openchirp | Craig Hesling

Easybits Serialization Service

Sun, 03 Dec 2017 07:46:59 -0500

Summary

Easybits is an on-the-fly Google protobuf stream decoder/encoder for OpenChirp. This service is one of the core services that an embedded device may need in it’s OpenChirp data pipeline.

The idea is that your device would use Google Protobufs to serialize (and deserialize) it’s data and sends it to OpenChirp. The Easybits service is then invoked, which deserializes your data and publishes human readable values back to OpenChirp.

Easybits just needs the user to describe what protobuf types were declared and where to place the data.

How it works

Google Protobufs are great for creating compact serialized data packets for typical sensor values.

Protobufs requires you to create a .proto file that describes what data you intend to send back and forth. It then compiles this .proto file into a set of language specific interface files, which containing functions and objects to represent and aggregate your data.

Here is an example .proto file description for a smart light bulb.

// SmartBulb.proto
syntax = "proto3";
message LightStatus {
 bool status = 1;
 int64 intensity = 2;
}

Due to this native language integration, protobufs are easy for end users to pack up and send data messages, but it is non-trivial to create long running services that can interpret all possible custom protobuf messages, without recompilation.

To get around the Protobuf constraint of recompiling for every new protobuf message, Easybits uses dproto to adapt to new user described messages, without even restarting.

Links

Easybits on Github

OpenChirp

Sun, 03 Dec 2017 07:46:59 -0500

Summary

We are creating a community-driven low-power wireless connectivity solution for IoT.

My Contributions

Designed, built, and installed outdoor gateways
Created custom Debian packages for gateway software and configuration - ocgw
Created gateway system monitoring service - SysMonitor Device
Created the Golang framework for Users, Devices, and Services - framework and Example Service
Created the LoRaWAN integration service
Created data serialization/deserialization services - ByteTranslator Service and Easybits Service
Created prototype trigger service - Trigger Service
Designed and built ultra low-power LoRaWAN client devices - The LoRaBug
Created the hardware abstraction layer and adapted the necessary firmware stacks for the LoRaBug - LoRaBug Software
Created serial bootloader tool to flash the LoRaBug over micro USB - ccbootutil

Checkout the OpenChirp.io Website

The GridBallast Controller

Sun, 03 Dec 2017 07:46:59 -0500

FIXME - Add the gallery line back here.

Summary

This is a modular demand response controller for household or commercial appliances that tend to consume a lot of power. The original goal was to intelligently control water heaters.

Water heaters tax the power grid heavily during peek times (morning and afternoon), when people are using the most hot water. These spikes in power consumption require power providers to plan ahead and preemptively start up temporary power plant that may not meet the typical efficiency and cleanliness standards.

Fortunately, water heaters store enough hot water for most normal household tasks, including taking a shower. Whether they turn on during your morning shower or not, makes no noticeable difference. Unfortunately, hot water heaters are controlled by mechanical switches that activate the water heaters when the internal water temperature drops below a certain point. This causes the heaters to activate during events like your shower in the morning, when it might not be necessary. If the water heater was to delay it’s activation to some random time during the middle of the day, we could alleviate this peak demand issue. This controller is designed to monitor the water heater vitals, observe it’s usage patterns, and intelligently control it’s activation.

Schematic and Board

The Controller

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The CTA2045 Adapter

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Simulation

This board required some custom analog design. I simulated some of the more complex circuits in LTspice. The circuits and simulation are shown on the GitHub Simulations Page.

System Monitor Device (for OpenChirp)

Mon, 06 Nov 2017 00:00:00 +0000

Summary

How it works

Links

sysmonitor-device on Github

The LoRaBug

Sat, 03 Dec 2016 07:46:59 -0500

Summary

The LoRaBug is a general purpose low-power sensor platform. It tightly integrates an ARM Cortex M3 based MCU, BLE, and a LoRa radio.

Checkout the Github repository for more detail.

Key Features

TI CC2650 MCU/Transciever - ARM Cortex M3, Bluetooth+BLE, and 2.4GHz 802.15.4
Semtech SX1276 radio - 137MHz to 1020MHz supporting LoRa, FSK, GFSK, MSK, GMSK, and OOK
Micro USB - Bootloading and Console
Onboard 500mA 3.3V regulator

Software

I have adapted the HAL of the official LoRaWAN stack for the CC2650 with TI-RTOS - LoRaWAN MAC
A spinoff from my example firmware can be found - LoRaBug_Firmware.
I have created a cross-platform serial bootloader tool that allows you to flash the LoRaBug using just a micro usb cable - ccbootutil

Schematic and Board

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