Datalogging - Page 1
Forum section: electronics / beginners

author: sidereal
author_rank: Contributor
timestamp: July 21, 2023, 01:54:57 pm
content: HelloI am looking for a simple datalogging IC. I want to log digital data, basically when a signal crosses a threshhold, it will be a 1, otherwise 0.The IC should havesome way (e.g. using a voltage divider and a xtal) to set its polling frequency,some way to set the threshholdsome way to decide which side of the threshhold is a 1(i.e whether signal voltage being more than the threshhold is 1 or the otherway round)some way to receive N ( where N is between 64 and 128) similar signal from similar, but distinct sources - i guess shift registers could be used in a cunning way to do thatsome way to save this data in a 4 or 8 kB Flash Memory, for k last polling events. Each segment of the memory corresponding to a particular polling event should include informaiton from each of the N sources, and there should be a way to specify i in {0,N}, j in {0,k} to recover the signal corresponding to the i-th source as it were during the j-th polling event.some way to recover and send all the data stored in this memory to an MCU (arduino or ESP)Everything i look up in google uses an MCU for this task. I would like either a dedicated IC or a circuit with discreet components.So my questions areWhich IC should I look for?How diificult would it be to do this in discreet components only , in case such an ICdoes not exist.Thank you.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 21, 2023, 02:06:59 pm
content: I don't know any IC (other than an MCU) to fit the request. You can use a handful of ICs to build such a device, but that would be very cumbersome. An MCU can do all that and more.Any cheap Arduino board ($3-$5) can do data logging. Arduino IDE (the programming tools) happens to have a few examples in it, including a few ready made programs for data logging, so it's a matter of a few mouse clicks to load the MCU with the example data logging program.My advice would be to use an MCU (an Arduino at first), then ask in the forum for the steps that you can't untangle alone.

author: sidereal
author_rank: Contributor
timestamp: July 21, 2023, 03:53:24 pm
content: I can do this with an MCU, no issue. But i was thinking about optimizing it even more. dropping the MCU completelyBut thank you for the reply

author: Siwastaja
author_rank: Super Contributor
timestamp: July 22, 2023, 09:40:28 am
content: No way there would be a fixed functionality chip for such complex and specialized use. Do it with an MCU and you get exactly what you need.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: July 22, 2023, 07:42:03 pm
content: $0.50 for an ATtiny is about as optimal as it can get. You won't have much memory so you need to send your data to something else.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 22, 2023, 10:17:06 pm
content: You can also put it in an FPGA.As an exercise you can draw a schematic with TTL IC's for a part of your idea. Drawing it in TTL for a parallel eeprom is doable, doing this for an I2C EEprom ... I wish you lots of luck.Then you'll realize that using an uC is the optimised solution.Personally I dislike the ATTinies vehemently. Annoying incompatibilities with the ATMega's (so you have to rewrite your own already debugged libraries again). Using a chip that has "just enough pins" is also the wrong part of optimisation. Just use a chip you're familiar with and get it done. Development time is probably a much more important factor.There is also an "openlog" project. From what I remember it's a postage stamp sized PCB with an atmega328 on the front and a a uSD card holder on the back side.