M5Stack LoRa Range Issues

Investigating 32u4 to M5Stack LoRa poor range issues; Background information & initial tool setup.

Well, after my last post regarding the fascinating world of FPGA programming, I really thought this next post would continue on that topic. I really want to try out Luke's tiny FPGA board. Alas I've encountered another issue on a project that warrants sharing and someplace for me to keep my notes.

TL;DR

• Misc details and notes on LoRa
• VisualMicro ESP32 USB Debugging caused by new driver version
• NESDR issue with SDR software and driver install
• LoRa Range issue still unresolved, stay tuned for part 2

Late last year, I finally decided to buy a couple of "DIYmall LoRa32u4 LORA RA-02 Module Development Board Long Range Communication 1KM LiPo Atmega328 SX1278 with IPEX Antenna for Arduino" devices when Amazon had one of their "Lightening Deal of the Day" sales. Not to be confused with LoRaWAN - these are simple serial-type broadcast devices but with very long range. Getting them to talk to each other was ridiculously easy mainly thanks to the great Adafruit Feather 32u4 with LoRa Radio Module tutorial and sample code.

Perhaps there's some software to do LoRaWAN with these (if anyone knows, let me know ) - however I don't have any service providers nearby and the gateways are expensive.

edit 2/18/18: here's a video on creating a LoRa gateway:

By the time my LoRa modules arrived, I had forgotten the title explicitly called out the "RA-02 Module". In hindsight, I'm surprised the Adafruit code worked at all, given their description naming their LoRa device as a Adafruit Feather 32u4 LoRa (RFM9x).  Apparently the RA-02 and RF95 libraries are "close enough" - as my 32u4 appears to have the exact same RA-02 module as used on the M5Stack LoRa module. (I wonder what, exactly is on the Adafruit device?)

Which reminds me: be sure to check the frequency of the respective LoRa devices: they need to match not only each other, but also be allowed in respective county of use!

  (source: RF Wireless World)

After having the proof of concept working with the two 32u4 devices (RadioHead RFM95 libraries)  - which I was able to show them working hundreds of meters apart through very obstructed signal path and certainly not a straight line-of-site (e.g. hill, buildings, trees, etc)... I thought it would be cool to have a display module on one end, controlling the GPIO's on the other.

Some time ago, I had ordered an ESP32-based M5Stack so I decided to use this for a "console" along with their LoRa Module to talk to a very remote 32u4. Seems simple enough in concept, eh? Ha! Nothing is ever as easy as is is supposed to be.

First, the M5Stack core library uses different Sandeep Mistry LoRa drivers. (see also github) Thinking that "LoRa is LoRa", I assumed that they would work together. Indeed the workbench test was a complete success the first time.

However, the first real field test was a disaster. Taking the dog for a walk with an M5Stack connected to USB battery pack in hand, I expected to be tweeting success far from home. I was barely out of WiFi range across the street when the M5Stack stopped receiving messages from the 32u4. Certainly a long way from kilometer LONG Range.

As it turns out, KongDuino recently left a rather interesting blog review of the M5Stack and LoRa modules. It would seem that I'm not the only one with LoRa range problems. If it was easy, it wouldn't be any fun - right?

Note that the 32u4 devices use so little power, that the Anker portable power supply turns off after a few minutes - perhaps thinking nothing is actually connected. Perhaps a USB hub or something might help for a road trip with it.

I've posted my code on GitHub under a project called LoRa-GPIO. This is a pitiful hack of sample code, but an otherwise operational proof of concept of the 32u4 transmitting a signal for the M5Stack to receive and display.

So to investigate the range issues, we'll need some tools such as break-point debugging and signal analysis.

Note for anyone using VisualMicro for development (like me). If any problems are encountered debugging the ESP32, be sure to check the CP210x USB driver version - particularly just after Windows Updates. There's apparently a known problem with recent drivers not working, Simply select (or install as needed) an older version to fix:

Ok, so anytime there's a signal transmission issue at hand, it is helpful to have some visualization tools. I have the inexpensive Nooelec Smart SDR on hand.

