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LoRa Irrigation System |
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====================== |
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This project is to build an irrigation system from LoRa capable |
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microcontrollers. The [Heltec Node151](https://heltec.org/project/lora-node-151/) |
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was chosen due to it's small size and inexpensive cost. |
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Design Decisions |
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---------------- |
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While investigating this, the LoraWAN protocol was investigated, but |
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after looking at the code complexity and other operational requirements, |
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if was decided that for this project, it was safer to target a direct |
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Node to Node style communication system. This would allow the |
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implementation to be more simple, and security to be built in. It |
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could also be used for other projects that need security. |
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One of the other requirements is that the code be 100% open sourced, |
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not GPL licensed, and no propietary components. This ment that using |
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IDE's like ST's STM32CubeIDE which is only available in binary form |
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was not a choice, as that would preclude building on an operating |
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system other than Windows/MaxOS/Linux. |
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Building |
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-------- |
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The build system uses the BSD flavor of make. This is the default |
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make on the BSDs, originally called pmake, but also available as bsdmake |
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for MacOSX, and likely other operating systems as well. |
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It also depends upon ARM's [GNU Arm Embedded |
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Toolchain](https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm) |
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which uses gcc as the compiler. It would be good to get it to |
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cross-compile with clang as well, but that requires finding a libc like |
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the nano libc that `nano.specs` in the above toolchain provides. |
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Once ARM's toolchain is in your path, the following should work: |
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``` |
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export MAKEOBJDIR=build |
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mkdir $MAKEOBJDIR |
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bsdmake all |
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``` |
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And in the directory `build`, a file `lora.irr.elf` should be pressent. |
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Flashing |
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-------- |
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Flashing can be done via the open source tool |
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[OpenOCD](https://sourceforge.net/projects/openocd/). For this, I use |
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a Digilent HS1 JTAG programmer utilizing the [resistor |
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hack](https://github.com/ntfreak/openocd/blob/master/tcl/interface/ftdi/swd-resistor-hack.cfg) |
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to allow an FTDI JTAG programmer to control the bi-directional `SWIO` |
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pin. |
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One caveat w/ MacOSX, is that it may be necessary to unload the kext |
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`com.apple.driver.AppleUSBFTDI` via the command: |
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``` |
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sudo kextunload -b com.apple.driver.AppleUSBFTDI |
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``` |
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as OpenOCD wants direct access to the FTDI driver. |
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Once that happens, the device can be programmed using the following |
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command: |
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``` |
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sudo openocd -f interface/ftdi/digilent-hs1.cfg -f interface/ftdi/swd-resistor-hack.cfg -f target/stm32l1.cfg -c "init" -c "reset init" -c "program build/lora.irr.elf verify reset exit" |
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``` |
