Simple logger

Maybe yet another logger. And maybe I am using old school components. For me this project is for learning and it will be the contributions of the people who give me feedback and me the person who will try to implement the feedback. I hope we can make it work ;-)I have something working but I want to buffer the GPS string in an EEPROM and flush it to MMC at some periods of time.

I have something working but I want to buffer the GPS string in an EEPROM and flush it to MMC at some periods of time.

This schematic I still do not have working...

I am trying something different. This solution is freezed.

Project Elements

20120928-195746.jpg (JPG, 896.02 KB)

schematic1.jpg (JPG, 260.28 KB)

microchip_bvdv.zip (ZIP)

18F46K22 element Eagle 6

simplelogger.zip (ZIP)

Proteus 8 file + MMC file + Hex (till now) PCB follows

Discussion (3 comments)

BMWTouring 11 years ago

The chip I am using is a 18F46k22....I could write the GPS to Flash RAM....and then flush it to MMC?

BMWTouring 11 years ago

I am connecting a 24C02C. but it looks like the performance is slow with large strings.

1 Comment(s)

ClemensValens 11 years ago

Hi BMWTouring,

If you want good help, please specify exactly what you want to do. We cannot read your mind.

From what I saw in the other contribution and comment, here are some suggestions. You are not obliged to read all the data coming from the GPS at 5 Hz. You can set a timer or used a timed loop to read incoming data only every 10 seconds or so (or whatever rate you are looking for) and ignore the rest. Then you can write it directly to the memory card. You would probably store the data first in RAM as complete sentences before writing it to the card.

Regards,

Clemens

BMWTouring 11 years ago

I have signals which I want to monitor at 200Hz. So I need to set the timer on 200Hz (?) And every 10Hz I can "grab" the GPS signal?? Also I want a I2C temp sensor on the chip. But I on the SDA and SCLK ports there is also an LCD screen (because I like it ;-) ). How can I master this?

1 Comment(s)

z80a 11 years ago

Hi,

I don’t think it is a good idea to buffer your data in an EEPROM, as it will get worn. You should better buffer your data in SRAM.

What kind of help do you request?

Cheers.

ClemensValens 9 years ago

One million cycles at 1 Hz is only 11.5 days. For a device that is on only occasionally that is probably fine, but for something that is always on I wouldn't recommend it unless you take a big one and make sure that you use it completely. A nicer solution would be FRAM. This is like a mix of RAM and EEPROM: unlimited cycles (100 trillion...) and powerless data retention so no battery required. Made by Fujitsu, Cypress and TI (since they bought Ramtron) you can get it easily now from Farnell for instance. 256 KBit available at 5 euros. Storing your data differentially (you are probably not going that fast & far) will give you lots of storage space. Regards, Clemens

BMWTouring 9 years ago

It has been a while, but I am going to try something different. With the ESP8266.

BMWTouring 11 years ago

My thoughts ;-) But the SRAM is also nice...the power must be on all the time. Not only for keeping the data alive..

BMWTouring 11 years ago

Nice! SPI SRAM... My target is for hobby racing with my motor. And the honest reason is, that I would find it booming if I could make an application like this ;-)

Hooligan0 11 years ago

Depending of the retention time you need, a small battery can be added to save SRAM. For example, a 23LC1024 [1] (1MBit Microchip SRAM) is about 4uAh in standby mode. A coin bat like CR2032 offer 200mAh. You can save your memory more than one year ... If you want a shorter time (days) but many cycles, you can use a supercap. What is the target application of your logger ? [1] http://www.microchip.com/wwwproducts/Devices.aspx?product=23LC1024

Lucky 11 years ago

EEPROM isn't such a bad idea in my opinion. It's true that the number of erase/write cycle is limited, but for many applications it will do. After all, modern EEPROMs are guaranteed for more than 1 million cycles.

BMWTouring 11 years ago

Oke. I thought the idea of EEPROM is that the data will be still there if I would have some kind of power loss. But I will look into SRAM. The help I request is first in the sense of: Getting the GPS NMEA stream onto my MMC. But the Stream is 5Hz. That's why I want to write the NMEA strings first to some sort of memory and at a different timing I will flush this to MMC. Is this a good design idea?