Brads Electronic Projects Forum

hey guys
i've just completed this as my school pic programming project
i had heaps of fun doing it

ill upload a video of my completed project on youtube here...



I used my schools laser cutter to make and raster the box.

That is the best looking housing I have seen! Very nice work indeed

You said it was for a school pic programming project - does this mean that everyone in your class made something aswell? I would have loved to have gone to a school where we got to work with microcontrollers!

i was the only one to make this, the rest of the class made a 'ruldoph' pic kit thing using a simple Pic microcontroller (model?) with 8 pins. We were taught how to do simple programming.
Definitely my best project yet.

brad wrote:That is the best looking housing I have seen! Very nice work indeed

You said it was for a school pic programming project - does this mean that everyone in your class made something aswell? I would have loved to have gone to a school where we got to work with microcontrollers!

Hi Brad,
On my project i just made, the red dot that moves is only red if you disconnect the green vertical column. I noticed on your pictures of 'the great race' you have a fully red dot (not orange) along with that row of green. All i did to get rid of the orange to make it red was disconnect pin 10 on the led display.

Can you possibly edit you 'the great race.asm' on you great race page that fixes this...It would be very much appreciated, but it doesn't matter if you cant.
Thanks heaps , great project.

bman2309 wrote:Hi Brad,
On my project i just made, the red dot that moves is only red if you disconnect the green vertical column. I noticed on your pictures of 'the great race' you have a fully red dot (not orange) along with that row of green. All i did to get rid of the orange to make it red was disconnect pin 10 on the led display.

Can you possibly edit you 'the great race.asm' on you great race page that fixes this...It would be very much appreciated, but it doesn't matter if you cant.
Thanks heaps , great project.

Hi bman2309, Im not sure that Brads .asm code needs fixing as Brads track actually goes into the last row with the RED dot car. Correct me if im wrong but if the red dot car turns Orange then this indicates that the car as crashed?. But are you saying bman2309 that your Red dot car was always Orange untill your disconnected pin 10?

yes the dot is always orange, even after i crash (which it then goes to score)

Let me double check the code and get back to you. But it should be just fine. have you checked your hardware?

is there any other sort of ghosting? I.E. pixels lighting up when they shouldnt?

Usually no, but one time i was playing it there was a green dot that mirrored the red dot on the other side. But i just turned it on then off and it stopped.

bman2309 wrote:Usually no, but one time i was playing it there was a green dot that mirrored the red dot on the other side. But i just turned it on then off and it stopped.

I would double check your hardware, could be a slight bit of solder touching somewhere else on the board or even a little bit of the copper track on the board, espically where you have made a cut to split the circuit into two?.

Hmm, I have checked the code and it all looks good. Unfortunately there's something not quite right with your circuit.

Just as bitfogav said, double check everything to make sure you don't have shorts where there shouldn't be shorts

Hey bman2309,

That's a great looking cover you made. Now wrap some surface mount LED's around the edges of the top plate and those Mario images will light up like crazy!

See here:
viewtopic.php?f=17&t=292

Stacy

I didn't think of that, it would look cool!

brad wrote:Hmm, I have checked the code and it all looks good. Unfortunately there's something not quite right with your circuit.

Just as bitfogav said, double check everything to make sure you don't have shorts where there shouldn't be shorts

I haven't built the 16F648A+7442 Great Race project but I did wonder if there is an error or oversight in the schematic (which might explain those symptoms). With the 7442 "D" input (pin 12) wired to ground, one of the green rows on the 7442 "0" through "7" outputs will ALWAYS be enabled, yes? If that's the case, then when you set RA3 low in the software to enable the red row, one of the green rows is still enabled, and that means whenever you light a red dot you'll also light a green dot. Now I haven't seen this phantom green + red dot in any of the Great Race videos I've come across so far, so I was wondering if my analysis is incorrect?

If my circuit and software analysis is correct however, then couldn't you eliminate the problem by using all four of the input address lines on the 7442 to fully decode and enable only "1 of 9" outputs for all nine rows (8 green rows + 1 red row)? That is, why not drive the 7442 "D" input from the RA3 line and use the 7442 "8" output line to drive the red row? Perhaps something like the circuit below?

Cheerful regards, Mike

You will get ghosting if you don't first ensure that you are sending all 1's out to cathodes of the Green LED's. If you do this then there is no way that any of the green LED's can light up because you have 5v connected to all of the Cathodes

brad wrote:You will get ghosting if you don't first ensure that you are sending all 1's out to cathodes of the Green LED's. If you do this then there is no way that any of the green LED's can light up because you have 5v connected to all of the Cathodes

Hi Brad,

I agree with you 100%. Unfortunately, I don't see any way you can set all of the green cathodes to 5v on your schematic. With pin 12 grounded on the 7442 in your circuit (the A3 input in the table below), there are only eight possible combinations of outputs and one of those outputs (all connected to green cathode rows) will always be low.