See Using SDR Sharp Quick Start Guide. Download Windows SDR Package from https://airspy.com/download/  Need to disable new security feature that prohibits unsigned drivers.

bcdedit /set testsigning on

Reboot. To turn off:

bcdedit /set testsigning off

Even running zadig as administrator, I was unable to change drivers. So ok, I guess I needed to download new driver installer from the Nooelec Getting Started.  Windows is brutal; it completely removed the prior SDR drivers I had installed and working. Grr,,,

SDR Sharp had complained about the Visual Studio 2015 C++ runtime not being able to be installed (I have Visual Studio 2017 installed)... so rather than fuss with that, I installed the CubicSDR 0.2.2 software also located at the bottom of the Nooelec Getting Started with NESDR page.

Note there's an entire CubicSDR web site, and the most recent version appears to be v0.2.3 released in January of this year (2018) complete with source code on GitHub.

Once finally installed, the LoRa signal can be visualized:

So, ok.. I've fussed with Visual Studio debugging, SDR software install, and typing up all these notes and most of the day has flown by. No progress today on the actual problem of poor LoRa range. Clearly a part two is due and coming soon...

• VisualMicro IDE for Visual Studio
• M5Stack.com
• M5Stack LoRa Module on AliExpress
• DIYmall LoRa32u4 LORA RA-02 SX1278 for Arduino
• Adafruit Feather 32u4 with LoRa Radio Module
• Arduino 433Mhz Lora SX1278 Module DRF1278F on tindie
• 433MHz LoRa SX1278 long range RF wireless module DRF1278F For Arduino on ebay
• Semtech SX1272/3/6/7/8 LoRa Designer's Guide
• https://github.com/sandeepmistry/arduino-LoRa
• https://github.com/m5stack/M5Stack
• http://www.electrodragon.com/w/SX1278
• https://github.com/gojimmypi/LoRa-GPIO
• Sparkfun Serial Peripheral Interface (SPI) tutorial
• M5Stack Custom Fonts sample
• https://github.com/espressif/arduino-esp32/issues/821
• CP210x USB to UART Bridge VCP Drivers
• Semtech - What is LoRa
• SDR Software

First FPGA Test Drive with Altera Cyclone IV

I decided to finally learn how to program an FPGA! Here are some first impressions and notes to self for future reference.

TL;DR

• Blaster drivers need to be manually installed from C:\intelFPGA_lite\17.1\quartus\drivers
• Cyclone IV board is EP4CE6E22C8; do not use default "auto device" (for Pin Planner) 
• Verilog file added manually, module name must match file name and is case sensitive
• Source files in the project are "Design Entities"
• Do not insert to remove the USB Blaster ribbon cable while the device is powered on.
• Download vendor board files here
• JTAG programming of FPGA is temporary and lost upon power cycle

I ordered my first FPGA board - the Altera Cyclone IV EP4CE6 FPGA Development Kit and USB Blaster from the Numon Electric Cyberport Store on Aliexpress thanks to inspiration by Amitesh. He did all the footwork to find what seems to be the coolest Cyclone FPGA board that can still be programmed with the free version software. (note the really cool GX version with Nios processor needs software costing thousands of dollars)

If you order the board from Numon Electric, they have a download available on one-drive that includes a ton of really great documentation, sample code, and more. The file is called "RZ301 EP4CE6 development board.zip" however the contents of that zip file consist of mainly a single file "Altera Cyclone IV board V3.0.rar". Windows users will be annoyed that there's no native tool to easily extract RAR files. Having a linux VM or WSL will be handy here. The latest version of winzip also appears to now support RAR extraction.

Overall I was quite happy with the responsive customer service, prompt delivery, and quality of my new FPGA board. If you look close at the picture of my board, the actual silkscreen quality is much better than shown: the blur is from the poor picture.

While awaiting delivery of my Cyclone, I found this other tiny, inexpensive FPGA created by Luke Valenty. Note that if you order on the tinyfpga store web site, you can pay with Amazon, without having the hassle of creating an account, etc. This board is so cool, I think I will have a separate blog about it later.

Surprisingly, my Cyclone board arrived relatively quickly in only about 2 weeks! (the estimate at order time was 19 to 39 days)

In order to program the Cyclone board, the Altera Quartus Prime Lite software is needed. Unlike some other programs, installation was quick and easy.

IMPORTANT: Do not insert to remove the USB Blaster ribbon cable while the device is powered on. There was an included warning that the board would likely be damaged. I did not test this.

