Mini Edition
UPDATE
The SoftRF Mini device described on this page was first introduced in 2020.
Today, in 2024, there is a new SoftRF Midi design available. It uses most recent hardware from the same Heltec brand. However, the design is way more advanced than the the previous one.
Below is a complete description of older SoftRF Mini design which is still available on the market.
- Compatibility
- Comparison with Dongle Edition
- Certificates
- Use cases
- Disclaimer
- Bill of materials
- Quick start
- Settings
- Enclosure
- Buttons
- LEDs
- Battery life
- Optional equipment
- Links
Mini Edition is a variant of SoftRF DIY GA proximity awareness device been implemented in a small, lightweight board form factor.
It is supposed to require minimal skills from a builder to begin with and gives an opportunity to evaluate if the SoftRF technology is appropriate for your needs.
The Mini is based upon third-party's hardware - Heltec Cubecell-GPS board, which is available for direct purchase from manufacturer at more or less reasonable price (20+ USD).
Cubecell-GPS is:
- a multipurpose ,
- DIY-friendly ,
- low power ,
- lightweight
- LoRaWAN GNSS assets tracker board.
The Cubecell-GPS is an example of cutting edge technology. It contains:
- Cypress PSoC4100S Low Power MCU ;
- Semtech SX1262 Long Range Low Power RF Transceiver ;
- Air530 (GK9501 based) or Air530Z (AT6558 based) Low Power GNSS (GPS/GLONASS/BD) Receiver module ;
- 0.96" 128x64 I2C OLED display
| Type | Protocol | FLARM | OGN tracker | PilotAware | Skytraxx | SoftRF |
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| Radio | FLARM AIR V6 |
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OGNTP |
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P3I |
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FANET+ |
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| Data | FLARM NMEA |
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| Garmin GDL90 |
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Dump1090 |
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1 - it is necessary for a reader to distinguish the difference between statement "compatible"
and statement "fully compatible".
SoftRF implements only a reasonable minimum of the protocols specs.
No "bells and whistles" so far.
Comparison with Dongle Edition
This is a picture of the Mini and Dongle, side by side:
"Pros" of the Dongle are:
- it typically comes with SoftRF firmware been factory pre-installed,
- has Type-A plug for direct connection into a PC, Mini-PC or tablet's USB slot and
- built-in SMA RF antenna connector
However, the Mini:
- is certified (by Heltec) to meet FCC and CE requirements,
- has micro-USB connector to supply power or/and data transfer, and
- built-in 0.96" 128x64 I2C OLED display, and
- push button with software defined function, and
- external Li-Po battery charging circuit
Mini is the second ( after Uni ) SoftRF Edition that uses RF design approved by appropriate government agencies.
Heltec CubeCell-GPS (HTCC-AB02S) has the following certificates :
- (EU) CE Certificate of compliance
- (US) FCC Verification of conformity
These approvals are typically applicable for:
- land use and
- with genuine factory firmware.
The Mini is a drop-in replacement for a wired GPS module that is typically used by e-Readers adapted for aviation purpose, such as Rakuten Kobo.
This is an illustration on how to wire a Kobo Mini with the Heltec CubeCell-GPS , e-Reader side:
From the CubeCell side: 2
2 - it is recommended to connect VDD with pin 7 of the CubeCell-GPS header (as shown on the picture above). This is a signal for the SoftRF firmware to make it's battery voltage monitor inactive.
For serial port pins mapping of other Kobo e-Reader variants, please, read the Get High, Stay High web page.
Connection settings: 38400, 8, N, 1
The Mini is also good to operate as a standalone, battery powered device - similar to most of other SoftRF Editions do.
The bare CubeCell board comes without any of built-in 2.4 GHz wireless interfaces nor pressure sensors. If you think you need these extensions - you may consider to solder a 'daughterboard' that will provide these features missing.
The BLE + Baro daughter board is attached to the back of the Mini unit.
Use the HM-10 datasheet to become familiar with and configure the BLE module prior to first use with the SoftRF Mini Edition.
An example of proper XCSoar Device assignment:
SoftRF firmware for Mini Edition is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
In general a lot of Chinese DIY electronics manufacturers are known to behave this way:
- sometimes they may not apply necessary Q.C. before releasing of a product from factory ;
- they may arbitrary change schematics and electronic components from one batch to the next one ;
- they may terminate manufacturing of a board just few months after initial production.
Author of SoftRF firmware:
- will reject any hardware related claims associated with Heltec CubeCell-GPS development kit. Ask for support from seller or manufacturer ;
- reserves the right to suspend or terminate support of Heltec CubeCell-GPS in the firmware at any time.
For the time being ( December '20 ) there were no critical hardware issues reported for current version of the CubeCell-GPS kit. However things my change over the time...
If you have issues with bringing up your new Heltec CubeCell-GPS or just not happy with the board - be prepared to execute your Purchase Protection plan.
| Number | Part | Qty | Picture | Source |
|---|---|---|---|---|
| 1 | Heltec CubeCell-GPS 3 |
1 | |
AliExpress 1 2 3 |
3 - 868 MHz variant is applicable for these world regions: EU, RU, NZ, SA, IN ;
915 MHz - US, CA, AU, KR, IL ;
433 MHz - CN .
| Number | Part | Qty | Picture | Source |
|---|---|---|---|---|
| 1 | SMA female to uFL adapter | 1 |  |
AliExpress |
The following parts are optional and could make sense for Autonomous device use case.
| Number | Part | Qty | Picture | Source |
|---|---|---|---|---|
| 1 | 602248 560mAh Li-Po battery with JST 1.25mm 2pin connector | 1 |  |
AliExpress |
| 2 | Bosch BMP280 pressure sensor | 1 |  |
AliExpress |
| 3 | HM-10 Bluetooth LE module | 1 |  |
TBD |
| 4 | SoftRF WebTop Serial | 1 |  |
AliExpress 1 2 3 4 5 |
Use these instructions to start operating with your delivered Mini board.
Procedure of settings change is very similar to that the Dongle Edition has.
Settings description is located there.
If you are an application developer and you think about to add the Mini configuration menu into your software, please, use:
- C/C++ header file and
- example of usage (in SkyWatch)
Decision was not to create a unique 3D design of enclosure for Embedded use case because there are plenty of Kobo cases available on the Thingiverse portal. Just use Kobo + case keywords for your search requests.
However, there is a SoftRF custom 3D design applicable for Autonomous device use case:
STL files of this enclosure are available. For details, please, read this page.
When unit is Off:
- press and release mode button to turn the unit On.
When unit is On:
- press and release mode button to scroll onto next OLED information page, or
- press and keep holding mode button for 2-3 seconds to turn the unit Off.
Green LED flashes when built-in GNSS module has proper satellites fix.
Orange LED indicates battery charging status and/or power supply over micro-USB port (when battery is not connected).
Current consumption from 3.7 Volt battery:
| Mode | Average current |
|---|---|
| Active | 56 mA |
| Sleep | 0.4 mA |
Operating time from a full charge depends on your actual battery capacity.
SkyView EZ is a DIY companion device for Mini Edition.
