I am working on a project to collect random records produced by RFID TAGS, save them with timestamp on an SD card, and be able to send the update of this data, i.e. the new data recorded on the card, once a day. The file created on the SD card contains only two columns, timestamp and tag ID. I have seen that for this type of functions it is recommended to use an HTTPS API, but I am not sure if this would really work. Can anyone guide me ?
Thanks !
If you’re looking for someone to write the code for you then you’ll probably be disappointed.
Your timestamp data will need to be in UNIX milliseconds format, and you could either use the HTTP(S) API or the regular Blynk library with the Blynk.beginGroup(timestamp) command.
I guess that my main questions would be around how you’re obtaining/maintaining the current system time for your readings, how you’re powering your system, how you’re connecting to Blynk, and the type of hardware you’re using - non of which you’ve included in the information you’ve provided so far.
Pete.
First of all, thank you very much for your quick response.
Sorry if I don’t express myself correctly, but I do not expect anyone to write the code, I’m only just looking for guidance to confirm that I am facing the project correctly
I have thought to use the Lilygo T-SIM7080G S3 board, equipped with an ESP32 and LTE connection, with an external RTC type DS3231
The device would usually be in sleep mode, waking up when presence is detected and opening a preconfigured log window. These logs would be stored, with their time stamp, on the SD card, and once a day the device would wake up and send the collected data to a database in BLYNK. The device would be powered by lithium batteries, and should have an autonomy of several months
I’m at your disposal to expand this information, if you consider it convenient
Thanks to the advanced for your collaboration,
Do you want to expand on this, and why you want to send the data once per day rather than immediately?
Pete.
It is about saving energy to achieve maximum autonomy, and for this reason the MCU would work most of the time in sleep mode, and would wake up only the necessary time to perform its functions. No real-time monitoring is needed, only collecting data periodically, and for this reason and in the line of saving energy, it would only be necessary to activate the LTE transmitter once a day
You haven’t said what sort of presence detection system you’re using, or how it will be triggered, and TBH it would be far better if you were more forthcoming with information rather than me having to drag information out of you.
I’d suggest that you start by doing som experiments with sending batched dummy data to Blynk via the HTTP(S) API and get that working, then decide how you’re going to synchronise your RTC with an external data source then use this to do your timestamps, and then develop the SD card read/write functionality along with some method of purging the data occasionally.
Moving forward, it would be better if you asked specific questions about aspects of your project, and of course provide much more data about where you are at, how/why you’ve reached tgat piint, and what exactly you’re having problems with.
Pete.
Hi Pete,
I will follow your advice Pete to face this project, and I will comment when I have more concrete doubts in its application
As I told you from the beginning, I just wanted to confirm if the best way to dump the data from an SD to Blynk was to use an HTTP API
Thank you for your cooperation, receive a cordial greeting,