Hello there. As mentioned in the title, I would like to make a multi-channel Datalogger.
But before I start, I would like to get some input on its feasibility as well as alternatives.
I am hoping for the end result to have the following capabilities.
-Be able to log data from x10 tri-axis accelerometers via I2C (actual goal is x40) at a 1000Hz
-create a timestamp at the beginning and at the end of each measurement
-Send the data to my computer via usb or bluetooth and display it (also allowing for marking of the plot)
-Store the data on an SD card.
I thought of two ways to do it.
The first one is using an adafruit Feather M0 adalogger with an SD card and connect it to the devices directly. However, I think the delay between the devices may be to great and I would have to offset
the recorded data based on their time delay. Also, I do not know how much time it will take to write
to the SD card at such a high rate. I considered using multiple buses with, for example, a teensy board however, I don’t know if that is such a good Idea.
My second idea was to use one attiny 84 per channel, which are connected to one sensor and 2x eeprom storage devices. It will read the data, fill the first storage and switch to the second storage after it has been filled. This could be scaled to , for example, 10 channels each consisting of 1x attiny84 1x sensor and 2x eeprom storage devices. To keep it synchronous, the acquisition process is initiated via externally controlled interrupts.
When the attiny84 switches, another micro-controller dumps the data of the even numbered eeproms onto an SD card. To prevent the arduinos from interfering with each other, the I2C bus connecting them to the eeprom device will be disconnected via Mosfets (Open/CLose in pairs) or bus buffer. In addition, one channel is reserved for creating annotations by writing the respective note at a given index to mark when a new setting is tested.
I realize that this potentially creates new bottlenecks with the secondary micro-controller but I can’t think of any other way. I would very much appreciate your input on this.