No I don't have the logger but I'm wondering where I should purchase one. I have read DeKay's post and have considered making a direction serial connection. I just find it hard to pay $125.00 for something that can be made for under $10. I almost wish someone would start selling just the cable because I think you would have a market for it.
No I don't have the logger but I'm wondering where I should purchase one. I have read DeKay's post and have considered making a direction serial connection. I just find it hard to pay $125.00 for something that can be made for under $10. I almost wish someone would start selling just the cable because I think you would have a market for it.
It's not just a simple cable. And I don't remember anybody saying that a copy/equivalent can be made for under $10.
No I don't have the logger but I'm wondering where I should purchase one. I have read DeKay's post and have considered making a direction serial connection. I just find it hard to pay $125.00 for something that can be made for under $10. I almost wish someone would start selling just the cable because I think you would have a market for it.
How are you planning on incorporating the data into your irrigation system? I use a home automation program called HomeSeer, and import the data into it from VWS to do similar control.
FWIW, I've made a simple RS-232 serial cable for the VP2 console for about $25 in parts. As Bushman points out, it doesn't include a logger, buy the app for which I built it doesn't use the logger data, at least not at this time.
I used an off-the-shelf 3.3 v logic level to RS-232 adapter and a 2mm dual row header from Digi-Key.
I'm glad you asked :) I currently use a product called EtherRain. Its and IP based irrigation controller that works very well. It's has a well documented API and the guy who invented it wrote the Homeseer driver. I've been playing with it for some time and I love it.
http://board.homeseer.com/showthread.php?t=136596
I want to use it to measure rain fall rates to determine when to water. Right now I just use a rain sensor but I want something more accurate. I can calculate how much water my lawn needs daily and then see how much rain it has received. I would eventually like to calculate evapotranspiration as this is a more accurate number. I think I'll need Solar Radiation Sensors to calculate this.
You can also use EtherRain in combination with their website lawncheck.com. It allows you to set schedules and it uses Yahoo weather to predict rain and check rain fall rates.
Because of your interest in irrigation control, you might want to check out my SLOweather.com website. There you will see 2 different indexes, the Watering Index, and the Irrigation Index.
I created the Irrigation Index before I learned about the Watering Index.
The Irrigation Index is the running total of the last 7 days of rainfall subtracted from the running total of the last 7 days evapotranspiration or ET, as measured and calculated by the SLOweather weather station.
That tells you how much water in inches to put out this week.
The Watering Index was created by a California DWR engineer and is the percentage of the last 7 days running ET/highest weekly average ET for your area * 100.
On SLOweather, I've enhanced the WI by subtracting out the last 7 days rain from the ET to give a better representation.
Bottom line, get the solar sensor and use ET. You won't be sorry.
I'm glad you asked :) I currently use a product called EtherRain. Its and IP based irrigation controller that works very well. It's has a well documented API and the guy who invented it wrote the Homeseer driver. I've been playing with it for some time and I love it.
http://board.homeseer.com/showthread.php?t=136596
I want to use it to measure rain fall rates to determine when to water. Right now I just use a rain sensor but I want something more accurate. I can calculate how much water my lawn needs daily and then see how much rain it has received. I would eventually like to calculate evapotranspiration as this is a more accurate number. I think I'll need Solar Radiation Sensors to calculate this.
You can also use EtherRain in combination with their website lawncheck.com. It allows you to set schedules and it uses Yahoo weather to predict rain and check rain fall rates.
Very Cool, I love this. What are you using to control your irrigation?
Do you need the UV sensor to calculate ET? Can you give me an example on how you would use the watering index % to determine how much to water your grass?
I also notice you are comparing 10 years worth of ET. Are those the numbers you have collected?
TO reiterate, the Davis logger is NOT a simple serial/USB cable. It contains logging circuitry to retain the data from the station. If you build your or Dekay's cable you WILL NOT get that memory and if it burps, you lose the current data and subsequent till it feels better.
Has anyone actually taken one of these apart? I have a feeling they are just a cable. Isn't it the counsel that is keeping the history in memory? I have a feeling the only components in the USB cable is a USB to serial converter. Once I get my serial cable I'll open it up and take a look.
