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Forum Index : Microcontroller and PC projects : Mini Maximite chip runs hot

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ernie
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Joined: 18/03/2012
Location: Australia
Posts: 14

Posted: 11:02am 18 Mar 2012

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I just went down to Jaycar yesterday and picked up the mini Maximite kit. Fascinating little thing, I use to program Apple][ in BASIC, it takes me back! First thing I noticed was the PIC32 chip runs quite hot to touch even when just sitting there not running anything other than at the MMBASIC prompt. Running the Vcc off at 2.96volt power supply. Is there a way to get at one of the lower power modes that PIC32 supports via MMBASIC?

I also observed a slight slowdown in execution speed when I did the upgrade from MMBASIC version 2.7 to version 3.1.

A simple test loop I ran to toggle the I/O pins, went from about 1640ms under 2.7 to 1738ms on 3.1, so I though it worth a mention.

This is the code:

10 Timer=0
100 For i = 0 To 999
200 For x = 1 To 20: Pin(x)=1:Pin(x)=0:Next x
300 Next i
500 Print Timer "ms for " (i) " iterations"

djuqa

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Joined: 23/11/2011
Location: Australia
Posts: 447

Posted: 11:31am 18 Mar 2012

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Welcome to this forum and the exciting world of 32bit Basic microcomputers.
1/ 2.96v for the 3.3v VCC is a little so PIC32 will run hotter than normal, but PIC32 can still function at quite high temps.
2/The low power modes are not currently accessible via MMBasic.
Edited by djuqa 2012-03-19

VK4MU MicroController Units

BobD

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Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 05:50pm 18 Mar 2012

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ernie said
I also observed a slight slowdown in execution speed when I did the upgrade from MMBASIC version 2.7 to version 3.1.

A simple test loop I ran to toggle the I/O pins, went from about 1640ms under 2.7 to 1738ms on 3.1, so I though it worth a mention.

This is the code:

10 Timer=0
100 For i = 0 To 999
200 For x = 1 To 20: Pin(x)=1:Pin(x)=0:Next x
300 Next i
500 Print Timer "ms for " (i) " iterations"

a 6% decrease in speed but v3.1 gives you a lot more capability if you can manage to remove the line numbers from your programs. They are optional in V3.1 and you may even get back the decrease in speed without them.

Try this:

Timer=0
For i = 0 To 999
For x = 1 To 20: Pin(x)=1:Pin(x)=0:Next x
Next i
Print Timer "ms for " (i) " iterations"

ernie
Newbie

Joined: 18/03/2012
Location: Australia
Posts: 14

Posted: 12:15am 19 Mar 2012

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I tried without line numbers, exactly the same execution time as with line numbers, I expect as you say, that the introduction of more functionality in 3.1 has caused a small speed reduction.

I noticed it because I am interesting in receiving data from an RC 2.4Ghz receiver, manipulating the data, and controlling outrunner motors with Electronic Speed Controllers, that need short pulses between 1-2ms as often as 50 to 400Hz. I know that it can be done in C or assembler pretty easily, but I was curious how fast the I/O in MMBASIC was.

Edited by ernie 2012-03-20

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