The USB Blaster was not Plug-N-Play, and Quartus Prime did not see it:

A quick google search indicated that the drivers need to be manually installed; instructions copied from Altera site here for reference:

The Altera On-Board USB-Blaster II cable appears as Altera USB-Blaster (unconfigured) when first attached to your system. After it has been configured by the Quartus Prime software, it will appear as Altera USB-Blaster II (JTAG interface) and then Altera USB-Blaster II (SystemConsole interface). You might need to install drivers for each of these interfaces; follow the steps below to install the drivers.

You must have system administration (Administrator) privileges to install the USB-Blaster and USB-Blaster II download cable driver.

Driver Installation for Altera USB-Blaster

1. Plug the USB-Blaster download cable into your PC. The Found New Hardware dialog box appears.
2. Select Locate and install driver software (recommended).
3. Select Don't search online.
4. When you are prompted to Insert the disc that came with your USB-Blaster, select I don’t have the disc. Show me other options.
5. Select Browse my computer for driver software (advanced) when you see the Windows couldn’t find driver software for your device dialog box.
6. Click Browse, and browse to the <Path to Quartus Prime installation>\drivers\usb-blaster directory.
   • Note: Do not select the x32 or x64 directories.
7. Click OK.
8. Select the Include subfolders option, and click Next.
9. If you are prompted Windows can’t verify the publisher of this driver software, select Install this driver software anyway in the Window Security dialog box. The installation wizard guides you through the installation process.
10. When The software for this device has been successfully installed dialog box appears, click Close.
11. To complete your installation, set up programming hardware in the Quartus Prime software.

Driver Installation for Altera USB-Blaster II

1. Plug the USB-Blaster II cable into your PC.
2. Open the Device Manager, and right-click on the Unknown device under the Other devices branch.
3. Select Update Driver Software.
4. Select Browse my computer for driver software.
5. Enter the location of the Quartus Prime software USB-Blaster II driver files directory (<Path to Quartus Prime installation>\drivers\usb-blaster-ii) in the Search for driver software in this location field.
6. Click Next.
7. Click Install in the Would you like to install this device software? Windows security dialog box.
8. Close the Update Driver Software - Altera USB-Blaster II (Unconfigured) successful installation notification. The Device Manager now shows a new branch called JTAG cables with an Altera USB-Blaster II (Unconfigured) node.
9. Open the Quartus Prime Programmer. Within a few seconds, the JTAG cables branch displays two nodes: Altera USB-Blaster II (JTAG interface) and Altera-USB Blaster II (System Console interface).

The pin-out of the USB Blaster cable is such that it can be used for three different programming modes: AS, PS and JTAG, as shown in this pin definition table from the Intel FPGA USB Download Cable User Guide:

The important thing to note here is that programming via JTAG is temporary! My board came pre-programmed with something that cycles though the 4 LED's on the board. There's always a little fear of sending a new program that toasts your new FPGA (yes, this is absolutely possible!). So it is cool that upon power cycle, the original config is loaded back into the FPGA to confirm all us well. Fortunately my first program actually worked the very first time!

As with all development environments, Quartus has its own annoyances. I found it very difficult to simply: File - Create New Project and get something to actually work without a bit of fussing.

The first annoyance is the default directory. For example, in Visual Studio, the IDE is smart enough to know to actually create a directory for your project. Any you only need to type it once. Here, the default directory is the IDE, and projects are created there unless explicitly stated in THREE places. So the new Project Wizard starts here:

Be sure to append a project name to the directory:

Or better yet, I keep all my project in c:\workspace\ in this case for the new myFPGAgizmo project:

You can set the default location in: Tools - Options - General - Default File Location.

I created an empty project...

and did not add any design files...

This next step is important... the default device is set to "Auto". What this does is completely disables the Pin Planner feature needed later, giving an error:

Cannot display Pin Planner the current Compiler settings assign an AUTO device.

For a newbie like me.. the solution was not very obvious. To avoid this, change the default at new project time to EP4CE6E22C8

The tools are left as default:

On the final Project Wizard page, the summary is shown:

Tada! All done, right? Nope. The "Wizard" still does not actually complete a project.

Double-click on "myFPGAgizmo" to edit the code, and a nice, less-than-intuitive error pops up:

Can't find design entity "myFPGAgizmo".

Not exactly to most intuitive error message for a newbie. 

Good luck finding "Add Design Entity" in the menu. Here, you just need to know that a new Design File needs to be manually added (why the wizard does not do this, I do not know).

So from what I can tell:  a source "File" == "Design Entity".