On the datalogger circuit board,
U1 is an Atmel 45DB memory http://www.atmel.com/dyn/resources/prod_documents/doc3688.pdf (http://www.atmel.com/dyn/resources/prod_documents/doc3688.pdf),
U2 is a Maxim MAX3221E RS-232 Transceiver http://www.maxim-ic.com/datasheet/index.mvp/id/1781/t/do (http://www.maxim-ic.com/datasheet/index.mvp/id/1781/t/do)
U3 is probably a voltage regulator, it is unmarked. All the other components are passive resistors, capacitors, diodes and a connector.
If anyone wishes to pursue this further, I'll trade this one for a new datalogger. :lol:
A general question to folks with the logger: is there an indication somewhere on the console display if a logger is plugged in? Does the logger have to be plugged in when the console is powered up for it to be recognized, or can you plug it in anytime?
In particular, it is usually the case that - if the console is powered up - unplugging the logger and plugging it back in will cause logging to cease until there is a complete power reset.
"Powered" in the above seems to mean "power available" (that is, including the batteries).
The package is soic. The P/N looks like 450B011B but I couldn't match that with a part, so I settled on 45DB011B. The top line is Atmel 0321 which is date 2003, 21st week.
No one seems to have electronics skills.
I think the Davis datalogger is a value priced item. I'll build you one for $300.00.
And of course, just after posting, it occurred to me that PB4, PE2, PE3, or PC4 could also either be pulled down to ground or pulled up to Vcc. That should be checked for as well.
No I don't have the logger but I'm wondering where I should purchase one. I have read DeKay's post and have considered making a direction serial connection. I just find it hard to pay $125.00 for something that can be made for under $10. I almost wish someone would start selling just the cable because I think you would have a market for it.
PB4 is connected to the backlight. I don't have anything in my notes for PE2, PE3 or PC4.
As far as I could tell, the PROM status was checked by pulling PB0 low and then sending 0x57 out the SPI.
Dan,I agree the price is a bargain. Some assume that this is a simple cable with unique connectors. We've discovered that this does indeed contain the memory/data logging and communications interface circuitry for VP2 to computer. What irks some is that the datalogger/cabling/software bundle looks like an afterthought that should have been included inside the console.
Even if it could be manufactured for $10 (which is doubtful unless they are making them in extremely large quantities), Davis undoubtedly has tens of thousands of $$$ (likely more) in Engineering and development costs, product testing and certification etc. It's not cheap to develop and bring even the simplest of products to market, have them tested to relevant safety standards etc. Being a EE myself in product development, I think $125 is a bargain. You've already shelled out several hundred for your VP2, why not just spend a little more and be done with it? Unless of course you just enjoy tinkering and building things yourself which I can certainly understand.
NP
What irks some is that the datalogger/cabling/software bundle looks like an afterthought that should have been included inside the console.
I might have made an error when I pinned this out. Will have to check that next time.
Now this makes perfect sense, since PB0 is muxed as Slave Select on the processor and 0x57 is the command to read the status register on the memory chip. Perhaps all that is needed is to just hook up the memory chip's SPI and power pins to the expansion port, like so:
And I've asked this before, C2520: how did you figure out all of this stuff?
; -----------------------------------------------------------------------------------------
;
; LAMPS
;
+0000A619: E045 LDI R20,0x05 ;chars
+0000A61A: EB21 LDI R18,0xB1 ;
+0000A61B: E23D LDI R19,0x2D ;0x2DB1 (LAMPS)
+0000A61C: D2D5 RCALL PC+0x02D6 ;A8F2 - check if string match
+0000A61D: F441 BRNE PC+0x09 ;A626 - Branch if not equal
;
+0000A61E: D996 RCALL PC-0x0669 ;9FB5 - Send "OK" out USART
+0000A61F: D2B1 RCALL PC+0x02B2 ;A8D1 -Relative call subroutine
+0000A620: 2B01 OR R16,R17 Logical OR
+0000A621: F011 BREQ PC+0x03 ;A624 -Branch if equal
;
+0000A622: 9AC4 SBI PORTB,4 Set bit in I/O register
+0000A623: CA8D RJMP PC-0x0572 ;A0B1 - 0x78 => (0x0927), restore regs and return
;
+0000A624: 98C4 CBI PORTB,4 Clear bit in I/O register
+0000A625: CA8B RJMP PC-0x0574 ;A0B1 - 0x78 => (0x0927), restore regs and return
; -----------------------------------------------------------------------------------------
This is the section of code that checks for the LAMPS command and handles it if found.I'd love to know how Davis "made them stop".
