the USB serial, Serial0 is the UART on pins 30/31, and Serial1 is the UART on pins 0/1.
    • On CurrentRanger Serial is now the USB serial.
    • SERIAL_PORT_USBVIRTUAL is now Serial by default
  • You might notice in the MoteinoM0/CurrentRanger boards menu, there are now some options like choosing the USB stack (Arduino, TinyUSB) and more notably the Crystal selection. You can compile for the external crystal (default for MoteinoM0 R1) and “crystal-less” ie. the internal ultra low power 32.768kHz clock). When running without the external crystal, the internal clock is tuned using the USB bus clock which is very precise.

Note that the Moteino AVR boards package is now at v1.6.1. You are encouraged to update both of these packages. Older boards running the sam-ba bootloader may be flashed with the new bootloader included in the 1.5.0 package via SWD programmer. I may even offer to do this for free if you’re willing to return the board and pay for shipping back to you. Please report any bugs or issues in the MoteinoM0 or CurrentRanger forums.