rxd

Operation: cstand ;)

I’ve a little girl…who has some rubber teats which helps she sleeping thru the whole night. But…the best of these devices must be charged prior to usage - lately i’ve spend about 30-60 seconds charging them; but I’ve got an idea to create a “charging station” - from a sheet of paper by using some cad magic. The plan was to create a maimed pyramid - to get some stability; because the top hole should has about ~25mm diameter.

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Original plan: create schemantic I’ve met with one of my friend who does have degree in Electrical Engineering ;) And i’ve wanted to ask him to check my circuits…he asked for schemantics - and because the only “real” existing schemantic was already built… I’ve looked for a schemantic drawing tool before - but I’ve failed to find the right one for me. I was very fortunate that I’ve subscribe to ForceTronics on youtube earlier (he makes very good videos in home automation topics…gives a very good presentation about what he is talking about), and I’ve got a notification that he have just published a video about EasyEDA - i’ve considered easyeda before; but around that time it looked a bit too complicated.

Kitchen devices finetuning & overall experience

I’ve forgot to write about this…so I try to write my memories before I forgot this ;) Day 0 I’ve placed all devices and cables where they should be…check that it works and unpluged it for the night. Day 1 In the morining I’ve showed it to my wife: that it’s now working ;) I’ve showed my wife the most important thing of the new kitchen lightning system… there is only one plug where it gets all the electricity…in case something is not right (catches fire…or gives wierd noises) she should be able to neutralize it without having to track down the cables - and I’ve encouraged she to do so If she thinks its needed.

Fix&deploy devices in the kitchen

I was able to disable the nrf autoack feature; it is strange why I have to enable autoack prior to disabling it….but it looks like these modules like it this way ;) I’ve noticed a weak soldering in the sensor device - i’ve tried to fix it (without soldering) ; it went well enough to finish the current measurement for sizing the fuse; but its another minor showstopper ;) Next day or so I’ve added a diode and a 200mA polyfuse to the led driver board; to create some protecton for these circuits.

Working OTA fw upgrades!

Lately i’ve finished the ota related software components…its still ugly; but at least it now uploads & swaps the new firmware with a success rate of around ~90%…sometimes the mega messes something up; and avrdude timeouts…but its fine for me for now at least. There were a very strange problem…sometimes the otad behaved strangely or just seemingly lost contact with the mega….it took for me a while to realize that i might be facing some memory issues; fixing all valgrind errors and warnings uncovered that i’ve forgot to initialize a buffer offset variable…I should definetly turn on -Werror and its friends…

Remote fw loading

I’ve already evaluated what i would really need to protect my comms from 3rd parties; but i still miss the stream alike controllers on both ends to maintain the channels between the devices. remote writing (arduino – arduino) With the local self writing capability ready for use, i started adding some sequence based retrasmission capable stuff (i wasnt sure where i will end up with it eventually)… After creating the prototype for a single one directional channel I was surprised that the encryption part will just fit into the playfield by adding it behind the seq handler later on.

OTA capable bootloader for arduino

Earlier i’ve found the optiboot project, which looked like a great candidate to reshape into the key instrument to enable remote firmware upgrades for the pro minis. The idea is to have the flash split logicaally in two: first section running the current firmware second section is reserved for the new firmware The bootloader is the only “trusted” part of the flash from within flash write commands are accepted.

Kitchen2 - boxing

Moving the existing breadboard application to a soldered one was easier than before…the hardest was to find a suitable timeframe when I can start working on it. drilling holes I’ve ordered a small box earlier(and was hanging around without any purpose); because I don’t really had strict size contrains or ergonomical requirements for it - I decided to use it. I decided to use 3 dc jacks to connect:

Kitchen2 breadboard prototype

During the last week I was able to build the breadboard version of the kitchen2 device. Learning from my previous problems with just partially prototyping the circuit. I’ve built it fully …i’ve connected the “production” power supply to it and the ledstrip too. The led strip is dimmed by a fet…because this was new for me I’ve consulted with some experts on the arduino irc channel about what i want to build and they have taught me the simplest cases of using Fets:

Control layer

I’ve been struggling with it for days now…maybe if I write it down, it gets a clearer picture for me too ;) So…I will have multiple devices with the ability to communicate to each-other via radio. Possible challenges/problems: the system itself should be able to withstand partial crash of the infrastructure…so in case of catastrophic failure; all functioning parts should sustain their function as much as possible. this means that the control logic will be distributed and the nodes should behave in a mesh network like manner it might be possible that the RF24 modules would need multiple hops to reach the target this might not be the case, I will check this fact later - having a real mesh network is cool, but in case I dont need it at all… unauthorized 3rdparties should not interfere with the operation of the system communication protocol must be resilient to replay attacks I can’t do anything to prevent an adversary to flood the radio channels with noise… the nrf’s design is very limited…1 channel out; 5 channel in.