I was just wondering how you figured this stuff out in general terms. And it looks like you've taken a disassembler to the entire ROM and figured out the inner workings??? Wow. Just wow. My hat is off to you, sir. =D>And I've asked this before, C2520: how did you figure out all of this stuff?
If you did, I either missed it, or it was while my workstation was down and I couldn't reply at the time. This is benign enough that I suppose it's not likely to cause any issues, backup what I said about PB4, and provide a hint.
What software tools did you use to do this, BTW?
I'd love to know how Davis "made them stop".
I'd love to know how Davis "made them stop".
All they have to do is be able to pay their attorneys more than you can pay yours.
No I don't have the logger but I'm wondering where I should purchase one. I have read DeKay's post and have considered making a direction serial connection. I just find it hard to pay $125.00 for something that can be made for under $10. I almost wish someone would start selling just the cable because I think you would have a market for it.
Dan,
Even if it could be manufactured for $10 (which is doubtful unless they are making them in extremely large quantities), Davis undoubtedly has tens of thousands of $$$ (likely more) in Engineering and development costs, product testing and certification etc. It's not cheap to develop and bring even the simplest of products to market, have them tested to relevant safety standards etc. Being a EE myself in product development, I think $125 is a bargain. You've already shelled out several hundred for your VP2, why not just spend a little more and be done with it? Unless of course you just enjoy tinkering and building things yourself which I can certainly understand.
NP
On the datalogger circuit board,
U1 is an Atmel 45DB memory http://www.atmel.com/dyn/resources/prod_documents/doc3688.pdf (http://www.atmel.com/dyn/resources/prod_documents/doc3688.pdf),
U2 is a Maxim MAX3221E RS-232 Transceiver http://www.maxim-ic.com/datasheet/index.mvp/id/1781/t/do (http://www.maxim-ic.com/datasheet/index.mvp/id/1781/t/do)
U3 is probably a voltage regulator, it is unmarked. All the other components are passive resistors, capacitors, diodes and a connector.
If anyone wishes to pursue this further, I'll trade this one for a new datalogger. :lol:
And to DanITman: Bushman is right. Unless you use a USB->Serial converter that converts to 0V -> 3.3V LVTTL levels rather than +/-10V (or whatever), you'll very likely fry your console. Read the link in the last paragraph to see why.
DeKay, thank you for the reminder on the 3.3v. I have your read your blog in great detail and I appreciate you posting that info. I plan on using a MAX3223 to communicate with the counsel. Do you see that being a problem? I have one similar to this:
http://cgi.ebay.com/RS232-Serial-Port-TTL-Converter-MAX3223-3-3V-DIY-/230604730798?pt=LH_DefaultDomain_0&hash=item35b11cf1ae
I'm glad everyone set me straight that the data logger is actually in the cable and not just a cable that accesses the memory on the device. The device must have some type of memory to display historical results on the screen as well as keep high and low temps.
DeKay, thank you for the reminder on the 3.3v. I have your read your blog in great detail and I appreciate you posting that info. I plan on using a MAX3223 to communicate with the counsel. Do you see that being a problem? I have one similar to this:
http://cgi.ebay.com/RS232-Serial-Port-TTL-Converter-MAX3223-3-3V-DIY-/230604730798?pt=LH_DefaultDomain_0&hash=item35b11cf1ae
What software tools did you use to do this, BTW?
The actual disassembly is pretty easy, just download a bin from Davis, convert it to hex and load into AVR.
From that point, I wrote a program to calculate the actual addresses of all the relative offsets and further anoint the AVR disassembly. Then spend a couple/few years trying to figure it out.
Atmel's AVR Studio? I thought I tried doing that once but couldn't get it to pull in raw hex without source. Didn't spend a lot of time on it though so I could easily have missed something. I'd never played with Atmel micros before.
And of course, just after posting, it occurred to me that PB4, PE2, PE3, or PC4 could also either be pulled down to ground or pulled up to Vcc. That should be checked for as well.
PB4 is connected to the backlight. I don't have anything in my notes for PE2, PE3 or PC4.
As far as I could tell, the PROM status was checked by pulling PB0 low and then sending 0x57 out the SPI.