Oops. I answered the other one but at least the TS is getting consistent answers.It is hard to fathom how this device could be compatible with a low power environment. You can ignore the power dissipation figure under Absolute Maximum Ratings, since that power level will destroy the device. You have two power supplies with two different voltage levels and different power requirements. The two together require 920 mW. That is what you should design for.
Physical size: I’ll like it as small as possible (I don’t have an answer here since the solar panel takes a lot of space).I know this is not necessarily what you want to hear, but if you want to maximize your chances of success, please take this seriously.
I think your process is upside down. You really need to create a list of requirements and then specify the components. You might have to change the specs as you find what is and what is not possible, but choosing the radios before deciding what they need to do is not going to end well.
Some things to consider:
What is your monetary budget? Unless it is open ended, you will have to make tradeoffs n specifying components. If you have only an informal idea of the budget you are likely to
What is the nature and capacity of your “solar harvesting”? This will determine things like:
- Physical size of the completed device
- Location
- Maintenance
- Cost, of course
What is your time budget? This will decide things like:
- The possibility of saving money by building yourself instead of buying
- Alternatively the necessity of buying to save the time of building
- The importance of parts availability and delivery dates
What kind of power budget will you have with that setup? This will determine things like:
- Hours of operation
- Data rate
- Transmission frequency (interval, not radio frequency)
- Practical distance from base
But before all of this, you need to draw some pictures (block diagrams, high level network diagrams) and write a narrative about how you expect the system to behave.
Start with stating the problem you are trying to solve. This is critical. You have to clearly articulate what success will look like. If the system “works” what problem will have been solved?
Then sketch out a general description of the solution. You can and should include how user interaction will work if there is any. Stories about what it will be like to use it are best, they help identify missed problems and requirements.
You don’t have to do this excessively formally but you have to have some idea of the moving parts because as you can see if you consider the list, they all interact and creating a requirements list is an iterative exercise in prioritization and optimization.
After you have some version of this done, you can choose a radio, and power equipment, and a hardware/software platform for processing. I will be happy to help you with that if you have a reasonably orderly and complete requirements list. Otherwise, it’s all guessing.
Hi and sorry to bother you again! I'm set up for the most hardware part. I have a 5.9V/304mW/61mA solar cell (it's pretty small and has a weight of only 25g) that goes into a solar battery charger with MPPT (found it very cheap for like 5 euros so I said why not, I only need to change a SMD resistor to change the max charging current) that outputs 4.2V so I can charge a 1000mAh LiPo battery (the battery will be charging at a rate of 0.06C). Also I'll use 2 Schottky diodes and a p channel power MOSFET on the output to power the PIC+sensors+LoRa and to charge the battery (simultaneously) when I have enough power from the solar panel (when the sun is up and shining). The battery will go then into a fixed 3V voltage regulator (Low drop-out regulator that has a very low quiescent current). Now the thing is I need to use SPI communication (I know how to do that) with LoRa, and for compatibility between PIC and LoRa I need at least 128 kB flash memory and 8 kB RAM on the PIC part. I found PIC18f27Q43 that meets this requirements and uses nanoWatt XLP technology so I can consume even less power using deep sleep mode. The problem is that I don't find PIC18f27Q43 in mikroC to write the code and compile the hex file so I can load it into the MCU and also I don't find a compiler in MPLAB (I found the PIC, but not a compiler for it), do you have any other suggestion on what and how to program the PIC18f27Q43? As sensors I'll use an accelerometer, humidity +temperature sensor and a battery monitoring circuit. I'll send this information to a RPI 4 that I'll program as a data server with a web interface so I can save and visualize data and when certain parameters exceed a threshold value the RPI 4 will send a SMS to some phone numbers (eg: battery is critically low or the target is moving South, North, East, West and the acceleration and maybe a GPS module so I can get the position aswell but I might exceed the power budget and it's pretty hard to do).OK, so I am going to suggest a couple of things to start. Since your budget is reasonably large and it is a two node network, consider LoRa as the the radio/protocol. It is designed for low power operation, it has all the facilities to manage error detection and correction, and it can be expanded to many more nodes very easily. There are even public satellites that support it.
The second thing is that you watch a few videos from Andreas Spiess, whose LoRa and low power content is excellent. It will get you into a position to start asking specific questions and filling in the block diagram with actual parts for implementation.
Here is one of his videos to get started, but if you check his channel you will find many relevant topics.
There are specially designed indoor and outdoor solar cells from Panasonic, I chose an outdoor panel that will work outdoor, the requirement list for the project doesn't say it should be indoor or outdoor. The indoor ones doesn't go past 250 uW so I have to use an array of cells if I would want to power the circuit and they would occupy way too much space, same with RF harvesting (I designed a G Shaped Cuff Button Antenna that's omnidirectional and has dual resonance band to harvest the RF energy, but it provides like 1- 0.x uW so it's no use) because LoRa consumes 16-25 mW of power when it is in Tx mode. Also, even if the sensors are indoor, I can find a way to put the panel outside and the circuit inside. I didn't graduate my bachelor's yet so I don't need to reinvent things, it's only about the learning process and doing something that can be of use in some situations.Is the rating of your solar panel in full sun? You said it would be indoors, which means the solar panel might produce only a few percent of its rated power.
Bob
by Robert Keim
by Jake Hertz
by Jake Hertz
by Jake Hertz