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Forum Index : Electronics : Another Picaxe Datalogger Started
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SparWeb Senior Member  Joined: 17/04/2008 Location: CanadaPosts: 196 |
Hi I thought this would pique some interest: 
All I've done so far is assemble the pieces of the PICAXE datalogger kit board, EEPROM, and LCD. Next I have to make it "wind enabled", meaning, give it sensors relevant to the windmill performance: wind speed, mill RPM, voltage, and battery charge current. The kit can be automatically programmed to get it started. I need to add some internal math to turn the raw numbers into calibrated values and make the LCD label the numbers in a more relevant way. Once the memory is full, the program normally stops, but I'd like it to keep feeding the LCD data. A few things to tweak like that. I'm a little disappointed that it can only accept 4 inputs - you'd think a DATA logger kit would be designed around something with more INput. The EEPROM memory keeps data stored (even when the power is off) until I can come along with a laptop and download the data. How much data depends on how often I make it write to the EEPROM and how many pieces of data go in each time. This is what's driving the whole change from Gizmo's excellent PICLOG design. Perhaps it is possible to make the 08M write to an EEPROM. I'm not the person to figure something like that out. 
The LCD outputs real time data, and I may want to mount it away from the datalogger box itself - maybe make it visible on the outside of the battery cabinet, for example. Oh lots of ideas, but it's past my bedtime and I'm just so pleased that I finally got it working, after days of fiddling, that I just had to post before crashing in bed.  Steven T. Fahey |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I've been thinking about adding some eeprom to the PicLog. Gills logger has inspired me. http://www.thebackshed.com/Windmill/articles/GillsDataLogger .asp It may be easier to start again from scratch, using a 18X chip with the extra imputs. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Gizmo, I have a picAXE28X2. recently released. 13 analogue inputs. My next toy to fiddle with. Gordon. become more energy aware |
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| SparWeb Senior Member Joined: 17/04/2008 Location: CanadaPosts: 196 |
The Picaxe 08M doesn't have enough memory for the program that runs the EEPROM and LCD. Maybe the Rev-Ed programming wizard's program could be trimmed a fair bit, but the profit is small when the 08M picaxe does work well. I've now got this setup relaying continuous telemetry to the data cable, the LCD, and storing it all in the EEPROM, once every 2 seconds. Steven T. Fahey |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Steven, How many readings can the EEPROM store? become more energy aware |
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| SparWeb Senior Member Joined: 17/04/2008 Location: CanadaPosts: 196 |
Quite a few. The 24L256 EEPROM chips can store 32kb each. With the AXE111 EEPROM board, there are 7 slots for these, in addition to the one built into the AXE datalogger board. I may not be using it to its full potential, because each of my data readings are single bytes, and the registers are addressed as 2-byte "words". That means I only use half of each register: 8 chips x 16384 registers = 131,072 readings By taking a reading every 2 seconds, it takes 4.5 hours to fill up. If each register held a 2-byte variable, I could increase that to 262,144 readings (9 hours). The datasheet says that 8 of these chips can hold up to 2MB, so I must be missing something! http://www.rev-ed.co.uk/docs/axe110_i2c.pdf At the moment, I'm using the EEPROM to record four inputs and the corresponding time from the clock (h:m:s). That takes up 7 bytes, so I have one left over for a fifth input. I only have to figure out HOW to get that input, because the datalogger board uses up all of the 18X pins! I'll cross that bridge when I come to it. Steven T. Fahey |
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| SparWeb Senior Member Joined: 17/04/2008 Location: CanadaPosts: 196 |
... of course... [quote]The datasheet says that 8 of these chips can hold up to 2MB, so I must be missing something![/quote] 2Mb is "two mega bits", 2MB is "two mega bytes". Not the same things. Now the claim makes sense. So 256 kilobytes is about the upper limit, and with my programming ability I only know how to use 128 kilobytes so far. Using Gizmo's datalogger as a reference, which records a reading every 10 seconds, then I could log for nearly 2 days. Steven T. Fahey |
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