Is there a way to save voltage data directly (without a microcontroller) to anywhere, like EEPROM, SDCARD, etc.?
For example, I am using an MPX pressure sensor which gives 0V to 5V analog output. Instead of converting voltages to pressure in a microcontroller and saving (which takes time, money, space, etc...), first, I want to save analog data, then taking these data to my computer for the conversion of voltages to pressure.
You can't use a EEPROM or any other storage means that is digital without first converting your signal to digital. Using a microcontroller is the obvious and simple way to do that.
However, if you really want to satisfy your inner cave man, acquire one of these:
This stores analog data from a few 10s of Hz to a few kHz. You'll have to consult some clay tablets to learn how to use it.
One problem you will have is that the frequency of interest is probably lower than what it can record. The solution is to have your signal drive a voltage-variable oscillator, then record the output of that oscillator. In other words, FM-modulate your low-frequency signal.
There are ICs that implement the voltage-controlled oscillator function, but that would way too sensible and clash with your retro goal. Get a few of these:
and make your own.
After the data has been stored, you "rewind" (see clay tablets) the storage medium. Then "play" it into a PC sound card. The PC finds the frequency of the signal, from that converts back to the voltage, and from that determines the actual data value.
Or, you could just use a microcontroller and consume less time, money, power and space.
No, you can't store an analog value as-is on a digital storage medium like an eeprom or an SD card.
You could do an analog-to-digital conversion (using an appropriate chip) to convert your analog to digital. For the next step, writing to an SD-card practically requires a processor. If you really don't want to use an MCU you would end up designing and building one yourself from simpler building blocks. That is an interesting educational project, about 0.5 man-year for a student who is good in both programming and electronics.
An EEPROM will be a bit easier to write the values, but reading the values to your PC would be more complicated. In the balance it would still be much easier than the DIY MCU, but still quite a project.
When you look around you everyone uses MCU's for almost all projects, including data logging like you want. Guess why!
What you are trying to do sounds like logging.
There are lots of data loggers out there sold commercially. If you want to log voltage readings you can try googling "voltage logger". Such devices write a log file to a storage device (sd card, thumb drive etc.) from sensor readings.
Technically this uses an MCU internally. But you never see the MCU, you never have to develop software for the MCU and you never touch the MCU.
The answer depends on your definition of "directly".
I could imagine the following setup (far from "direct", but without an MCU):
Target memory:
Alternatively the whole setup above could be implemented in an CPLD or FPGA, not an MCU.
You could also use a Motorola MC14500B controller, which is not an MCU.
In practice, today, the cheapest, smallest, fastest and most reliable option is an MCU.
Since you consider using a computer to "convert voltages into pressure", you need to use the data format that is understandable by computers - which is a digital format. Therefore something must convert the analog output of your sensors into digital form first, "digitize" the voltage. Thus there must be an Analog-to-Digital Converter in between. Converting the digitized voltage into pressure readings (using maybe some tables or conversion formulas if the conversion is nonlinear) is a good task for your PC.
Technically you don't need a MCU to perform this conversion, a dedicated FPGA with hardwired algorithms can control all data sampling and communications. But MCU is more convenient, especially if it already has an ADC built in.
And you don't need to spend your time on building MCU+converter, there are devices called "data acquisition systems" (DAS), or "data loggers" that will do it for you, sample/convert analog data, and communicate them via convenient interface as USB (or RS232). Some DMMs have this data acquisition capability, or you can get a dedicated DAS from places like DATAQ.com. The DAS would come with all necessary data logging software, and you can store the data anyway you wish, SD, or else. Understandably the conversion from your sensor to usable pressure data will cost you some money, nothing comes for free.
Yes, you can... sort of. Look for ISD chips, designed for dead simple and cheap applications, where you need to record and replay analog signals. Used in talking toys, musical postcards, and the like. I doubt they are accurate enough for your purpose, though.
http://www.nuvoton.com/hq/products/isd-voice-ics/isd-chipcorder-family/?__locale=en
Since your only requirement is not using uC, you can use USB-SPI bridge to interface a SPI ADC with PC.
That's the cheapest solution if you don't want to use uC.
Or your can fund $$$ for institutes, research centers,... so they can speed up the research of analog memory, the thing you need right now.
0~32V voltage data logger USB-503
stores 32k measurements
with intervals from 1 s to 12 h.
Stores on USB dongle with battery enclosed.
Easy export to Excel.
Inc Software at www.mccdaq.com
Cheap.
It's only 2.1 million Rials
ehm.. make that 2.2m and rising
