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Forum Index : Microcontroller and PC projects : Brickwall for RTC on Micromite
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Use an external RTC based on the DS3231 or DS3232 extremely accurate RTC, and never have to worry about 1307 drift ever again. 
3231 Extremely Accurate RTC They are more expensive then the 1307's, but only by about $2.(and they also have a 32K EEPROM onboard too) I much prefer 3231's or 3232's for RTC's - they are so much more accurate over time, and for a couple of extra bucks.... Well, that is certainly true. Smoke makes things work. When the smoke gets out, it stops! |
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Geoffg Guru  Joined: 06/06/2011 Location: AustraliaPosts: 3196 |
Would many people have the patience to do this? The reason that I ask is that this particular PIC32 has the ability to tweak the clock speed up or down by a few percent. I was wondering if it was worth making this available as yet another option - so people could fine tune the clock for accuracy. The internal clock is affected by temperature so the tweaking would only be effective at a certain temperature. Geoff Geoff Graham - http://geoffg.net |
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BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
The DS3231 also has a tweaking register to allow you to adjust the accuracy and on board temperature compensation. It does not need an external crystal. I haven't looked but I suspect the code for the 8563 may work for that too. I bought one of these recently from DX which had a rechargeable lithium cell. It also has on board temperature measurement(although not great resolution). edit: I bought mine at DX.com but it is identical to the one you linked Grogster. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
How do the prices compare? I like that module, as it has EEPROM on it too for data storage - all for five bucks!(in NZ money) As I understand from the datasheet for the 3231/3232, the I2C address is fixed, just like the 1703, and it is the same address. Smoke makes things work. When the smoke gets out, it stops! |
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| BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
currently US@4.63 but that's DX.com for you. Often just a little more than your eBay best price. I notice that eBay say they don't include the battery when shipped. DX.com has no such problems. DX.com DS3231 RTC with EEPROM |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6101 |
Where possible, I set my maximites from the PC as required (once a day usually) and the PC's are set from the Internet. I will be using the uMite as standalone loggers and looking for low power drain so I will still go with the 8563 and it's interrupt. In the meantime SETTICK 10018, tensecssub is an easy way to get an adjustable 10 second interupt. Having an official timer tweak would be useful as long as we understand that it will drift around. Jim VK7JH MMedit MMBasic Help |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Yeah, lots of traders on ebay I note, say that things using batteries won't ship with the batteries. I fully expect this is related to 9/11 and anti-terrorism, where batteries are used to try to set of bombs on planes etc, so by simply making it illegal to send anything with a battery in it, you go a long way towards ruling that kind of thing out. My sister lives in Germany, and she got a new iPhone, but the supplier would not send it with the battery - she had to buy a battery at her local shop. Seems to be an almost standard thing now with battery powered bits of kit, if they have to hop onto a plane to get to you. Smoke makes things work. When the smoke gets out, it stops! |
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Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 761 |
Hey Grogster... I downloaded the data sheet, then I started remembering that I might have one of these laying around.. (pause while rummaging).. I do have one... (nice) I think I got it with some other stuff from DX... Anyway, it would make an awesome little unit for the uMite.. (as you know, by the Pix I seen).. Does the code you have place 6 lines of text on the screen.? Since I guess you have to shift out the characters to the columns as you go. I guess a fixed array of bytes... not sure.. Sweet..! I like it. I try to get it hooked up.. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
I have not written anything for these modules, nor do I have any, but I am going to get some.  I only wrote that I liked them, cos I do, not cos I have actually used them - perhaps I need to clarify that at this point! 
I do love the cost, and the fact that the 3231/3232 is a much more accurate RTC then the 1307 in the first place. That, and we also have 32K of EEPROM memory to play with, all on the same module. Hard to beat that price-vs-features. At Element 14, DS3232 SOIC chips are $20 EACH , just for the chip, to say nothing of a little board and extra EEPROM.... EDIT: I have purchased 10 of these modules. Will probably never need 10, but they are so cheap, and the exchange rate is so good at the moment, that I figured - what the hell! 
Get ready, MOBI - once I get a hold of these things, I will start playing around with I2C in earnest, especially as I have an RTC and EEPROM on the same module. But as I have not really done anything at all with I2C, I might be in deep water for a start!  Smoke makes things work. When the smoke gets out, it stops! |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 761 |
Sorry Sir... I was talking about the LCD Display you had in the PIX... I was wondering how you wrote the code to drive it and if it is text only... It is a Good size for the uMite...! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308 |
Not me! 
You need to ask jman about that one - he was the guy with the LCD. I agree though, they are ideal for the uM and so cheap, I just about bought some. jman should start a thread about using that LCD - I am sure it would appeal to many.(hint, hint) Smoke makes things work. When the smoke gets out, it stops! |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Don't worry, You'll cope - it is dead simple David M. |
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OA47 Guru Joined: 11/04/2012 Location: AustraliaPosts: 926 |
Jman, is this code missing : BCDTEMP = RTCBuff(0) BCDtoDec BCDTEMP prior to: sec$ = Str$(decimal) ??????? |
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jman Guru Joined: 12/06/2011 Location: New ZealandPosts: 711 |
@ Graeme Worse that that :) Below is the correct code ' I2C RTC based On DS1307 Secs,Mins,Hours,Day,Date,Month,Year,Control Dim RTCbuff(8) i2caddr = &h68 ' DS1307 I2C address I2C open 100,100 ' Enable I2C I2C write I2caddr, 0, 1, 0 I2C Read i2caddr, 0, 8, RTCbuff(0) I2C Close BCDTEMP = RTCBuff(0) BCDtoDec BCDTEMP sec$ = Str$(decimal) BCDTEMP = RTCBuff(1) BCDtoDec BCDTEMP min$ = Str$(decimal) BCDTEMP = RTCBuff(2) BCDtoDec BCDTEMP hours$ = Str$(decimal) BCDTEMP = RTCBuff(4) BCDtoDec BCDTEMP day$ = Str$(decimal) bcdtemp = rtcbuff(5) BCDtoDec BCDTEMP month$ = Str$(decimal) bcdtemp = rtcbuff(6) BCDtoDec BCDTEMP year$ = Str$(decimal + 2000 ) t$ = hours$+":"+min$+":"+sec$ D$ = day$+"/"+month$+"/"+year$ Time$ = T$ Date$ = D$ Print "Time has been set to ";Time$ Print"Date has been set to ";Date$ End 'Convert to Decimal Sub BCDtoDec (BCDTEMP) Decimal = Fix(BCDTemp / 16) * 10 Decimal = Decimal + (BCDTEMP And &hF) End Sub Regards Jman |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
How do you manually alter the time for daylight saving etc? Most RTC chips have alarm registers that can be altered. Keypad and LCD display? i2c? David M. |
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