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Forum Index : Microcontroller and PC projects : Altronics Colour Maximite - Mystery Cap

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Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 2953
Posted: 05:15am 11 Dec 2012
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  paceman said  As I understand it, the RTC clock is only read once, immediately on power-up and then MMBasic keeps time from that - but it does somehow know if the RTC isn't running on power-up because it comes up with the "Clock Not Set" message under the logo to remind you to issue a Time/Date command. I assume that subsequent to that, if a new Time/Date MMBasic command is issued then it would also be written to the RTC, not just MMBasic.

This is exactly correct.

When the firmware access the chip it can tell if it is there or not, then it can tell if it has been set with a valid time (there are registers in the chip that provide this information).

A program running in MMBasic cannot access this chip because the Colour Maximite uses a second I2C interface to access the chip. This interface was available because of the 100 pin PIC32 and is different from the I2C interface that you can access from within MMBasic.

It does sounds like the crystal is faulty in Nick's CMM. Fortunately they are cheap enough and you can buy them from Altronics or Jaycar.

Geoff
Geoff Graham - http://geoffg.net
 
CircuitGizmos

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Joined: 08/09/2011
Location: United States
Posts: 1416
Posted: 06:10am 11 Dec 2012
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  ajkw said   Bill,
Well that is interesting. I would have thought the CGCOLORMAXI has the RTC wired to the same pins as the CMM, I haven't been able to find a schematic of the CGCOLORMAXI to confirm.

Anthony.


The CGCOLORMAX1 has the 'system' RTC wired to the same pins that the Colour Maximite.

The firmware has access to this RTC. A program written in MMBasic does not - it has a different I2C port.
Micromites and Maximites! - Beginning Maximite
 
ajkw
Senior Member

Joined: 29/06/2011
Location: Australia
Posts: 290
Posted: 11:37am 11 Dec 2012
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So the last 5 posts confirm that the I2C commands cannot communicate directly with the RTC from Basic as I originally pointed out. Perhaps for curiosities sake Bill can point out how his does (You see I would actually like to be able to do this)

My original post to Nick was intended to be a heads up about the use of i2ctime.bas to try fix his problem and that I didn't think it would work.
 
Nick

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Joined: 09/06/2011
Location: Australia
Posts: 512
Posted: 06:18pm 14 Dec 2012
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I found the problem regarding my clock not working!!

Went to Jaycar and bought another crystal for the clock and replaced the one that came with the kit.

Clock now works. It was a dud crystal all along.

Nick
 
Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 2953
Posted: 11:41am 15 Dec 2012
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Good news. I will add that one to the FAQ.
Geoff Graham - http://geoffg.net
 
jebz

Regular Member

Joined: 13/06/2011
Location: Australia
Posts: 79
Posted: 08:37pm 26 Dec 2012
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I've found a potential smoke producing error.
The ISCP overlay on the Altronics board has the key on the wrong side resulting in the reversal of the pins. If a programmer is connected smoke may be released.

D2 is also missing from the circuit and D3 is drawn as a zener diode. A reason for this may be because D2 has been moved over close to IC2 on the Altronics PCB.

C10, this was a challenge. I'd pay $1 more for the IC machine to put it on the board when the PIC micro was attached. I assembled my Maximite V1 and soldered the PIC on successfully but the C10 capacitor on the colour Maximite is too small to hang onto.

My new colour Maximite is going, now I need to update the firmware.

My appreciation to Geoff and his skill in designing this compact computer.
 
crez

Senior Member

Joined: 24/10/2012
Location: Australia
Posts: 150
Posted: 03:15am 27 Dec 2012
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Just a note on what appears to be an error in the Altronics color maximite kit instructions. The diagram Fig 9 on page 11 shows the 5v on the bottom side of the 26 pin connector. It is actually on the top side. The 5v and 3.3v labels on Fig 9 should be swapped. I got caught with this when I was feeding 5v into inputs that should not go over 3.3v.

David
 
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