File - New - Verilog HDL File:

Quartus does not give you an opportunity to name this file when it is first created. Only at save time will it prompt to give it a new name. Visual Studio users will not be impressed.

Now another important note: The name of the module MUST MATCH the name of the "top level" file name, and it is case sensitive. The "top level design entity" is that file first listed. You just need to know this. Otherwise the Quartus software gives the less-than-intuitive error message:

Top level design entity "myFPGAgizmo" is undefined 

Here the "myFPGAgimoName" needs to be the same as the file name "myFPGAgizmo":

So after dealing with those annoyances the learning curve, I was finally able to write some Verilog that I found in another tutorial (see page 14):

module myFPGAgizmo (x1, x2, f); 
  input x1, x2; 
  output f; 
  assign f = (x1 & ~x2)|(~x1 & x2); 
endmodule 

This is where things get interesting. It is one thing to write some code, but getting it to interface to the real world is what makes it fun! Normally I/O is abstracted through complex device drivers and API calls. However, it does not get much more direct in FPGA programming, as the actual pins on the chip are assigned to variables in our code! Even better, there's no bizarre renumbering that I find ridiculously frustrating in the world of Arduino programming. There's a single pin number. Ahhh. What bliss.

As can be seen in the schematic, Pin 87 is LED4, and Pins 88 and 89 are tied to keys (button switches) KEY1 and KEY2 (but yes, instead labeled S1 and S2 on the board). Yes, those are the actual pins numbers on the Cyclone IV - pins 87, 88, and 89. No big deal, right? Well, sure - but apparently not all engineers agree. Just google "pin numbering arduino" to see how many hours have been lost to frustrating abstracted re-numbering.

Once code is entered, it is compiled using the menu: Processing - Start Compilation. When the pins are not actually assigned, there will be a compiler warning:

Critical Warning (169085): No exact pin location assignment(s) for 3 pins of 3 total pins. For the list of pins please refer to the I/O Assignment Warnings table in the fitter report.

Click on Assignments - Pin Planner. (recall above, we explicitly assigned our chip part number, otherwise this feature is not available).  If you double-click in the Location column, a drop-down list will appear:

We need to assign the pins to keys and LED as shown in the schematic:

Simply close the Pin Planner and compile again. We're ready to send the FPGA code to our device!

Note the USB Blaster connection in the very first picture on this page.

Click Tools - Programmer. If the currently selected hardware says "No Hardware", click the "Hardware Setup" button (make sure your device is plugged inn, and drivers installed)....

In this case, I selected the USB Blaster by double-clicking on it.

To send the FPGA code to the device, select "Processing - Start" (or simply press the "Start Button"). If successful, there will be an indication in the progress box:

That's it! There's now an XOR gate programmed in the FPGA. Press S1 or S2 to have the LED got out. Press both or leave both unpressed and the LED1 will be illuminated. Cool.

Note we've programmed the FPGA via the JTAG connector on the board. When the board is power cycled, we'll lose these changes and the board will revert back to vendor ship default.


Note that if you find cheap Cyclone boards on flea bay, the most recent version of Quartus does NOT support the older chips! I sadly learned this after buying a cheap, bare-bones Cyclone II and then noticed it was not listed as a device option in the Quartus IDE. The latest version supporting the Cyclone II is Quartus version 13.0sp1 from 2013. (I wonder if side-by-side installs are supported? I didn't try)

Here's a chart of supported devices vs Quartus versions specifically the Cyclone series:

That's it for now... send me a message on twitter if you have any feedback / suggestions / notice any typos.


Resources, Inspiration, Credits, and Other Links:

• Altera - My First FPGA Design Tutorial 
• Quartus Prime Introduction Using verilog Designs
• UDemy - Learn VHDL and FPGA Development
• UDemy - FPGA Turbo Series - Implementing a UART
• Verilog HDL support for VSCode
• Verilog Tutorials and Examples at nandland
• Altera Cyclone IV from Numon Electronic Cyberport Store
• Resource file with documentation and samples
• Intel FPGA USB Download Cable User Guide
• Quartus Prime Download
• Altera Device Downloads
• Gnarly Grey UPDuino v1.0 Board
• A Look at TinyFPGA Boards
• UART, Serial Port, RS-232 Interface Code in both VHDL and Verilog for FPGA Implementation
• Altera-Lime Connectivity and DUC/DDC Design Example